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Barocco RL, Clohessy JW, O'Brien GK, Dufault NS, Anco DJ, Small IM. Sensor-Based Quantification of Peanut Disease Defoliation Using an Unmanned Aircraft System and Multispectral Imagery. Plant Dis 2024; 108:416-425. [PMID: 37526489 DOI: 10.1094/pdis-05-23-0847-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/02/2023]
Abstract
Early leaf spot (Passalora arachidicola) and late leaf spot (Nothopassalora personata) are two of the most economically important foliar fungal diseases of peanut, often requiring seven to eight fungicide applications to protect against defoliation and yield loss. Rust (Puccinia arachidis) may also cause significant defoliation depending on season and location. Sensor technologies are increasingly being utilized to objectively monitor plant disease epidemics for research and supporting integrated management decisions. This study aimed to develop an algorithm to quantify peanut disease defoliation using multispectral imagery captured by an unmanned aircraft system. The algorithm combined the Green Normalized Difference Vegetation Index and the Modified Soil-Adjusted Vegetation Index and included calibration to site-specific peak canopy growth. Beta regression was used to train a model for percent net defoliation with observed visual estimations of the variety 'GA-06G' (0 to 95%) as the target and imagery as the predictor (train: pseudo-R2 = 0.71, test k-fold cross-validation: R2 = 0.84 and RMSE = 4.0%). The model performed well on new data from two field trials not included in model training that compared 25 (R2 = 0.79, RMSE = 3.7%) and seven (R2 = 0.87, RMSE = 9.4%) fungicide programs. This objective method of assessing mid-to-late season disease severity can be used to assist growers with harvest decisions and researchers with reproducible assessment of field experiments. This model will be integrated into future work with proximal ground sensors for pathogen identification and early season disease detection.[Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY 4.0 International license.
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Affiliation(s)
- Rebecca L Barocco
- North Florida Research and Education Center, Department of Plant Pathology, University of Florida Institute of Food and Agricultural Sciences, Quincy, FL 32351
| | - James W Clohessy
- North Florida Research and Education Center, Department of Plant Pathology, University of Florida Institute of Food and Agricultural Sciences, Quincy, FL 32351
| | - G Kelly O'Brien
- North Florida Research and Education Center, Department of Plant Pathology, University of Florida Institute of Food and Agricultural Sciences, Quincy, FL 32351
| | - Nicholas S Dufault
- Department of Plant Pathology, University of Florida Institute of Food and Agricultural Sciences, Gainesville, FL 32611
| | - Daniel J Anco
- Edisto Research and Education Center, Department of Plant and Environmental Sciences, Clemson University, Blackville, SC 29817
| | - Ian M Small
- North Florida Research and Education Center, Department of Plant Pathology, University of Florida Institute of Food and Agricultural Sciences, Quincy, FL 32351
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Barro JP, Del Ponte EM, Allen T, Bond JP, Faske TR, Hollier CA, Kandel YR, Mueller DS, Kelly HM, Kleczewski NM, Ames KA, Price P, Sikora EJ, Bradley CA. Meta-Analytic Modeling of the Severity-Yield Relationships in Soybean Frogeye Leaf Spot Epidemics. Plant Dis 2023; 107:3422-3429. [PMID: 37093164 DOI: 10.1094/pdis-03-23-0440-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Frogeye leaf spot (FLS), caused by Cercospora sojina, is an important foliar disease affecting soybean in the United States. A meta-analytic approach including 39 fungicide trials conducted from 2012 to 2021 across eight states (Alabama, Arkansas, Illinois, Iowa, Kentucky, Louisiana, Mississippi, Tennessee) was used to assess the relationship between FLS severity and soybean yield. Correlation and regression analyses were performed separately to determine Fisher's transformation of correlation coefficients (Zr), intercept (β0) and slope (β1). Disease pressure (low severity, ≤34.5; high severity, >34.5%) and yield class (low, ≤3,352; high, >3,352 kg/ha) were included as categorical moderators. Pearson's [Formula: see text], obtained from back-transforming the [Formula: see text]r estimated by an overall random-effects model, showed a significant negative linear relationship between FLS severity and yield ([Formula: see text] = -0.60). The [Formula: see text]r was affected by disease pressure (P = 0.0003) but not by yield class (P = 0.8141). A random-coefficient model estimated a slope of -19 kg/ha for each percent severity for a mean attainable yield of 3,719.9 kg/ha. Based on the overall mean (95% CI) of the intercept and slope estimated by the random-coefficients model, the estimated overall relative damage coefficient was 0.51% (0.36 to 0.69), indicating that a percent increase in FLS severity reduced yield by 0.51%. The best model included yield class as a covariate, and population-average intercepts differed significantly between low (3,455.1 kg/ha) and high (3,842.7 kg/ha) yield classes. This highlights the potential impact of FLS on soybean yield if not managed and may help in disease management decisions.
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Affiliation(s)
- Jhonatan P Barro
- Department of Plant Pathology, University of Kentucky, Princeton, KY 42445, U.S.A
- Departamento de Fitopatologia, Universidade Federal de Viçosa, 36570-000, Viçosa, Brazil
| | - Emerson M Del Ponte
- Departamento de Fitopatologia, Universidade Federal de Viçosa, 36570-000, Viçosa, Brazil
| | - Tom Allen
- Delta Research and Extension Center, Mississippi State University, Stoneville, MS 38776, U.S.A
| | - Jason P Bond
- Department of Plant, Soil Science and Agricultural Systems, Southern Illinois University, Carbondale, IL 62901, U.S.A
| | - Travis R Faske
- Department of Entomology and Plant Pathology, University of Arkansas, Division of Agriculture, Lonoke Extension Center, Lonoke, AR 72086, U.S.A
| | - Clayton A Hollier
- Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, LA 70803, U.S.A
| | - Yuba R Kandel
- Department of Plant Pathology, Entomology and Microbiology, Iowa State University, Ames, IA 50011, U.S.A
| | - Daren S Mueller
- Department of Plant Pathology, Entomology and Microbiology, Iowa State University, Ames, IA 50011, U.S.A
| | - Heather M Kelly
- Department of Entomology and Plant Pathology, University of Tennessee, Jackson, TN 38301, U.S.A
| | - Nathan M Kleczewski
- Department of Crop Sciences, University of Illinois, Urbana, IL 61801, U.S.A
| | - Keith A Ames
- Department of Crop Sciences, University of Illinois, Urbana, IL 61801, U.S.A
| | - Paul Price
- Macon Ridge Research Station, LSU AgCenter, Winnsboro, LA 71295, U.S.A
| | - Edward J Sikora
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849, U.S.A
| | - Carl A Bradley
- Department of Plant Pathology, University of Kentucky, Princeton, KY 42445, U.S.A
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Poti T, Thitla T, Imaiam N, Arunothayanan H, Doungsa-Ard C, Kongtragoul P, Nalumpang S, Akimitsu K. Isolates of Colletotrichum truncatum with Resistance to Multiple Fungicides from Soybean in Northern Thailand. Plant Dis 2023; 107:2736-2750. [PMID: 36691275 DOI: 10.1094/pdis-08-22-1882-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
In Thailand, four systemic fungicides-carbendazim (Car), azoxystrobin (Azo), difenoconazole (Dif), and penthiopyrad (Pen)-are commonly used to control soybean anthracnose caused by Colletotrichum truncatum; however, the pathogen has developed resistance. From 2019 to 2020, fungicide resistance in C. truncatum from fields in Chiang Rai and Chiang Mai was monitored. In tests of 85 C. truncatum isolates for resistance to multiple fungicides, 15.3% were CarRAzoR, 34.1% were triple resistant (CarRAzoRDifR or CarRAzoRPenR), and 50.6% were CarRAzoRDifRPenR. Surprisingly, all isolates tested had lost their sensitivity to one or more of the fungicides tested. The carbendazim-resistant isolates carried a point mutation in the β-tubulin gene at codon 198 (E198A) or 200 (F200Y), and all azoxystrobin-resistant isolates had a mutation in the cytochrome b gene at codon 143 (G143A) or 129 (F129L). Moreover, a novel mutation at codon 208 (S208Y) in the gene encoding succinate dehydrogenase subunit B was detected in all of the isolates highly resistant to penthiopyrad. No mutation linked with difenoconazole resistance was detected in the genes encoding cytochrome P450 sterol 14α-demethylase. To the best of our knowledge, this is the first report of C. truncatum isolates resistant to multiple fungicides and serves as a warning to take measures to prevent the occurrence and distribution of these multiple-fungicide-resistant populations in soybean fields.
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Affiliation(s)
- Teeranai Poti
- Faculty of Agriculture, Kagawa University, Kagawa 761-0795, Japan
- The United Graduated School of Agricultural Sciences, Ehime University, Ehime 790-8577, Japan
| | - Tanapol Thitla
- Department of Entomology and Plant Pathology, Faculty of Agriculture, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Naphatsawan Imaiam
- Department of Entomology and Plant Pathology, Faculty of Agriculture, Chiang Mai University, Chiang Mai 50200, Thailand
| | | | - Chanintorn Doungsa-Ard
- Department of Agriculture, Plant Pathology Research Group, Plant Protection Research and Development Office, Bangkok 10900, Thailand
| | - Pornprapa Kongtragoul
- Department of Agricultural Technology, King Mongkut's Institute of Technology Ladkrabang, Prince of Chumphon Campus, Chumphon 86160, Thailand
| | - Sarunya Nalumpang
- Department of Entomology and Plant Pathology, Faculty of Agriculture, Chiang Mai University, Chiang Mai 50200, Thailand
| | - Kazuya Akimitsu
- Faculty of Agriculture, Kagawa University, Kagawa 761-0795, Japan
- The United Graduated School of Agricultural Sciences, Ehime University, Ehime 790-8577, Japan
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Cerritos-Garcia DG, Huang SY, Kleczewski NM, Mideros SX. Virulence, Aggressiveness, and Fungicide Sensitivity of Phytophthora spp. Associated with Soybean in Illinois. Plant Dis 2023:PDIS07221551RE. [PMID: 36415892 DOI: 10.1094/pdis-07-22-1551-re] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Phytophthora root and stem rot (PRR), caused by Phytophthora sojae, is one of the most devastating oomycete diseases of soybean in Illinois. Single resistant genes (Rps) are used to manage this pathogen but P. sojae has adapted to Rps, causing failure of resistance in many regions. In addition to P. sojae, recent reports indicate that P. sansomeana could also cause root rot in soybean. Soil samples and symptomatic plants were collected across 40 Illinois counties between 2016 and 2018. P. sojae (77%) was more abundant than P. sansomeana (23%) across Illinois fields. Both species were characterized by virulence, aggressiveness, and fungicide sensitivity. Virulence of all P. sojae isolates was evaluated using the hypocotyl inoculation technique in 13 soybean differentials. Aggressiveness was evaluated in the greenhouse by inoculating a susceptible cultivar and measuring root and shoot dry weight. On average, P. sojae isolates were able to cause disease on six soybean differentials. P. sojae was more aggressive than P. sansomeana. All isolates were sensitive to azoxystrobin, ethaboxam, mefenoxam, and metalaxyl. The characterization of the population of species associated with PRR will inform management decisions for this disease in Illinois.
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Affiliation(s)
| | - Shun-Yuan Huang
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Nathan M Kleczewski
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Santiago X Mideros
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801
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Deng Y, Li JC, Lyv X, Xu JW, Wu MD, Zhang J, Yang L, Li GQ. Large-Scale Surveys of Blackleg of Oilseed Rape ( Leptosphaeria biglobosa) Revealed New Insights into Epidemics of This Disease in China. Plant Dis 2023:PDIS08221765RE. [PMID: 36222724 DOI: 10.1094/pdis-08-22-1765-re] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Blackleg of oilseed rape caused by Leptosphaeria maculans/L. biglobosa is a worldwide important disease. L. maculans is more virulent than L. biglobosa, so it causes a great concern for oilseed rape production. In China, blackleg (L. biglobosa) of oilseed rape was reported in the 2000s, but epidemiological features of blackleg have not been well elucidated. Moreover, whether L. maculans exists in China is still an open question. Therefore, a 5-year survey was done in China to collect blackleg-occurrence data for characterizing the features of blackleg epidemics and to identify the blackleg pathogens for assessing the risk of L. maculans invasion. The results showed that all the 19 surveyed provinces had blackleg on oilseed rape, and the most frequently occurring provinces are Gansu, Qinghai, Shaanxi, and Hubei. Phoma stem canker was the most common symptom, which was associated with stem cracks on winter oilseed rape and with stem-weevil activities on spring oilseed rape. Temperature and rainfall were the main factors for blackleg epidemics on winter oilseed rape, whereas rainfall was the main factor for blackleg epidemics on spring oilseed rape. Brassica campestris and B. juncea oilseed rapes were more susceptible than B. napus to blackleg. Oilseed rapes cultivated under the continuous dry land-cropping pattern were more prone to blackleg than those cultivated under the paddy land/dry land-cropping pattern. All 6,015 fungal isolates from blackleg plant tissues belonged to L. biglobosa. These results are helpful for understanding the blackleg epidemics of oilseed rapes and for management of this disease in China.
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Affiliation(s)
- Y Deng
- State Key Laboratory of Agricultural Microbiology and Hubei Key Laboratory of Plant Pathology, Huazhong Agricultural University, Wuhan 430070, China
| | - J C Li
- State Key Laboratory of Agricultural Microbiology and Hubei Key Laboratory of Plant Pathology, Huazhong Agricultural University, Wuhan 430070, China
| | - X Lyv
- State Key Laboratory of Agricultural Microbiology and Hubei Key Laboratory of Plant Pathology, Huazhong Agricultural University, Wuhan 430070, China
| | - J W Xu
- Plant Protection Station of Chibi City of Hubei Province, Chibi 437300, China
| | - M D Wu
- State Key Laboratory of Agricultural Microbiology and Hubei Key Laboratory of Plant Pathology, Huazhong Agricultural University, Wuhan 430070, China
| | - J Zhang
- State Key Laboratory of Agricultural Microbiology and Hubei Key Laboratory of Plant Pathology, Huazhong Agricultural University, Wuhan 430070, China
| | - L Yang
- State Key Laboratory of Agricultural Microbiology and Hubei Key Laboratory of Plant Pathology, Huazhong Agricultural University, Wuhan 430070, China
| | - G Q Li
- State Key Laboratory of Agricultural Microbiology and Hubei Key Laboratory of Plant Pathology, Huazhong Agricultural University, Wuhan 430070, China
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6
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Heineck GC, Casanova J, Porter LD. Suitable Methods of Inoculation and Quantification of Fusarium Root Rot in Lentil. Plant Dis 2023:PDIS07221658RE. [PMID: 36265151 DOI: 10.1094/pdis-07-22-1658-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Lentil (Lens culinaris L. subsp. culinaris) is an important grain legume grown worldwide. As its popularity grows among consumers and more acres are produced, new root rot complexes have become more prevalent. This work sought to develop methods for studying root rot caused by Fusarium avenaceum in lentil using controlled environments. The objectives were to (i) find an effective and seed-safe sterilization technique, (ii) optimize the inoculation technique and lentil growing environment, and (iii) develop visual and automated disease scoring systems. Results showed the use of detergent and a low concentration (0.1%) of NaClO (the active ingredient in bleach) maintained germinability and effectively eliminated bacterial and fungal contamination on seeds. Other treatments, such as ethanol, reduced seed germination or failed to kill pathogenic fungi such as Fusarium spp. Placing inoculum at a moderate rate of 1 × 106 spores both directly on the seed and on top of the media covering the seed improved severity scores and reduced escapes compared with placement on top of the media only. Visual severity scoring systems and diagrammatic scales were developed for scoring the cotyledon region and roots. A computer vision algorithm was designed to improve the efficiency of scoring the cotyledon region and roots for disease severity using a simple RGB camera and lightbox. Visual and computer scores were best correlated when images were visually scored on a monitor, and multiple images were averaged. The scores generated from the computer vision algorithm had better correlations with visual scores for cotyledon rot (r = 0.92 and β1 = 0.96) than root rot (r = 0.62 and β1 = 0.67).
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Affiliation(s)
- G C Heineck
- USDA-ARS Northwest Sustainable Agroecosystems Research Unit, Washington State University, Prosser, WA 99350
| | - Joaquin Casanova
- USDA-ARS Northwest Sustainable Agroecosystems Research Unit, Washington State University, Pullman, WA 99164
| | - Lyndon D Porter
- USDA-ARS Grain Legume Genetics and Physiology Research Unit, Prosser, WA 99350
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Kandel YR, Lawson MN, Brown MT, Chilvers MI, Kleczewski NM, Telenko DEP, Tenuta AU, Smith DL, Mueller DS. Field and Greenhouse Assessment of Seed Treatment Fungicides for Management of Sudden Death Syndrome and Yield Response of Soybean. Plant Dis 2023; 107:1131-1138. [PMID: 36190301 DOI: 10.1094/pdis-03-22-0527-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Seed treatments for the management of sudden death syndrome (SDS) caused by Fusarium virguliforme are available in the United States and Canada; however, side-by-side comparisons of these seed treatments are lacking. Sixteen field experiments were established in Illinois, Indiana, Iowa, Michigan, and Wisconsin, United States, and Ontario, Canada, in 2019 and 2020 to evaluate seed treatment combinations. Treatments included a nontreated check (NTC), fungicide and insecticide base seed treatments (base), fluopyram, base + fluopyram, base + saponin extracts from Chenopodium quinoa, base + fluopyram + heat-killed Burkholderia rinojenses, base + pydiflumetofen, base + thiabendazole + heat-killed B. rinojenses, and base + thiabendazole + C. quinoa extracts + heat-killed B. rinojenses. Treatments were tested on SDS moderately resistant and susceptible soybean cultivars at each location. Overall, NTC and base had the most root rot, most foliar disease index (FDX), and lowest yield. Base + fluopyram and base + pydiflumetofen were most effective for managing SDS. Moderately resistant cultivars reduced FDX in both years but visual root rot was greater on the moderately resistant than the susceptible cultivars in 2020. Yield response to cultivar was also inconsistent between the 2 years. In 2020, the susceptible cultivar provided significantly more yield than the moderately resistant cultivar. Treatment effect for root rot and FDX was similar in field and greenhouse evaluations. These results reinforce the need to include root rot evaluations in addition to foliar disease evaluations in the breeding process for resistance to F. virguliforme and highlights the importance of an integrated SDS management plan because not a single management tactic alone provides adequate control of the disease.
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Affiliation(s)
- Yuba R Kandel
- Department of Plant Pathology, Entomology and Microbiology, Iowa State University, Ames, IA 50011, U.S.A
| | - Maia N Lawson
- Department of Plant Pathology, Entomology and Microbiology, Iowa State University, Ames, IA 50011, U.S.A
| | - Mariama T Brown
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907, U.S.A
| | - Martin I Chilvers
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
| | - Nathan M Kleczewski
- Department of Crop Sciences, University of Illinois, Urbana, IL 61801, U.S.A
| | - Darcy E P Telenko
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907, U.S.A
| | - Albert U Tenuta
- Ontario Ministry of Agriculture, Food, and Rural Affairs, Ridgetown, Ontario N0P2C0, Canada
| | - Damon L Smith
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706, U.S.A
| | - Daren S Mueller
- Department of Plant Pathology, Entomology and Microbiology, Iowa State University, Ames, IA 50011, U.S.A
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8
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Harveson RM, Al Rwahnih M, Tian T, Karasev A, Gulya TJ, Bradshaw JD. The Quest to Identify a New Virus Disease of Sunflower from Nebraska. Plant Dis 2022; 106:2773-2783. [PMID: 36191166 DOI: 10.1094/pdis-11-21-2402-fe] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Between 2010 and 2018, sunflower plants exhibiting virus-like symptoms, including stunting, mottling, and chlorotic ringspots on leaves, were observed from commercial fields and research plots from four sites within three distinct counties of western Nebraska (Box Butte, Kimball, and Scotts Bluff). Near identical symptoms from field samples were reproduced on seedlings mechanically in the greenhouse on multiple occasions, confirming the presence of a sap-transmissible virus from each site. Symptomatic greenhouse-inoculated plants from the 2010 and 2011 Box Butte samples tested negative for sunflower mosaic virus (SuMV), sunflower chlorotic mottle virus (SuCMoV), and all potyviruses in general by ELISA and RT-PCR. Similar viral-like symptoms were later observed on plants in a commercial sunflower field in Kimball County in 2014, and again from volunteers in research plots in Scotts Bluff County in 2018. Samples from both of these years were again successfully reproduced on seedlings in the greenhouse as before following mechanical transmissions. Symptom expression for all years began 12 to 14 days after inoculation as mild yellow spots followed by the formation of chlorotic ringspots from the mottled pattern. The culture from 2014 tested negatively for three groups of nepoviruses via RT-PCR, ruling this group out. However, transmission electron microscopy assays of greenhouse-infected plants from both 2014 and 2018 revealed the presence of distinct, polyhedral virus particles. With the use of high throughput sequencing and RT-PCR, it was confirmed that the infections from both years were caused by a new virus in the tombusvirus genus and was proposed to be called Sunflower ring spot mottle virus (SuRSMV). Although the major objective of this project was to identify the causal agent of the disease, it became evident that the diagnostic journey itself, with all the barriers encountered on the 10-year trek, was actually more important and impactful than identification.
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Affiliation(s)
- R M Harveson
- University of Nebraska, Panhandle REC, Scottsbluff, NE
| | | | - T Tian
- California Department of Food and Agriculture, Sacramento, CA
| | | | - T J Gulya
- USDA-ARS, Northern Crop Science Laboratory, Fargo, ND (retired)
| | - J D Bradshaw
- University of Nebraska, Panhandle REC, Scottsbluff, NE
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9
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Raza MM, Kaiser MS, Eggenberger SK, Nutter FW, Leandro LFS. Time of Soybean Sudden Death Syndrome Foliar Symptom Onset Influences Final Disease Intensity, Yield, and Yield Components. Plant Dis 2022; 106:2392-2402. [PMID: 35196103 DOI: 10.1094/pdis-07-21-1551-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Sudden death syndrome (SDS), caused by Fusarium virguliforme, causes substantial yield losses in soybean. However, relationships between soybean yield and components of disease progress, including time of disease onset, are poorly understood. Individual soybean plants (2018) and quadrats (2016 to 2018) were monitored in commercial fields and experimental plots in Iowa to quantify the impact of SDS foliar symptom onset on final SDS intensity, soybean yield components, and yield. The date when SDS foliar symptoms were first detected (onset time) and progress of SDS incidence and severity were recorded weekly. Individual soybean plants and quadrats were harvested at the end of each season. Beta-regression showed that date of SDS onset had a consistent and stable effect on final disease intensity both at individual plant and quadrat levels. The slope of the relationship between date of SDS onset and final SDS severity was common across all field sites and years. Weighted linear regression revealed that SDS onset explained 60 to 83% of the variation in number of pods, number of seeds, and total seed weight in individual plants, and 94 to 97% of the variation in seed yield in quadrats. Soybean yield damage functions (slopes) indicated that for each day SDS onset was delayed, soybean yield increased by 30.5 to 31.3 kg/ha. This new quantitative information improves understanding of the impact of SDS on final disease intensity and soybean yield. Further experiments are needed to determine how this relationship is affected by site-specific factors.
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Affiliation(s)
- Muhammad M Raza
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA 50011
| | - Mark S Kaiser
- Department of Statistics, Iowa State University, Ames, IA 50011
| | - Sharon K Eggenberger
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA 50011
| | - Forest W Nutter
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA 50011
| | - Leonor F S Leandro
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA 50011
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10
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Farias OR, Cruz JMFL, Veloso JS, Duarte IG, Barbosa PRR, Félix MRF, Varanda CMR, Materatski P, Oliveira MDM, Nascimento LC. Occurrence of Fusarium proliferatum Causing Vascular Wilt on Cowpea ( Vigna unguiculata) in Brazil. Plant Dis 2022; 106:PDIS04210839PDN. [PMID: 35226821 DOI: 10.1094/pdis-04-21-0839-pdn] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Affiliation(s)
- O R Farias
- Programa de Pós-Graduação em Agronomia, Universidade Federal da Paraíba, PB 079, 58.397-000, Areia, Brazil
| | - J M F L Cruz
- Programa de Pós-Graduação em Agronomia, Universidade Federal da Paraíba, PB 079, 58.397-000, Areia, Brazil
| | - J S Veloso
- Programa de Pós-Graduação em Fitopatologia, Universidade Federal Rural de Pernambuco, Departamento de Agronomia, Dois Irmãos, 52.171-900, Recife, Brazil
| | - I G Duarte
- Programa de Pós-Graduação em Fitopatologia, Universidade Federal Rural de Pernambuco, Departamento de Agronomia, Dois Irmãos, 52.171-900, Recife, Brazil
| | - P R R Barbosa
- Instituto de Ciências Agrárias, Universidade Federal dos Vales do Jequitinhonha e Mucuri - Campus Unaí, 38.610-000, Unaí, Brazil
| | - M R F Félix
- Mediterranean Institute for Agriculture, Environment and Development, Universidade de Évora, Polo da Mitra, 7006-554, Évora, Portugal
| | - C M R Varanda
- Mediterranean Institute for Agriculture, Environment and Development, Universidade de Évora, Polo da Mitra, 7006-554, Évora, Portugal
| | - P Materatski
- Mediterranean Institute for Agriculture, Environment and Development, Universidade de Évora, Polo da Mitra, 7006-554, Évora, Portugal
| | - M D M Oliveira
- Programa de Pós-Graduação em Agronomia, Universidade Federal da Paraíba, PB 079, 58.397-000, Areia, Brazil
| | - L C Nascimento
- Programa de Pós-Graduação em Agronomia, Universidade Federal da Paraíba, PB 079, 58.397-000, Areia, Brazil
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11
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Ajithkumar K, Savitha AS, Mahadevakumar S, Maharachchikumbura SSN, Sreenivasa MY, Rathnakumar AL, Sujatha M. First Report of Molecular Detection of Leveillula taurica Associated with Powdery Mildew of Linseed ( Linum usitatissimum) from India. Plant Dis 2022; 106:1529. [PMID: 34713727 DOI: 10.1094/pdis-09-21-1937-pdn] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Affiliation(s)
- K Ajithkumar
- AICRP on Linseed, Main Agricultural Research Station, University of Agricultural Sciences, Raichur - 584 104, Karnataka, India
| | - A S Savitha
- Department of Plant Pathology, College of Agriculture, University of Agricultural Sciences, Raichur - 584 104, Karnataka, India
| | - S Mahadevakumar
- Applied Phytopathology Laboratory, Department of Studies in Botany, University of Mysore, Manasagangotri, Mysuru - 570 006, Karnataka, India
| | - S S N Maharachchikumbura
- School of Life Sciences and Technology, Center for Informational Biology, University of Electronic Science and Technology of China, Chengdu 611731, P.R. China
| | - M Y Sreenivasa
- Phytopathology Laboratory, Department of Studies in Microbiology, University of Mysore, Manasagangotri, Mysuru - 570 006, Mysuru, Karnataka, India
| | - A L Rathnakumar
- Indian Institute of Oil Seed Research, Rajendranagar, Hyderabad, India
| | - M Sujatha
- Indian Institute of Oil Seed Research, Rajendranagar, Hyderabad, India
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12
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Webster RW, Roth MG, Mueller BD, Mueller DS, Chilvers MI, Willbur JF, Mourtzinis S, Conley SP, Smith DL. Integration of Row Spacing, Seeding Rates, and Fungicide Applications for Control of Sclerotinia Stem Rot in Glycine max. Plant Dis 2022; 106:1183-1191. [PMID: 34813712 DOI: 10.1094/pdis-09-21-1931-re] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Soybean (Glycine max) farmers in the Upper Midwest region of the United States often experience severe yield losses due to Sclerotinia stem rot (SSR). Previous studies have revealed benefits of individual management practices for SSR. This study examined the integration of multiple control practices on the development of SSR, yield, and the economic implications of these practices. Combinations of row spacings, seeding rates, and fungicide applications were examined in multisite field trials across the Upper Midwest from 2017 to 2019. These trials revealed that wide row spacing and low seeding rates individually reduced SSR levels but also reduced yields. Yields were similar across the three highest seeding rates examined. However, site-years where SSR developed showed the highest partial profits at the intermediate seeding rates. This finding indicates that partial profits in diseased fields were reduced by high seeding rates, but this trend was not observed when SSR did not develop. Fungicides strongly reduced the development of SSR while also increasing yields. However, there was a reduction in partial profits due to their use at a low soybean sale price, but at higher sale prices fungicide use was similar to not treating. Additionally, the production of new inoculum was predicted from disease incidence, serving as an indicator of increased risk for SSR development in future years. Overall, this study suggests using wide rows and low seeding rates in fields with a history of SSR while reserving narrow rows and higher seeding rates for fields without a history of SSR.
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Affiliation(s)
- Richard W Webster
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706
| | - Mitchell G Roth
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706
- Department of Plant Pathology, The Ohio State University, Wooster, OH 44691
| | - Brian D Mueller
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706
| | - Daren S Mueller
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA 50011
| | - Martin I Chilvers
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824
| | - Jaime F Willbur
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824
| | | | - Shawn P Conley
- Department of Agronomy, University of Wisconsin-Madison, Madison, WI 53706
| | - Damon L Smith
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, WI 53706
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13
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Beck-Okins AL, Del Río Mendoza LE, Burrows M, Simons KJ, Pasche JS. Pea seed-borne mosaic virus (PSbMV) Risk Analysis of Field Pea Based on Susceptibility, Yield Loss, and Seed Transmission. Plant Dis 2022; 106:938-946. [PMID: 34410862 DOI: 10.1094/pdis-06-21-1349-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Pea seed-borne mosaic virus (PSbMV), a nonpersistently aphid-transmitted potyvirus, has been reported in field pea (Pisum sativum L.)-growing regions worldwide. In 2014, PSbMV was first identified in field peas in North Dakota, U.S.A. Susceptibility and yield losses attributed to PSbMV infection are influenced by viral pathotype and host genotype. Isolate ND14-1, recovered from North Dakota infected seed and identified as pathotype 4 (P4), was mechanically inoculated onto 20 field pea cultivars under greenhouse conditions. PSbMV susceptibility, number of seeds and pods per plant, yield, symptom expression, and PSbMV seed transmission rates were assessed by cultivar. A risk assessment was developed based on cultivar susceptibility, yield reduction, and PSbMV seed transmission. Risk factors were weighted based on perceived importance to commercial field pea producers. Three cultivars were classified as low risk, seven cultivars were classified as intermediate risk, and 10 cultivars were classified as high risk. Two of the low-risk cultivars, Aragorn and Cruiser, were confirmed to be resistant to this isolate of PSbMV. Cultivar Arcadia was susceptible to PSbMV infection with mild expression of symptoms, but was classified as low risk based on a low seed transmission rate and diminished yield losses. This risk assessment could prove a useful tool for growers in field pea cultivar selection where PSbMV is prevalent.
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Affiliation(s)
| | | | - Mary Burrows
- Department of Plant Sciences and Plant Pathology, Montana State University, Bozeman, MT 59717
| | - Kristin J Simons
- Department of Plant Sciences, North Dakota State University, Fargo, ND 58108
| | - Julie S Pasche
- Department of Plant Pathology, North Dakota State University, Fargo, ND 58108
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14
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Abstract
Identifying the pathotype structure of a Phytophthora sojae population is crucial for the effective management of Phytophthora stem and root rot of soybean (PRR). P. sojae has been successfully managed with major resistance genes, partial resistance, and fungicide seed treatments. However, prolonged use of resistance genes or fungicides can cause pathogen populations to adapt over time, rendering resistance genes or fungicides ineffective. A statewide survey was conducted to characterize this pathotype structure and fungicide sensitivity of P. sojae within Michigan. Soil samples were collected from 69 fields with a history of PRR and fields having consistent plant stand establishment issues. Eighty-three isolates of P. sojae were obtained, and hypocotyl inoculations were performed on 14 differential soybean cultivars, all of which carry a single Rps gene or no resistance gene. The survey identified a loss of effectiveness of Rps genes 1b, 1k, 3b, and 6, compared with a previous survey conducted in Michigan from 1993 to 1997. Three effective resistance genes were identified for P. sojae management in Michigan; Rps 3a, 3c, and 4. Additionally, the effective concentration of common seed treatment fungicides to inhibit mycelial growth by 50% (EC50) was determined. No P. sojae isolates were insensitive to the tested chemistries with mean EC50 values of 2.60 × 10-2 μg/ml for ethaboxam, 3.03 × 10-2 μg/ml for mefenoxam, 2.88 × 10-4 μg/ml for oxathiapiprolin, and 5.08 × 10-2 μg/ml for pyraclostrobin. Results suggest that while there has been a significant shift in Rps gene effectiveness, seed treatments are still effective for early season management of this disease.
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Affiliation(s)
- Austin G McCoy
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824
| | - Zachary A Noel
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824
- Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849
| | - Janette L Jacobs
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824
| | - Kayla M Clouse
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS 66045
| | - Martin I Chilvers
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824
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15
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Abstract
Peanut (Arachis hypogaea L.) is cultivated in tropical and subtropical regions of the world as an important source of oil and protein. Until now, bacterial wilt, caused by Ralstonia solanacearum, was the only known bacterial disease of peanut. In 2020, widespread incidence of poor stand establishment was observed in multiple production fields planted to the Spanish-type peanut varieties in the Texas Panhandle. The observed symptoms included seed rot, pre- and postemergence damping-off, poor seedling vigor, poorly developed root systems with little or no nodule formation, and death. Subsequent diagnosis of symptomatic seedlings recovered two bacterial species identified by BLAST using 676- and 661-bp 16S rRNA fragments as a Ralstonia sp. and a Pantoea sp., respectively. To investigate a possible causative role of these bacteria in the observed peanut disease, the pathogenicity of the two isolates was evaluated under greenhouse conditions relying on Koch's postulates. Cell suspensions of the two bacteria, separately and in combination, were used to inoculate seeds of a Valencia-type peanut variety with no history of the disease and found to be pathogenic on the resultant seedling plants. Symptoms that developed on the inoculated plants were similar to the symptoms initially observed in the field, including seed rot, pre- and postemergence damping-off, poor seedling vigor, and root establishment. The two bacteria were also successfully recovered from inoculated and symptomatic plants, thus satisfying Koch's postulates. Given the early onset of symptom development on affected seeds and seedlings, a seedborne origin of the disease, described here as early-decline bacterial disease of peanut, was investigated in the same batches of peanut seeds that were planted, as well as seeds later harvested in some of the affected fields. Identical bacterial species, on the basis of 16S rRNA identity, were recovered from all of the seeds evaluated indicating that the bacteria are both seedborne and seed-transmissible. Multilocus sequence analysis involving six genes (dnaK, fumC, gyrB, murG, trpB, and tuf) showed that these new strains are most closely related to R. pickettii and Pantoea dispersa, but also phylogenetically distinct. The two bacteria were designated Ralstonia sp. strain B265 and Pantoea sp. strain B270. Losses from the disease in affected fields in 2020 averaged 50% (US$1.12 million) from a total of nine production fields. Findings from this study provide evidence for two new bacterial pathogens of peanuts capable of infecting Spanish and Valencia peanut varieties.
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Affiliation(s)
- Ken Obasa
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843
| | - Leonard Haynes
- Texas A&M AgriLife Extension Services, Texas A&M University System, College Station, TX 77843
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16
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Murithi HM, Pawlowski M, Degu T, Hunde D, Malede M, Obua T, Mushoriwa H, Coyne D, Tukamuhabwa P, Hartman GL. Evaluation of Soybean Entries in the Pan-African Trials for Response to Coniothyrium glycines, the Cause of Red Leaf Blotch. Plant Dis 2022; 106:535-540. [PMID: 34645304 DOI: 10.1094/pdis-05-21-1017-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Red leaf blotch (RLB), caused by the fungus Coniothyrium glycines, is an important disease of soybean known to cause yield losses across soybean-growing regions in Africa. Fungicides are one option to manage this disease, but utilization of host resistance may be a better option suited for smallholder soybean farmers in Africa. Fifty-nine soybean entries were evaluated for RLB severity in nine field locations in Ethiopia, Kenya, Uganda, and Zambia. Disease incidence was 100% and disease severity differed (P < 0.01) among entries at eight of the nine locations. Mean severity ratings ranged from 1.4 to 3.2 based on a 0-to-5 scale, with higher disease severities recorded in Ethiopia followed by Zambia. Eight of the 59 entries were common to all nine locations and had severity ratings ranging from 1.6 to 2.9. The cultivar SC Signal had the lowest RLB severity ratings in the combined analysis over locations. Based on correlations of weather variables to RLB severity, mean rainfall from planting to 30 days before assessment date had a positive correlation (r = 0.70; P = 0.035), as did mean morning maximum wind speed (r = 0.88; P = 0.016). Other variables, such as temperature and relative humidity, did not correlate to RLB severity. This is the most comprehensive report to date on the occurrence of RLB in the region, which for the first time demonstrates an association between rainfall and wind speed with RLB severity. It also represents the first extensive report evaluating soybean genotypes for resistance against RLB in multiple environments.
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Affiliation(s)
- Harun M Murithi
- Agricultural Research Service Research Participation Program through the Oak Ridge Institute for Science and Education, Oak Ridge, TN 37830, U.S.A
- International Institute of Tropical Agriculture, Nairobi, Kenya 00100
| | - Michelle Pawlowski
- U.S. Agency for International Development, Feed the Future Innovation Lab for Soybean Value Chain Research, Urbana, IL 61801, U.S.A
| | - Tizazu Degu
- Pawe Agricultural Research Center, Pawe, Ethiopia
| | | | - Molla Malede
- Pawe Agricultural Research Center, Pawe, Ethiopia
| | - Tonny Obua
- School of Agricultural Sciences, College of Agricultural and Environmental Sciences, Makerere University, Kampala, Uganda
| | - Hapson Mushoriwa
- International Crops Research Institute for the Semi-Arid Tropics, Harare, Zimbabwe
| | - Danny Coyne
- International Institute of Tropical Agriculture, Nairobi, Kenya 00100
| | - Phinehas Tukamuhabwa
- School of Agricultural Sciences, College of Agricultural and Environmental Sciences, Makerere University, Kampala, Uganda
| | - Glen L Hartman
- U.S. Department of Agriculture Agricultural Research Service and Department of Crop Sciences, University of Illinois, Urbana, IL 61801, U.S.A
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17
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Rehman A, Alam MW, Saira M, Naz S, Mushtaq R, Chohan TA, Din SU, Noureen A, Gilani K, Hussain D. Nigrospora sphaerica Causing Leaf Blight Disease on Sesame in Pakistan. Plant Dis 2022; 106:317. [PMID: 34340558 DOI: 10.1094/pdis-03-21-0460-pdn] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Affiliation(s)
- A Rehman
- Department of Plant Pathology, University of Agriculture, Faisalabad 38040, Pakistan
| | - M W Alam
- Department of Plant Pathology, University of Agriculture, Faisalabad 38040, Pakistan
- Department of Plant Pathology, University of Okara, Pakistan
| | - M Saira
- Plant Pathology Research Institute, Ayub Agricultural Research Institute Faisalabad, 38000, Punjab, Pakistan
| | - S Naz
- Plant Pathology Research Institute, Ayub Agricultural Research Institute Faisalabad, 38000, Punjab, Pakistan
| | - R Mushtaq
- Institute of Molecular Biology and Biotechnology, The University of Lahore, Pakistan
| | - T A Chohan
- Institute of Molecular Biology and Biotechnology, The University of Lahore, Pakistan
| | - S U Din
- Institute of Molecular Biology and Biotechnology, The University of Lahore, Pakistan
| | - A Noureen
- Institute of Molecular Biology and Biotechnology, The University of Lahore, Pakistan
| | - K Gilani
- Institute of Molecular Biology and Biotechnology, The University of Lahore, Pakistan
| | - D Hussain
- Institute of Molecular Biology and Biotechnology, The University of Lahore, Pakistan
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18
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Sun F, Sun S, Ye W, Duan C, Li B, Shan W, Zhu Z. Genome Sequence Data of Three Formae Speciales of Phytophthora vignae Causing Phytophthora Stem Rot on Different Vigna Species. Plant Dis 2021; 105:3732-3735. [PMID: 34003033 DOI: 10.1094/pdis-11-20-2546-a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Phytophthora vignae is an important oomycete pathogen causing Phytophthora stem rot on some Vigna spp. Three P. vignae isolates obtained from mung bean, adzuki bean, and cowpea exhibited high similarities in morphology and physiology but are specialized to infect different hosts. Here, we report the first de novo assembly of the draft genomes of three P. vignae isolates, which were performed using the PacBio SMRT Sequel platform. This study will extend the genomic resource available for the Phytophthora genus and provide a good foundation for further research on comparative genomics of Phytophthora spp. and interaction mechanism between hosts and pathogens.
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Affiliation(s)
- Feifei Sun
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, P. R. China
- College of Agronomy of Northwest Agriculture & Forestry University, Yangling, 712100, P. R. China
| | - Suli Sun
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, P. R. China
| | - Wenwu Ye
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, 210095, P. R. China
| | - Canxing Duan
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, P. R. China
| | - Benjin Li
- Institute of Plant Protection, Fujian Academy of Agricultural Sciences, Fuzhou, 350003, P. R. China
| | - Weixing Shan
- College of Agronomy of Northwest Agriculture & Forestry University, Yangling, 712100, P. R. China
| | - Zhendong Zhu
- Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing, 100081, P. R. China
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19
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Xing M, Guan G, Zhang X, Sun H, Wang Z, Pang W, Piao Z, Yang X, Feng J, Liang Y. Spatiotemporal Quantification of Plasmodiophora brassicae Inoculum in Relation to Clubroot Development Under Inoculated and Naturally Infested Field Conditions. Plant Dis 2021; 105:3636-3642. [PMID: 34018813 DOI: 10.1094/pdis-03-21-0653-re] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Clubroot caused by Plasmodiophora brassicae is a destructive disease of cruciferous plants worldwide. A quantitative PCR (qPCR) system specific to P. brassicae was developed. Analysis of the qPCR sensitivity indicated that the lower limit of detection was 1 × 101 resting spores/ml, 1 × 102 spores/g of soil, and 1 × 103 spores/g of roots and seeds. The regression curves generated from the qPCR data of different samples had a parallel relationship. The difference between the theoretical and actual concentrations was lowest at 1 × 105 spores/g of sample, compared with other concentrations. The P. brassicae biomass in soil and plant root tissues after inoculated with different spore concentrations was correlated. A correlation analysis confirmed that the clubroot incidence and disease index at 6 weeks after inoculation increased as the spore concentration increased. Under field conditions, the natural inoculum density of the P. brassicae population decreased at the early stage and then increased, with P. brassicae mainly being detected at a soil depth of 0 to 50 cm. The horizontal distribution of P. brassicae varied in the field with occurrences of hot spots. This study established a qPCR-based method for quantitative detection of clubroot. The developed assay is useful for monitoring the spatiotemporal dynamics of P. brassicae in the field. It may also be applicable for clubroot forecasting as a part of proactive disease management.
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Affiliation(s)
- Manzhu Xing
- College of Plant Protection, Shenyang Agricultural University, Shenyang 110866, China
- Liaoning Key Laboratory of Plant Pathology, Shenyang Agricultural University, Shenyang 110866, China
| | - Gege Guan
- College of Plant Protection, Shenyang Agricultural University, Shenyang 110866, China
- Liaoning Key Laboratory of Plant Pathology, Shenyang Agricultural University, Shenyang 110866, China
| | - Xinyu Zhang
- College of Plant Protection, Shenyang Agricultural University, Shenyang 110866, China
- Liaoning Key Laboratory of Plant Pathology, Shenyang Agricultural University, Shenyang 110866, China
| | - Huiying Sun
- College of Plant Protection, Shenyang Agricultural University, Shenyang 110866, China
- Liaoning Key Laboratory of Plant Pathology, Shenyang Agricultural University, Shenyang 110866, China
| | - Zehao Wang
- College of Plant Protection, Shenyang Agricultural University, Shenyang 110866, China
- Liaoning Key Laboratory of Plant Pathology, Shenyang Agricultural University, Shenyang 110866, China
| | - Wenxing Pang
- College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
| | - Zhongyun Piao
- College of Horticulture, Shenyang Agricultural University, Shenyang 110866, China
| | - Xinyu Yang
- College of Plant Protection, Shenyang Agricultural University, Shenyang 110866, China
- Liaoning Key Laboratory of Plant Pathology, Shenyang Agricultural University, Shenyang 110866, China
| | - Jie Feng
- Alberta Plant Health Lab, Alberta Agriculture and Forestry, Edmonton, Alberta T5Y6H3, Canada
| | - Yue Liang
- College of Plant Protection, Shenyang Agricultural University, Shenyang 110866, China
- Liaoning Key Laboratory of Plant Pathology, Shenyang Agricultural University, Shenyang 110866, China
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20
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Abstract
Sclerotinia sclerotiorum is a notorious fungal pathogen that causes sclerotinia stem rot (SSR) on many important crops in China and worldwide. Here, we present a high-quality genome assembly of S. sclerotiorum strain WH6 using the PacBio SMRT cell platform. The assembled genome has a total size of 38.96 Mbp, with a contig N50 length of 1.90 Mbp, and encodes 10,512 predicted coding genes, including 685 secreted proteins and 65 effector candidates. This is the first report of a S. sclerotiorum genome sequence from China. The WH6 genome sequence provides a valuable resource for facilitating our understanding of S. sclerotiorum-host interactions and SSR control in China and the world.
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Affiliation(s)
- Xiong Zhang
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture of the PRC, Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Wuhan 430062, China
| | - Xiaohui Cheng
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture of the PRC, Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Wuhan 430062, China
| | - Lijiang Liu
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture of the PRC, Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Wuhan 430062, China
| | - Shengyi Liu
- Key Laboratory of Biology and Genetic Improvement of Oil Crops, Ministry of Agriculture of the PRC, Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Wuhan 430062, China
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21
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Meinhardt C, Howland A, Ellersieck M, Scaboo A, Diers B, Mitchum MG. Resistance Gene Pyramiding and Rotation to Combat Widespread Soybean Cyst Nematode Virulence. Plant Dis 2021; 105:3238-3243. [PMID: 33449807 DOI: 10.1094/pdis-12-20-2556-re] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Soybean cyst nematode (SCN) is an important pathogen of soybean causing >$1 billion in yield losses annually in the United States. Planting SCN-resistant soybean cultivars is the primary management strategy. Resistance genes derived from the plant introduction (PI) 88788 (rhg1-b) and PI 548402 (Peking; rhg1-a and Rhg4) are the main types of resistance available in commercial cultivars. The PI 88788 rhg1-b resistance allele is found in the majority of SCN-resistant cultivars in the north central United States. The widespread use of PI 88788 rhg1-b has led to limited options for farmers to rotate resistance sources to manage SCN. Consequently, overreliance on a single type of resistance has resulted in the selection of SCN populations that have adapted to reproduce on these resistant cultivars. Here we evaluated the effectiveness of rotating soybean lines with different combinations of resistance genes to determine the best strategy for combating the widespread increase in virulent SCN and limit future nematode adaptation to resistant cultivars. Eight SCN populations were developed by continuous selection of a virulent SCN field population (Heterodera glycines [HG] type 1.2.5.7) on a single resistance source or in rotation with soybean pyramiding different resistance gene alleles derived from PI 88788 (rhg1-b), PI 437654 (rhg1-a and Rhg4), PI 468916 (cqSCN-006 and cqSCN-007), and PI 567516C (Chr10). SCN population densities were determined for eight generations. HG type tests were conducted after the eighth generation to evaluate population shifts. The continued use of rhg1-b or 006/007 had limited effectiveness for reducing SCN type 1.2.5.7 population density, whereas rotation to the use of rhg1-a/Rhg4 resistance significantly reduced SCN population density but selected for broader SCN virulence (HG type 1.2.3.5.6.7). A rotation of rhg1-a/Rhg4 with a pyramid of rhg1-b/006/007/Chr10 was the most effective combination at both reducing population density and minimizing selection pressure. Our results provide guidance for implementation of a strategic SCN resistance rotation plan to manage the widespread virulence on PI 88788 and sustain the future durability of SCN resistance genes.
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Affiliation(s)
- Clinton Meinhardt
- Division of Plant Sciences and Bond Life Sciences Center, University of Missouri, Columbia, MO 65211
| | - Amanda Howland
- Division of Plant Sciences and Bond Life Sciences Center, University of Missouri, Columbia, MO 65211
| | - Mark Ellersieck
- Agriculture Experiment Station Statistician, University of Missouri, Columbia, MO 65211
| | - Andrew Scaboo
- Division of Plant Sciences, University of Missouri, Columbia, MO 65211
| | - Brian Diers
- Department of Crop Sciences, University of Illinois, Urbana, IL 61801
| | - Melissa G Mitchum
- Division of Plant Sciences and Bond Life Sciences Center, University of Missouri, Columbia, MO 65211
- Department of Plant Pathology and Institute of Plant Breeding, Genetics, and Genomics, University of Georgia, Athens, GA 30602
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22
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Du R, Huang Y, Zhang J, Yang L, Wu M, Li GQ. LAMP Detection and Identification of the Blackleg Pathogen Leptosphaeria biglobosa 'brassicae'. Plant Dis 2021; 105:3192-3200. [PMID: 33560882 DOI: 10.1094/pdis-08-20-1819-re] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Blackleg of oilseed rape is a damaging invasive disease caused by the species complex Leptosphaeria maculans (Lm)/L. biglobosa (Lb), which is composed of at least two and seven phylogenetic subclades, respectively. Generally, Lm is more virulent than Lb, but under certain conditions, Lb can cause a significant yield loss in oilseed rape. Lb 'brassicae' (Lbb) has been found to be the causal agent for blackleg of oilseed rape in China, whereas Lm and Lb 'canadensis' (Lbc) were frequently detected in imported seeds of oilseed rape, posing a risk of spread into China. To monitor the blackleg-pathogen populations, a diagnostic tool based on loop-mediated isothermal amplification (LAMP) was developed using a 615-bp-long DNA sequence from Lbb that was derived from a randomly amplified polymorphic DNA assay. The LAMP was optimized for temperature and time, and tested for specificity and sensitivity using the DNA extracted from Lbb, Lbc, Lm, and 10 other fungi. The results showed that the optimal temperature and time were 65°C and 40 min, respectively. The LAMP primer set was specific to Lbb and highly sensitive as it detected the Lbb DNA as low as 132 fg per reaction. The LAMP assay was validated using the DNA extracted from mycelia and conidia of a well-characterized Lbb isolate, and its utility was evaluated using the DNA extracted from leaves, stems, pods, and seeds of oilseed rape. The LAMP assay developed herein will help for monitoring populations of the blackleg pathogens in China and in developing strategies for management of the blackleg disease.
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Affiliation(s)
- Ran Du
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
| | - Yongju Huang
- School of Life and Medical Sciences, University of Hertfordshire, Hatfield, AL10 9AB UK
| | - Jing Zhang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
| | - Long Yang
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
| | - Mingde Wu
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
| | - Guo-Qing Li
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, China
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23
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Petrović K, Skaltsas D, Castlebury LA, Kontz B, Allen TW, Chilvers MI, Gregory N, Kelly HM, Koehler AM, Kleczewski NM, Mueller DS, Price PP, Smith DL, Mathew FM. Diaporthe Seed Decay of Soybean [ Glycine max (L.) Merr.] Is Endemic in the United States, But New Fungi Are Involved. Plant Dis 2021; 105:1621-1629. [PMID: 33231523 DOI: 10.1094/pdis-03-20-0604-re] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Diaporthe seed decay can compromise seed quality in soybean [Glycine max (L.) Merr.] in the warm and humid production areas of the United States during crop maturation. In the current study, 45 isolates of Diaporthe were recovered from seed sampled from soybean fields affected by Diaporthe-associated diseases in eight U.S. states in 2017. The isolates obtained belonged to 10 species of Diaporthe based on morphology and phylogenetic analyses of the internal transcribed spacer, partial translation elongation factor 1-α, and β-tubulin gene sequences. The associated species included D. aspalathi, D. caulivora, D. kongii, D. longicolla, D. sojae, D. ueckerae, D. unshiuensis, and three novel fungi, D. bacilloides, D. flavescens, and D. insulistroma. One isolate each of the 10 species was examined for pathogenicity on seed of cultivar Sava under controlled conditions. Seven days postinoculation, significant differences in the percentages of decayed seeds and seedling necrosis were observed among the isolates and the noninoculated control (P < 0.0001). While the isolates of D. bacilloides, D. longicolla, and D. ueckerae caused a significantly greater percentage of decayed seeds (P < 0.0001), the isolate of D. aspalathi caused the greatest seedling necrosis (P < 0.0001). The observation of new fungi causing Diaporthe seed decay suggests the need for a more comprehensive survey in U.S. soybean producing areas since members of the genus Diaporthe appear to form a complex that causes seed decay.
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Affiliation(s)
- Kristina Petrović
- Department of Agronomy, Horticulture, and Plant Science, South Dakota State University, Brookings, SD 57007, U.S.A
- Department of Soybean, Institute of Field and Vegetable Crops, Novi Sad 21000, Serbia
| | - Demetra Skaltsas
- Mycology and Nematology Genetic Diversity and Biology Laboratory, U.S. Department of Agriculture Agricultural Research Service, Beltsville, MD 20705, U.S.A
| | - Lisa A Castlebury
- Mycology and Nematology Genetic Diversity and Biology Laboratory, U.S. Department of Agriculture Agricultural Research Service, Beltsville, MD 20705, U.S.A
| | - Brian Kontz
- Department of Agronomy, Horticulture, and Plant Science, South Dakota State University, Brookings, SD 57007, U.S.A
| | - Tom W Allen
- Delta Research and Extension Center, Mississippi State University, Stoneville, MS 38776, U.S.A
| | - Martin I Chilvers
- Department of Plant, Soil, and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
| | - Nancy Gregory
- Department of Plant and Soil Sciences, University of Delaware, Newark, DE 19716, U.S.A
| | - Heather M Kelly
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, TN 37996, U.S.A
| | - Alyssa M Koehler
- Department of Plant and Soil Sciences, University of Delaware, Georgetown, DE 19947, U.S.A
| | - Nathan M Kleczewski
- Department of Crop Sciences, University of Illinois, Urbana-Champaign, IL 61820, U.S.A
| | - Daren S Mueller
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA 50011, U.S.A
| | - Paul P Price
- Department of Plant Pathology and Crop Physiology, Louisiana State University AgCenter, Winnsboro, LA 71295, U.S.A
| | - Damon L Smith
- Department of Plant Pathology, University of Wisconsin, Madison, WI 53706, U.S.A
| | - Febina M Mathew
- Department of Agronomy, Horticulture, and Plant Science, South Dakota State University, Brookings, SD 57007, U.S.A
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24
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Abstract
Cabbage, a widely used and popular vegetable, and oilseed rape, the second most valuable oilseed crop in the world, are two important species from the Brassicaceae family. Two geographically separated outbreaks of cabbage and oilseed rape root rot with estimated incidence of 15 and 20%, respectively, were recorded during 2017 in the Vojvodina region, Serbia. Twelve hyphal-tip isolates were obtained from symptomatic cabbage and oilseed rape plants and identified as Waitea circinata var. zeae based on morphological and molecular features. This indicates that W. circinata var. zeae has expanded its host range to the Brassicaceae family. Sequence analyses of internal transcribed spacer (ITS) and large subunit of the ribosomal DNA, RPB2, and β-tubulin genes revealed the highest similarity with multiple W. circinata var. zeae. Neighbor-joining analyses of ITS sequences resulted in a phylogenetic tree with one well-defined branch of W. circinata var. zeae, with two separate groups. All Serbian isolates and the majority of isolates originating from natural infection of dicotyledonous plants grouped together in group I. Following artificial inoculation, W. circinata var. zeae isolates caused mild to medium root necrosis of seedlings of 2 monocotyledonous and 12 dicotyledonous plant species, implying a wider host range than was known for W. circinata var. zeae. Additionally, this is the first occurrence of W. circinata var. zeae on dicotyledonous host plants in Europe. Because cabbage and oilseed rape are important crops grown worldwide, the occurrence of this new soilborne pathogen with a broad host range imposes the necessity for changes in routine disease control practices, particularly crop rotation.
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Affiliation(s)
- Mira Vojvodić
- University of Belgrade, Faculty of Agriculture, Nemanjina 6, Belgrade, Serbia
| | - Brankica Tanović
- Institute of Pesticides and Environmental Protection, Banatska 31b, Belgrade, Serbia
| | - Petar Mitrović
- Institute of Field and Vegetable Crops, National Institute of the Republic of Serbia, Maksima Gorkog 30, Novi Sad, Serbia
| | - Ivana Vico
- University of Belgrade, Faculty of Agriculture, Nemanjina 6, Belgrade, Serbia
| | - Aleksandra Bulajić
- University of Belgrade, Faculty of Agriculture, Nemanjina 6, Belgrade, Serbia
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25
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Askarian H, Akhavan A, Manolii VP, Cao T, Hwang SF, Strelkov SE. Virulence Spectrum of Single-Spore and Field Isolates of Plasmodiophora brassicae Able to Overcome Resistance in Canola ( Brassica napus). Plant Dis 2021; 105:43-52. [PMID: 33107783 DOI: 10.1094/pdis-03-20-0471-re] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Clubroot, caused by Plasmodiophora brassicae Woronin, is an important disease of canola (Brassica napus L.) that is managed mainly by planting clubroot-resistant (CR) cultivars. Field isolates of P. brassicae can be heterogeneous mixtures of various pathotypes, making assessments of the genetics of host-pathogen interactions challenging. Thirty-four single-spore isolates were obtained from nine field isolates of the pathogen collected from CR canola cultivars. The virulence patterns of the single-spore and field isolates were assessed on the 13 host genotypes of the Canadian Clubroot Differential (CCD) set, which includes the differentials of Williams and Somé et al. Indices of disease (IDs) severity of 25, 33, and 50% (±95% confidence interval) were compared as potential thresholds to distinguish between resistant and susceptible reactions, with an ID of 50% giving the most consistent responses for pathotype classification purposes. With this threshold, 13 pathotypes could be distinguished based on the CCD system, 7 on the differentials of Williams, and 3 on the hosts of Somé et al. The highest correlations were observed among virulence matrices generated using the three threshold IDs on the CCD set. Genetically homogeneous single-spore isolates gave a clearer profile of the P. brassicae pathotype structure. Novel pathotypes, not reported in Canada previously, were identified among the isolates. This large collection of single-spore isolates can serve as a reference in screening and breeding for clubroot resistance.
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Affiliation(s)
- Homa Askarian
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada
| | - Alireza Akhavan
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada
| | - Victor P Manolii
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada
| | - Tiesen Cao
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada
| | - Sheau-Fang Hwang
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada
| | - Stephen E Strelkov
- Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, AB T6G 2P5, Canada
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26
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Gilley MA, Gulya TJ, Seiler GJ, Underwood W, Hulke BS, Misar CG, Markell SG. Determination of Virulence Phenotypes of Plasmopara halstedii in the United States. Plant Dis 2020; 104:2823-2831. [PMID: 32955406 DOI: 10.1094/pdis-10-19-2063-re] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Downy mildew, caused by Plasmopara halstedii (Farl.) Berl. and de Toni, is an economically important disease in cultivated sunflowers, Helianthus annuus L. Resistance genes incorporated into commercial hybrids are used as an effective disease management tool, but the duration of effectiveness is limited as virulence evolves in the pathogen population. A comprehensive assessment of pathogen virulence was conducted in 2014 and 2015 in the U.S. Great Plains states of North Dakota and South Dakota, where approximately 75% of the U.S. sunflower is produced annually. The virulence phenotypes (and races) of 185 isolates were determined using the U.S. standard set of nine differentials. Additionally, the virulence phenotypes of 61 to 185 isolates were determined on 13 additional lines that have been used to evaluate pathogen virulence in North America and/or internationally. Although widespread virulence was identified on several genes, new virulence was identified on the Pl8 resistance gene, and no virulence was observed on the PlArg, Pl15, Pl17 and Pl18 genes. Results of this study suggest that three additional lines should be used as differentials and agree with previous studies that six lines proposed as differentials should be used in two internationally accepted differential sets. For effective disease management using genetic resistance, it is critical that virulence data be relevant and timely. This is best accomplished when pathogen virulence is determined frequently and by using genetic lines containing resistance genes actively incorporated into commercial cultivars.
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Affiliation(s)
- Michelle A Gilley
- Department of Plant Pathology, North Dakota State University, Fargo, ND 58102
| | | | | | | | | | | | - Samuel G Markell
- Department of Plant Pathology, North Dakota State University, Fargo, ND 58102
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27
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Nachilima C, Chigeza G, Chibanda M, Mushoriwa H, Diers BD, Murithi HM, Hartman GL. Evaluation of Foliar Diseases for Soybean Entries in the Pan-African Trials in Malawi and Zambia. Plant Dis 2020; 104:2068-2073. [PMID: 32515688 DOI: 10.1094/pdis-12-19-2617-sr] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Soybean production has expanded worldwide including countries in sub-Saharan Africa. Several national and international agencies and research groups have partnered to improve overall performance of soybean breeding stocks and have introduced new germplasm from Brazil and the United States with the goal of developing new high-yielding cultivars. Part of this effort has been to test improved soybean lines/cultivars accumulated from private and public sources in multilocational trials in sub-Saharan Africa. These trials are known as the Pan-African Soybean Variety Trials, and the entries come from both private and public breeding programs. The objective of this research was to evaluate entries in the trials that include commercial cultivars or advanced experimental lines for the incidence and severity of foliar diseases. All trials were planted in December 2018 with six located in Zambia and one in Malawi. Plants were evaluated during the reproductive growth stages using a visual pretransformed severity rating scale. Foliar disease ratings were recorded for three bacterial diseases, six fungal diseases, one oomycete, and viruses. The overall occurrence of most of the diseases was high except for soybean rust and target spot, which were only found at two and one location, respectively. However, disease severity was generally low, although there were differences in disease severity ratings among the entries at some of the locations for brown spot, downy mildew, frogeye leaf spot, red leaf blotch, and soybean rust.
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Affiliation(s)
| | - Godfree Chigeza
- International Institute of Tropical Agriculture-IITA SARAH Campus, Lusaka, Zambia
| | | | | | - Brian D Diers
- Department of Crop Sciences, University of Illinois Urbana, Urbana, IL 61801, U.S.A
| | - Harun M Murithi
- USDA, Agricultural Research Service, Urbana, IL 61801, U.S.A
| | - Glen L Hartman
- Department of Crop Sciences, University of Illinois Urbana, Urbana, IL 61801, U.S.A
- USDA, Agricultural Research Service, Urbana, IL 61801, U.S.A
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28
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Kandel YR, Bradley CA, Chilvers MI, Mathew FM, Tenuta AU, Smith DL, Wise KA, Mueller DS. Relationship Between Sudden Death Syndrome caused by Fusarium virguliforme and Soybean Yield: A Meta-Analysis. Plant Dis 2020; 104:1736-1743. [PMID: 32289247 DOI: 10.1094/pdis-11-19-2441-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
In total, 52 uniform field experiments were conducted in Illinois, Indiana, Iowa, Michigan, South Dakota, and Wisconsin in the United States and Ontario, Canada from 2013 to 2017 comparing crop protection products against sudden death syndrome (SDS) of soybean. Data were analyzed using meta-analytic models to summarize the relationship between foliar disease index (FDX) and yield. For each study, correlation and regression analyses were performed separately to determine three effect sizes: Fisher's transformation of correlation coefficients (Z r ), intercept (β0), and slope (β1). Random- and mixed-effect meta-analyses were used to summarize the effect sizes. Study- and location-specific moderator variables FDX (low < 10% and high ≥ 10%), date of planting (early = prior to 7 May, conventional = 7 to 21 May, and late = after 21 May) cultivar (susceptible and partially resistant to SDS), study location, and growing season were used as fixed effects. The overall mean effect sizes of transformed correlation coefficient [Formula: see text] r was -0.41 and different from zero (P < 0.001), indicating that yield was negatively correlated with FDX. The [Formula: see text] r was affected by disease level (P < 0.01) and cultivar (P = 0.02), with a greater effect at higher disease levels and with susceptible cultivars. The mean [Formula: see text] 0 was 4,121 kg/ha and mean [Formula: see text] 1 was -21 kg/ha/% FDX and were different from zero (P < 0.01). Results from these data indicate that, for every unit of FDX increase, yield was decreased by 0.5%. Study locations and year affected the [Formula: see text] 0 , whereas none of the moderator variables significantly affected [Formula: see text] 1.
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Affiliation(s)
- Yuba R Kandel
- Department of Plant Pathology and Microbiology, Iowa State University, Ames 50011, U.S.A
| | - Carl A Bradley
- Department of Plant Pathology, University of Kentucky Research and Education Center, Princeton 42445, U.S.A
| | - Martin I Chilvers
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing 48824, U.S.A
| | - Febina M Mathew
- Department of Agronomy, Horticulture and Plant Science, South Dakota State University, Brookings 57007, U.S.A
| | - Albert U Tenuta
- Ontario Ministry of Agriculture, Food, and Rural Affairs, Ridgetown, ON N0P2C0, Canada
| | - Damon L Smith
- Department of Plant Pathology, University of Wisconsin-Madison, Madison, 53706, U.S.A
| | - Kiersten A Wise
- Department of Plant Pathology, University of Kentucky Research and Education Center, Princeton 42445, U.S.A
| | - Daren S Mueller
- Department of Plant Pathology and Microbiology, Iowa State University, Ames 50011, U.S.A
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29
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Shahoveisi F, Del Río Mendoza LE. Effect of Wetness Duration and Incubation Temperature on Development of Ascosporic Infections by Sclerotinia sclerotiorum. Plant Dis 2020; 104:1817-1823. [PMID: 32208061 DOI: 10.1094/pdis-06-19-1304-re] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The impact of wetness duration and incubation temperatures on Sclerotinia sclerotiorum ascospore germination and ascosporic infection efficiency were evaluated. Ascospore germination was optimal when incubated in continuous moisture (free water) at 21°C. Significantly lower germination was observed at 10 or 30°C. Interrupting ascospore wet incubation was detrimental for germination. In infection efficiency studies, dry bean and canola flowers were inoculated with dry ascospores and placed on leaves of dry bean and canola plants, respectively. Dry bean plants were incubated for 196 h at 18 to 20°C in alternating 8 to 16 h wet/12 to 24 h dry periods. Canola plants were incubated for 240 h at 10, 15, 20, 25, or 30°C in alternating 6 to 18 h wet/18 to 6 h dry periods. Interrupting wet incubation delayed symptom appearance and hindered development of the epidemics on both plant types. Logistic regression models estimated at 50% the probability of disease development on dry bean and canola plants when 68 and 48 h of wet incubation at 20°C accumulated in a period of 6 days, respectively. The canola model was validated using data from field trials. Results of these studies will contribute to develop more accurate warning models for diseases caused by S. sclerotiorum.
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Affiliation(s)
- F Shahoveisi
- Department of Plant Pathology, North Dakota State University, Fargo, ND 58108
| | - L E Del Río Mendoza
- Department of Plant Pathology, North Dakota State University, Fargo, ND 58108
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30
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Roth MG, Jacobs JL, Napieralski S, Byrne AM, Stouffer-Hopkins A, Warner F, Chilvers MI. Fluopyram Suppresses Population Densities of Heterodera glycines in Field and Greenhouse Studies in Michigan. Plant Dis 2020; 104:1305-1311. [PMID: 32155114 DOI: 10.1094/pdis-04-19-0874-re] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The soybean cyst nematode (SCN), Heterodera glycines Ichinohe, causes significant damage to soybean production annually. Fluopyram is a fungicide commonly used in soybean seed treatments intended to control soilborne fungal pathogens; however, recent studies have also suggested inhibitory effects on SCN. We examined the effects of a fluopyram seed treatment, ILeVO, on SCN reproduction, sudden death syndrome (SDS) development, and yield in a 3-year field study. Overall, fluopyram had a significant effect on yield (P = 0.046) and end-of-season SCN eggs and second-stage juveniles (Pf, P = 0.033) but no significant effect on SCN reproduction (Rf) or SDS disease index (P > 0.05). Post hoc tests indicated that fluopyram increased yield and suppressed SCN quantities. However, Rf was consistently greater than 1 whether or not the seed was treated with fluopyram, indicating that SCN populations were still increasing in the presence of fluopyram. A follow-up greenhouse study indicated that fluopyram reduced SCN relative to nontreated controls, as observed in the field, but only reduced SCN DNA within roots of a susceptible cultivar. These results indicate that fluopyram can suppress SCN quantities relative to nontreated seed but may not successfully reduce nematode populations without the use of additional management strategies.
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Affiliation(s)
- M G Roth
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
- Genetics Graduate Program, Michigan State University, East Lansing, MI 48824, U.S.A
| | - J L Jacobs
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
| | - S Napieralski
- Department of Geoscience, University of Wisconsin-Madison, Madison, WI 53706, U.S.A
| | - A M Byrne
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
| | - A Stouffer-Hopkins
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
| | - F Warner
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
| | - M I Chilvers
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI 48824, U.S.A
- Genetics Graduate Program, Michigan State University, East Lansing, MI 48824, U.S.A
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31
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Scott K, Eyre M, McDuffee D, Dorrance AE. The Efficacy of Ethaboxam as a Soybean Seed Treatment Toward Phytophthora, Phytopythium, and Pythium in Ohio. Plant Dis 2020; 104:1421-1432. [PMID: 32191161 DOI: 10.1094/pdis-09-19-1818-re] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Phytophthora, Phytopythium, and Pythium species that cause early-season seed decay and pre-emergence and post-emergence damping off of soybean are most commonly managed with seed treatments. The phenylamide fungicides metalaxyl and mefenoxam, and ethaboxam are effective toward some but not all species. The primary objective of this study was to evaluate the efficacy of ethaboxam in fungicide mixtures and compare those with other fungicides as seed treatments to protect soybean against Pythium, Phytopythium, and Phytophthora species in both high-disease field environments and laboratory seed plate assays. The second objective was to evaluate these seed treatment mixtures on cultivars that have varying levels and combinations of resistance to these soilborne pathogens. Five of eight environments received adequate precipitation in the 14 days after planting for high levels of seedling disease development and treatment evaluations. Three environments had significantly greater stands, and three had significantly greater yield when ethaboxam was used in the seed treatment mixture compared with treatments containing metalaxyl or mefenoxam alone. Three fungicide formulations significantly reduced disease severity compared with nontreated in the seed plate assay for 17 species. However, the combination of ethaboxam plus metalaxyl in a mixture was more effective than either fungicide alone against some Pythium and Phytopythium species. Overall, our results indicate that the addition of ethaboxam to a fungicide seed treatment is effective in reducing seed rot caused by these pathogens commonly isolated from soybean in Ohio but that these effects can be masked when cultivars with resistance are planted.
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Affiliation(s)
- Kelsey Scott
- Department of Plant Pathology, The Ohio State University, Wooster, OH 44691
| | - Meredith Eyre
- Department of Plant Pathology, The Ohio State University, Wooster, OH 44691
| | | | - Anne E Dorrance
- Department of Plant Pathology, The Ohio State University, Wooster, OH 44691
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32
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Hu S, Xu Q, Zhang Y, Zhu F. Stimulatory Effects of Boscalid on Virulence of Sclerotinia sclerotiorum Indicate Hormesis May Be Masked by Inhibitions. Plant Dis 2020; 104:833-840. [PMID: 31940448 DOI: 10.1094/pdis-07-19-1421-re] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Hormetic effects of fungicides on phytopathogens are of great importance for proper application of fungicides. The aim of the present study was to investigate the stimulatory effects of the fungicide boscalid on mycelial growth and virulence of the devastating plant pathogen Sclerotinia sclerotiorum. Boscalid in potato dextrose agar (PDA) at a dosage range from 0.0005 to 0.002 μg/ml exerted statistically significant (P ≤ 0.015) stimulations on mycelial growth of S. sclerotiorum, and the maximum stimulation magnitudes were 5.55 ± 0.73% (mean ± SD) for the four isolates tested. Boscalid in PDA at 0.02 μg/ml inhibited mycelial growth of isolates HLJ3H and HLJ4H by 15.0 and 8.9%, respectively. However, after the growth-inhibited mycelia were inoculated on rapeseed leaves, isolates HLJ3H and HLJ4H exhibited virulence stimulations of 8.7 and 17.8%, respectively, indicating that hormesis may be masked by inhibitions. Boscalid sprayed at 0.0001 to 0.1 μg/ml on detached rapeseed leaves had significant (P ≤ 0.041) stimulations on virulence of S. sclerotiorum, and the maximum stimulation magnitudes were 17.90 ± 5.94% (mean ± SD) for the four isolates tested. Experiments on 12 isolates with different levels of virulence showed there was a negative correlation (R = -0.663, P = 0.019) between the maximum virulence stimulation magnitude and virulence of S. sclerotiorum in the absence of fungicide. Boscalid at stimulatory concentrations had no significant effect on the expression levels of three virulence-associated genes that encode cutinase (SsCut), polygalacturonase (SsPG1), and oxaloacetate acetylhydrolase (SsOah1). The molecular mechanisms for hormetic effects of boscalid on S. sclerotiorum remain to be studied in the future.
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Affiliation(s)
- Simin Hu
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Qianru Xu
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yuchao Zhang
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Fuxing Zhu
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
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33
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Elverson TR, Kontz BJ, Markell SG, Harveson RM, Mathew FM. Quantitative PCR Assays Developed for Diaporthe helianthi and Diaporthe gulyae for Phomopsis Stem Canker Diagnosis and Germplasm Screening in Sunflower ( Helianthus annuus). Plant Dis 2020; 104:793-800. [PMID: 31951508 DOI: 10.1094/pdis-09-19-1827-re] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Phomopsis stem canker of sunflower is caused by two fungal pathogens, Diaporthe helianthi and Diaporthe gulyae, in the United States. In this study, two quantitative PCR (qPCR) assays were developed to detect and quantify D. helianthi and D. gulyae in sunflower. The two assays differentiated the two fungi from each other, other species of the genus Diaporthe, and pathogens, and they have high efficiency (>90%). The qPCR assays detected the two pathogens on plant samples exhibiting Phomopsis stem canker symptoms sampled from commercial sunflower fields in Minnesota, Nebraska, North Dakota, and South Dakota. Furthermore, the assays were used to screen cultivated sunflower accessions for resistance to D. helianthi and D. gulyae. The disease severity index (DSI) of the accessions significantly correlated (P < 0.0001) with the amount of pathogen DNA from the qPCR assays. The qPCR assays identified PI664232 and PI561918 to be significantly less susceptible (P ≤ 0.05) to D. helianthi and D. gulyae, respectively, when compared with the susceptible check cultivar HA 288, and this was in agreement with the DSI. These results suggest that the qPCR assays for D. helianthi and D. gulyae can be used as a reliable tool to diagnose Phomopsis stem canker and screen sunflower germplasm for disease resistance.
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Affiliation(s)
- Taylor R Elverson
- Department of Agronomy, Horticulture, and Plant Science, South Dakota State University, Brookings, SD 57007
| | - Brian J Kontz
- Department of Agronomy, Horticulture, and Plant Science, South Dakota State University, Brookings, SD 57007
| | - Samuel G Markell
- Department of Plant Pathology, North Dakota State University, Fargo, ND 58102
| | - Robert M Harveson
- Department of Plant Pathology, University of Nebraska-Lincoln, Scottsbluff, NE 69361
| | - Febina M Mathew
- Department of Agronomy, Horticulture, and Plant Science, South Dakota State University, Brookings, SD 57007
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Roth MG, Oudman KA, Griffin A, Jacobs JL, Sang H, Chilvers MI. Diagnostic qPCR Assay to Detect Fusarium brasiliense, a Causal Agent of Soybean Sudden Death Syndrome and Root Rot of Dry Bean. Plant Dis 2020; 104:246-254. [PMID: 31644390 DOI: 10.1094/pdis-01-19-0016-re] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Species within clade 2 of the Fusarium solani species complex (FSSC) are significant pathogens of dry bean (Phaseolus vulgaris) and soybean (Glycine max), causing root rot and/or sudden death syndrome (SDS). These species are morphologically difficult to distinguish and often require molecular tools for proper diagnosis to a species level. Here, a TaqMan probe-based quantitative PCR (qPCR) assay was developed to distinguish Fusarium brasiliense from other closely related species within clade 2 of the FSSC. The assay displays high specificity against close relatives and high sensitivity, with a detection limit of 100 fg. This assay was able to detect F. brasiliense from purified mycelia, infected dry bean roots, and soil samples throughout Michigan. When multiplexed with an existing qPCR assay specific to Fusarium virguliforme, accurate quantification of both F. brasiliense and F. virguliforme was obtained, which can facilitate accurate diagnoses and identify coinfections with a single reaction. The assay is compatible with multiple qPCR thermal cycling platforms and will be helpful in providing accurate detection of F. brasiliense. Management of root rot and SDS pathogens in clade 2 of the FSSC is challenging and must be done proactively, because no midseason management strategies currently exist. However, accurate detection can facilitate management decisions for subsequent growing seasons to successfully manage these pathogens.
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Affiliation(s)
- Mitchell G Roth
- Department of Plant, Soil and Microbial Sciences Michigan State University, East Lansing, MI 48824
- Genetics Graduate Program, Michigan State University, East Lansing, MI 48824
| | - Kjersten A Oudman
- Department of Plant, Soil and Microbial Sciences Michigan State University, East Lansing, MI 48824
| | - Amanda Griffin
- Department of Plant, Soil and Microbial Sciences Michigan State University, East Lansing, MI 48824
| | - Janette L Jacobs
- Department of Plant, Soil and Microbial Sciences Michigan State University, East Lansing, MI 48824
| | - Hyunkyu Sang
- Department of Plant, Soil and Microbial Sciences Michigan State University, East Lansing, MI 48824
| | - Martin I Chilvers
- Department of Plant, Soil and Microbial Sciences Michigan State University, East Lansing, MI 48824
- Genetics Graduate Program, Michigan State University, East Lansing, MI 48824
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Fu H, Yang Y, Mishra V, Zhou Q, Zuzak K, Feindel D, Harding MW, Feng J. Most Plasmodiophora brassicae Populations in Single Canola Root Galls from Alberta Fields are Mixtures of Multiple Strains. Plant Dis 2020; 104:116-120. [PMID: 31644392 DOI: 10.1094/pdis-06-19-1235-re] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Clubroot, caused by Plasmodiophora brassicae, is an important disease on canola in Alberta, Canada. The pathogen is grouped into pathotypes according to their virulence reaction on differential hosts. Multiple pathotypes or strains are known exist in one field, one plant, or even one gall. This study was conducted with the objective of testing the prevalence of the coexistence of multiple strains in a single gall. In all, 79 canola clubroot galls were collected from 22 fields across Northern Alberta in 2018. Genomic DNA extracted from these single galls was analyzed using RNase H-dependent PCR (rhPCR). The rhPCR primers were designed to amplify a partial sequence of a dimorphic gene, with one primer pair specific to one sequence and the other primer pair specific to the alternative sequence. The amplification of both sequences from DNA obtained from a single gall would indicate that it contains two different P. brassicae strains. The rhPCR analyses indicated that the P. brassicae populations in 50 of the 79 galls consisted of more than one strain. This result emphasizes the need for cautious interpretation of results when a single-gall population is subject to pathotyping or being used as inoculum in plant pathology research. It also confirms that the maintenance of pathotype diversity within single root galls is a common occurrence which has implications for the durability, and stewardship, of single-gene host resistance.
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Affiliation(s)
- Heting Fu
- Alberta Plant Health Lab, Crop Diversification Centre North, Alberta Agriculture and Forestry, Edmonton, AB, T5Y 6H3, Canada
| | - Yalong Yang
- Alberta Plant Health Lab, Crop Diversification Centre North, Alberta Agriculture and Forestry, Edmonton, AB, T5Y 6H3, Canada
| | - Vachaspati Mishra
- Alberta Plant Health Lab, Crop Diversification Centre North, Alberta Agriculture and Forestry, Edmonton, AB, T5Y 6H3, Canada
| | - Qixing Zhou
- Alberta Plant Health Lab, Crop Diversification Centre North, Alberta Agriculture and Forestry, Edmonton, AB, T5Y 6H3, Canada
| | - Krista Zuzak
- Alberta Plant Health Lab, Crop Diversification Centre North, Alberta Agriculture and Forestry, Edmonton, AB, T5Y 6H3, Canada
| | - David Feindel
- Crop Diversification Centre North, Alberta Agriculture and Forestry, Edmonton, AB, T5Y 6H3, Canada
| | - Michael W Harding
- Crop Diversification Centre South, Alberta Agriculture and Forestry, Brooks, AB, T1R 1E6, Canada
| | - Jie Feng
- Alberta Plant Health Lab, Crop Diversification Centre North, Alberta Agriculture and Forestry, Edmonton, AB, T5Y 6H3, Canada
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de Paiva BAR, Wendland A, Teixeira NC, Ferreira MASV. Rapid Detection of Xanthomonas citri pv. fuscans and Xanthomonas phaseoli pv. phaseoli in Common Bean by Loop-Mediated Isothermal Amplification. Plant Dis 2020; 104:198-203. [PMID: 31738688 DOI: 10.1094/pdis-02-19-0325-re] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A single loop-mediated isothermal amplification (LAMP) assay was developed for specific detection of both pathogens that cause bacterial blight in common bean, Xanthomonas phaseoli pv. phaseoli (Xpp) and Xanthomonas citri pv. fuscans (Xcf). The objective was to provide a simple, easy-to-use, specific, and sensitive method to investigate the presence of one or both pathogens in plant material and seeds for routine diagnosis. The detection limits for both pathogens were 10 CFU/ml for cell suspensions and 1 fg of DNA, whereas in conventional PCR, the primers detected up to 105 CFU/ml and 1 ng of DNA. Specificity was confirmed by testing DNA from bean leaves, other Xanthomonas species, common fungal and bacterial bean pathogens, and bacteria from the leaf microbiota. The method was tested with bean leaves inoculated with Xpp, and the pathogen could be detected from 4 h up to 15 days postinoculation, even before disease symptoms were visible. When the method was applied to bacterium detection (Xpp or Xcf) in seed lots from infected plants, the bacterium detection rate was 100% (24 of 24). The pathogens were detected in seeds incubated for just 1 h in saline solution (0.85%), reducing the time needed for bacterium detection. The LAMP assay could be useful as a tool in bean bacterial blight management. Rapid and sensitive detection of bacteria in bean seed lots would reduce the risks of planting highly contaminated seeds in environments favorable to blight multiplication.
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Affiliation(s)
| | - Adriane Wendland
- Embrapa Arroz e Feijão, 75375-000 Santo Antônio de Goiás, Goiás, Brazil
| | | | - Marisa A S V Ferreira
- Department of Plant Pathology, University of Brasilia, 70910-900 Brasilia, Distrito Federal, Brazil
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Pérez-Hernández O, Giesler LJ, Hilbe JM. A Negative Binomial Regression Model of the Observed Population Density of Heterodera glycines after Annual Corn Rotation in Nebraska. Plant Dis 2019; 103:3093-3100. [PMID: 31613191 DOI: 10.1094/pdis-03-19-0681-re] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
In Nebraska, rotation of soybean (Glycine max) fields to corn (Zea mays) is a major practice to manage the soybean cyst nematode (SCN; Heterodera glycines). However, factors associated with SCN population density decline during corn rotation are not clearly defined. This study addresses that question using a modeling approach. Seventy-nine fields were sampled in 2009, 2010, and 2011 to determine SCN population densities (eggs/100 cm3 of soil) before and after rotation. After rigorous field screening and model testing and validation, the regression model Log(Pf)^=-2.3360+0.8368LogPi+0.4333pH was developed, where Log Pf is the natural log of SCN eggs at the end of the rotation year, Pi is the population density before rotation, and pH is the soil pH. Model goodness-of-fit was assessed through residual analysis, information criteria, and other remedial measures. Model overdispersion was 1.04. Validation in a 50 and a 75% random sample from the original data set showed little change in model regression coefficients, standard errors, and associated significance, confirming model fit and performance. The model indicates that for one-unit increase in soil pH, SCN Pf is expected to increase by 53.7% at constant Pi, and correspondingly, a 10% change in Pi will result in about 8.3% change in Pf at constant soil pH. The model suggested that SCN population levels before corn rotation and soil pH are major determinants of observed SCN population density reduction after annual corn rotation in Nebraska. This model has potential for use in SCN risk analysis and in predicting SCN population decline after corn rotation in the state.
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Affiliation(s)
- Oscar Pérez-Hernández
- School of Agricultural Sciences, Northwest Missouri State University, Maryville, MO 64468
| | - Loren J Giesler
- Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, NE 68583
| | - Joseph M Hilbe
- T. Denny Sanford School of Social and Family Dynamics, Arizona State University, Tempe, AR 85287 (deceased in 2017)
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Abstract
Fusarium oxysporum (Fo) is an important pathogen that reduces soybean yield by causing seedling disease and root rot. This study assessed the effects of pH and temperature on Fo fungal growth and seedling disease. In an in vitro assay, 14 Fo isolates collected from symptomatic soybean roots across Iowa in 2007 were grown on artificial culture media at five pH levels (4, 5, 6, 7, and 8) and incubated at four temperatures (15, 20, 25, or 30°C). In a rolled-towel assay, soybean seeds from Fo-susceptible cultivar Jack were inoculated with a suspension of a pathogenic or a nonpathogenic Fo isolate; both isolates were previously designated for their relative aggressiveness in causing root rot at 25°C. The seeds were placed in rolled germination paper, and the rolls were incubated in all combinations of buffer solutions at four pH levels (4, 5, 6, and 7), and four temperatures (15, 20, 25, or 30°C). There was a significant interaction between temperature and pH (P < 0.05) for in vitro radial growth and root rot severity. Isolates showed the most in vitro radial growth after incubation at pH 6 and 25°C. For the rolled-towel assay, the pathogenic isolate caused the most severe root rot at pH 6 and 30°C. Gaussian regression analysis estimates for optimal conditions were pH 6.3 at 27.1°C for maximal fungal growth and pH 5.9 at 30°C for maximal root rot severity. These results indicate that optimal pH and temperature conditions are similar for Fo growth and disease in soybean seedlings and suggest that Fo may be a more important seedling pathogen when soybeans are planted under warm conditions in moderately acidic soils.
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Affiliation(s)
- David R Cruz
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA 50011
| | - Leonor F S Leandro
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA 50011
| | - Gary P Munkvold
- Department of Plant Pathology and Microbiology, Iowa State University, Ames, IA 50011
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Fulmer AM, Mehra LK, Kemerait RC, Brenneman TB, Culbreath AK, Stevenson KL, Cantonwine EG. Relating Peanut Rx Risk Factors to Epidemics of Early and Late Leaf Spot of Peanut. Plant Dis 2019; 103:3226-3233. [PMID: 31573431 DOI: 10.1094/pdis-10-18-1782-re] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Previous research has demonstrated the efficacy of prescription fungicide programs, based upon Peanut Rx, to reduce combined effects of early leaf spot (ELS), caused by Passalora arachidicola (Cercospora arachidicola), and late leaf spot (LLS), caused by Nothopassalora personata (syn. Cercosporidium personatum), but the potential of Peanut Rx to predict each disease has never been formally evaluated. From 2010 to 2016, non-fungicide-treated peanut plots in Georgia and Florida were sampled to monitor the development of ELS and LLS. This resulted in 168 cases (unique combinations of Peanut Rx risk factors) with associated total leaf spot risk points ranging from 40 to 100. Defoliation ranged from 13.9 to 100%, and increased significantly with increasing total risk points (conditional R2 = 0.56; P < 0.001). Leaf spot onset (time in days after planting [DAP] when either leaf spot reached 1% lesion incidence), ELS onset, and LLS onset ranged from 29 to 140, 29 to 142, and 50 to 143 DAP, respectively, and decreased significantly with increasing risk points. Standardized AUDPC of ELS was significantly affected by risk points (conditional R2 = 0.53, P < 0.001), but not for LLS. After removing redundant Peanut Rx factors, planting date, rotation, historical leaf spot prevalence, cultivar, and field history were used as fixed effects in mixed effect regression models to evaluate their contribution to leaf spot, ELS or LLS prediction. Results from mixed effects regression confirmed that the selected Peanut Rx risk factors contributed to the variability of at least one measurement of development of combined or separate epidemics of ELS and LLS, but not all factors affected ELS and LLS equally. Historical leaf spot prevalence, a new potential preplant risk factor, was a consistent predictor of the dominant disease(s) observed in the field. Results presented here demonstrate that Peanut Rx is a very effective tool for predicting leaf spot onset regardless of which leaf spot is predominant, but also suggest that associated risk does not reflect the same development for each disease. These data will be useful for refining thresholds for differentiating high, moderate, and low risk fields, and reevaluating the timing of fungicide applications in reduced input programs with respect to disease onset.
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Affiliation(s)
- Abraham M Fulmer
- Department of Plant Pathology, The University of Georgia, Tifton, GA 31793
| | - Lucky K Mehra
- Department of Plant Pathology, Kansas State University, Manhattan, KS 66506
| | - Robert C Kemerait
- Department of Plant Pathology, The University of Georgia, Tifton, GA 31793
| | | | - Albert K Culbreath
- Department of Plant Pathology, The University of Georgia, Tifton, GA 31793
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Standish JR, Culbreath AK, Branch WD, Brenneman TB. Disease and Yield Response of a Stem-rot-resistant and -Susceptible Peanut Cultivar under Varying Fungicide Inputs. Plant Dis 2019; 103:2781-2785. [PMID: 31469362 DOI: 10.1094/pdis-04-19-0771-re] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Peanut (Arachis hypogaea L.) producers rely on costly fungicide programs to manage stem rot, caused by Sclerotium rolfsii. Planting disease-resistant cultivars could increase profits by allowing for the deployment of less-expensive, lower-input fungicide programs. Field experiments were conducted to characterize stem rot and early and late leaf spot (caused by Passalora arachidicola and Nothopassalora personata, respectively), yield, and overall profitability of cultivars Georgia-06G (stem-rot-susceptible) and Georgia-12Y (stem-rot-resistant) as influenced by seven commercial fungicide programs. Stem rot incidence was consistently lower on Georgia-12Y for all fungicides when compared with Georgia-06G and was lowest for both cultivars in plots treated with prothioconazole plus a tank mixture of penthiopyrad and tebuconazole. Leaf spot severity was similar for both the resistant and susceptible cultivars, and the greatest reduction occurred in plots treated with prothioconazole plus a tank mixture of penthiopyrad and tebuconazole. Fungicide programs gave similar yield and net return on Georgia-12Y; however, plots of Georgia-06G treated with prothioconazole plus a tank mixture of penthiopyrad and tebuconazole had the greatest yield and net return. Yields and economic return from the highest level of fungicide inputs on Georgia-06G were numerically less than those of Georgia-12Y treated with only chlorothalonil. These results show the value of fungicides in peanut disease management with susceptible cultivars, as well as the benefits of planting stem-rot-resistant cultivars in high-risk situations.
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Affiliation(s)
- J R Standish
- Department of Plant Pathology, The University of Georgia, Tifton, GA 31793
| | - A K Culbreath
- Department of Plant Pathology, The University of Georgia, Tifton, GA 31793
| | - W D Branch
- Department of Crop and Soil Science, The University of Georgia, Tifton, GA 31793
| | - T B Brenneman
- Department of Plant Pathology, The University of Georgia, Tifton, GA 31793
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Hartman GL, McCormick SP, O'Donnell K. Trichothecene-Producing Fusarium Species Isolated from Soybean Roots in Ethiopia and Ghana and their Pathogenicity on Soybean. Plant Dis 2019; 103:2070-2075. [PMID: 31215854 DOI: 10.1094/pdis-12-18-2286-re] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Numerous pathogen surveys have reported that diverse Fusarium spp. threaten soybean production in North and South America. However, little research has been conducted to characterize Fusarium pathogens of soybean in sub-Saharan Africa. Our objectives were to (i) identify Fusarium spp. isolated from discolored root segments of soybean grown in Ethiopia and Ghana using DNA sequence data, (ii) determine whether isolates nested in the Fusarium incarnatum-equiseti and F. sambucinum species complexes (FIESC and FSAMSC, respectively) produced trichothecene mycotoxins in vitro, and (iii) test these isolates for pathogenicity on soybean. Molecular phylogenetic analyses revealed that the trichothecene mycotoxin-producing isolates comprised three undescribed species within the FIESC and FSAMSC. Mycotoxin type B trichothecene 4,15-diacetylnivalenol or T-2 toxin and related type A neosolaniol trichothecenes were produced by 18 of the 21 isolates. Of the 12 isolates from Ethiopia and Ghana tested for their impact on seed germination, 5, comprising two undescribed phylospecies (i.e., Fusarium sp. number 3 and Fusarium sp. FIESC 2,) completely inhibited germination, whereas 4 caused no reduction in germination. Root lesions induced by all 12 isolates were greater than the uninoculated negative control. Additional variation among the isolates was reflected in differences (α = 0.05) in lesion lengths, which ranged from 34 to 67% of total root length. This is the first report characterizing FIESC and FSAMSC isolates from soybean roots in Ethiopia and Ghana.
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Affiliation(s)
- Glen L Hartman
- 1United States Department of Agriculture-Agricultural Research Service (USDA-ARS) and Department of Crop Sciences, National Soybean Research Center, University of Illinois, Urbana, IL 61801-4733
| | - Susan P McCormick
- 2Mycotoxin Prevention and Applied Microbiology Research Unit, USDA-ARS, Peoria, IL 61604-3999
| | - Kerry O'Donnell
- 2Mycotoxin Prevention and Applied Microbiology Research Unit, USDA-ARS, Peoria, IL 61604-3999
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Kandel YR, Bradley CA, Chilvers MI, Mathew FM, Tenuta AU, Smith DL, Wise KA, Mueller DS. Effect of Seed Treatment and Foliar Crop Protection Products on Sudden Death Syndrome and Yield of Soybean. Plant Dis 2019; 103:1712-1720. [PMID: 31059383 DOI: 10.1094/pdis-12-18-2199-re] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Sudden death syndrome (SDS), caused by Fusarium virguliforme, is an important soilborne disease of soybean. Risk of SDS increases when cool and wet conditions occur soon after planting. Recently, multiple seed treatment and foliar products have been registered and advertised for management of SDS but not all have been tested side by side in the same field experiment at multiple field locations. In 2015 and 2016, seed treatment fungicides fluopyram and thiabendazole; seed treatment biochemical pesticides citric acid and saponins extract of Chenopodium quinoa; foliar fungicides fluoxastrobin + flutriafol; and an herbicide, lactofen, were evaluated in Illinois, Indiana, Iowa, Michigan, South Dakota, Wisconsin, and Ontario for SDS management. Treatments were tested on SDS-resistant and -susceptible cultivars at each location. Overall, fluopyram provided the highest level of control of root rot and foliar symptoms of SDS among all the treatments. Foliar application of lactofen reduced foliar symptoms in some cases but produced the lowest yield. In 2015, fluopyram reduced the foliar disease index (FDX) by over 50% in both resistant and susceptible cultivars and provided 8.9% yield benefit in susceptible cultivars and 3.5% yield benefit in resistant cultivars compared with the base seed treatment (control). In 2016, fluopyram reduced FDX in both cultivars by over 40% compared with the base seed treatment. For yield in 2016, treatment effect was not significant in the susceptible cultivar while, in the resistant cultivar, fluopyram provided 3.5% greater yield than the base seed treatment. In this study, planting resistant cultivars and using fluopyram seed treatment were the most effective tools for SDS management. However, plant resistance provided an overall better yield-advantage than using fluopyram seed treatment alone. Effective seed treatments can be an economically viable consideration to complement resistant cultivars for managing SDS.
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Affiliation(s)
- Yuba R Kandel
- 1 Department of Plant Pathology and Microbiology, Iowa State University, Ames 50011, U.S.A
| | - Carl A Bradley
- 2 Department of Plant Pathology, University of Kentucky Research and Education Center, Princeton 42445, U.S.A
| | - Martin I Chilvers
- 3 Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing 48824, U.S.A
| | - Febina M Mathew
- 4 Department of Agronomy, Horticulture and Plant Science, South Dakota State University, Brookings 57007, U.S.A
| | - Albert U Tenuta
- 5 Ontario Ministry of Agriculture, Food, and Rural Affairs, Ridgetown, ON N0P2C0, Canada
| | - Damon L Smith
- 6 Department of Plant Pathology, University of Wisconsin-Madison, Madison, 53706, U.S.A
| | - Kiersten A Wise
- 2 Department of Plant Pathology, University of Kentucky Research and Education Center, Princeton 42445, U.S.A
| | - Daren S Mueller
- 1 Department of Plant Pathology and Microbiology, Iowa State University, Ames 50011, U.S.A
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