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Pablo-Rodríguez JL, Bravo-Monzón ÁE, Montiel-González C, Benítez-Malvido J, Álvarez-Betancourt S, Ramírez-Sánchez O, Oyama K, Arena-Ortiz ML, Alvarez-Añorve MY, Avila-Cabadilla LD. Linking Anthropogenic Landscape Perturbation to Herbivory and Pathogen Leaf Damage in Tropical Tree Communities. PLANTS (BASEL, SWITZERLAND) 2023; 12:3839. [PMID: 38005736 PMCID: PMC10675074 DOI: 10.3390/plants12223839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 10/31/2023] [Accepted: 11/01/2023] [Indexed: 11/26/2023]
Abstract
Anthropogenic disturbance of tropical humid forests leads to habitat loss, biodiversity decline, landscape fragmentation, altered nutrient cycling and carbon sequestration, soil erosion, pest/pathogen outbreaks, among others. Nevertheless, the impact of these alterations in multitrophic interactions, including host-pathogen and vector-pathogen dynamics, is still not well understood in wild plants. This study aimed to provide insights into the main drivers for the incidence of herbivory and plant pathogen damage, specifically, into how vegetation traits at the local and landscape scale modulate such interactions. For this purpose, in the tropical forest of Calakmul (Campeche, Mexico), we characterised the foliar damage caused by herbivores and pathogens in woody vegetation of 13 sampling sites representing a gradient of forest disturbance and fragmentation in an anthropogenic landscape from well preserved to highly disturbed and fragmented areas. We also evaluated how the incidence of such damage was modulated by the vegetation and landscape attributes. We found that the incidence of damage caused by larger, mobile, generalist herbivores, was more sensitive to changes in landscape configuration, while the incidence of damage caused by small and specialised herbivores with low dispersal capacity was more influenced by vegetation and landscape composition. In relation to pathogen symptoms, the herbivore-induced foliar damage seems to be the main factor related to their incidence, indicating the enormous importance of herbivorous insects in the modulation of disease dynamics across tropical vegetation, as they could be acting as vectors and/or facilitating the entry of pathogens by breaking the foliar tissue and the plant defensive barriers. The incidence of pathogen damage also responded to vegetation structure and landscape configuration; the incidence of anthracnose, black spot, and chlorosis, for example, were favoured in sites surrounded by smaller patches and a higher edge density, as well as those with a greater aggregation of semi-evergreen forest patches. Fungal pathogens were shown to be an important cause of foliar damage for many woody species. Our results indicate that an increasing transformation and fragmentation of the tropical forest of southern Mexico could reduce the degree of specialisation in plant-herbivore interactions and enhance the proliferation of generalist herbivores (chewers and scrapers) and of mobile leaf suckers, and consequently, the proliferation of some symptoms associated with fungal pathogens such as fungus black spots and anthracnose. The symptoms associated with viral and bacterial diseases and to nutrient deficiency, such as chlorosis, could also increase in the vegetation in fragmented landscapes with important consequences in the health and productivity of wild and cultivated plant species. This is a pioneering study evaluating the effect of disturbances on multitrophic interactions, offering key insights on the main drivers of the changes in herbivory interactions and incidence of plant pathogens in tropical forests.
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Affiliation(s)
- José Luis Pablo-Rodríguez
- Laboratorio de Ecología Funcional de Sistemas Tropicales, Escuela Nacional de Estudios Superiores Unidad Mérida, Universidad Nacional Autónoma de México, Mérida 97357, Mexico; (J.L.P.-R.); (Á.E.B.-M.); (S.Á.-B.); (O.R.-S.)
| | - Ángel E. Bravo-Monzón
- Laboratorio de Ecología Funcional de Sistemas Tropicales, Escuela Nacional de Estudios Superiores Unidad Mérida, Universidad Nacional Autónoma de México, Mérida 97357, Mexico; (J.L.P.-R.); (Á.E.B.-M.); (S.Á.-B.); (O.R.-S.)
| | - Cristina Montiel-González
- Departamento de Ciencias de la Sustentabilidad, El Colegio de la Frontera Sur, San Francisco de Campeche 24500, Mexico;
| | - Julieta Benítez-Malvido
- Laboratorio de Ecología de Hábitats Alterados, Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México, Morelia 58190, Mexico;
| | - Sandra Álvarez-Betancourt
- Laboratorio de Ecología Funcional de Sistemas Tropicales, Escuela Nacional de Estudios Superiores Unidad Mérida, Universidad Nacional Autónoma de México, Mérida 97357, Mexico; (J.L.P.-R.); (Á.E.B.-M.); (S.Á.-B.); (O.R.-S.)
| | - Oriana Ramírez-Sánchez
- Laboratorio de Ecología Funcional de Sistemas Tropicales, Escuela Nacional de Estudios Superiores Unidad Mérida, Universidad Nacional Autónoma de México, Mérida 97357, Mexico; (J.L.P.-R.); (Á.E.B.-M.); (S.Á.-B.); (O.R.-S.)
- Posgrado en Ciencias Biológicas, Unidad de Posgrado, Universidad Nacional Autónoma de México, Ciudad de México 04510, Mexico
| | - Ken Oyama
- Escuela Nacional de Estudios Superiores (ENES) Unidad Morelia, Universidad Nacional Autónoma de México, Morelia 58190, Mexico;
| | - María Leticia Arena-Ortiz
- Laboratorio de Ecogenómica, Facultad de Ciencias, Universidad Nacional Autónoma de México, Parque Científico y Tecnológico, Mérida 97302, Mexico;
| | - Mariana Yólotl Alvarez-Añorve
- Laboratorio de Ecología Funcional de Sistemas Tropicales, Escuela Nacional de Estudios Superiores Unidad Mérida, Universidad Nacional Autónoma de México, Mérida 97357, Mexico; (J.L.P.-R.); (Á.E.B.-M.); (S.Á.-B.); (O.R.-S.)
- Laboratorio de Ecología Funcional de Sistemas Tropicales, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Tlalnepantla de Baz 54090, Mexico
| | - Luis Daniel Avila-Cabadilla
- Laboratorio de Ecología Funcional de Sistemas Tropicales, Escuela Nacional de Estudios Superiores Unidad Mérida, Universidad Nacional Autónoma de México, Mérida 97357, Mexico; (J.L.P.-R.); (Á.E.B.-M.); (S.Á.-B.); (O.R.-S.)
- Laboratorio de Ecología Funcional de Sistemas Tropicales, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Tlalnepantla de Baz 54090, Mexico
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Meno L, Escuredo O, Abuley IK, Seijo MC. Predicting Daily Aerobiological Risk Level of Potato Late Blight Using C5.0 and Random Forest Algorithms under Field Conditions. SENSORS (BASEL, SWITZERLAND) 2023; 23:3818. [PMID: 37112159 PMCID: PMC10146589 DOI: 10.3390/s23083818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Revised: 04/03/2023] [Accepted: 04/06/2023] [Indexed: 06/19/2023]
Abstract
Late blight, caused by Phytophthora infestans, is a major disease of the potato crop with a strong negative impact on tuber yield and tuber quality. The control of late blight in conventional potato production systems is often through weekly application of prophylactic fungicides, moving away from a sustainable production system. In support of integrated pest management practices, machine learning algorithms were proposed as tools to forecast aerobiological risk level (ARL) of Phytophthora infestans (>10 sporangia/m3) as inoculum to new infections. For this, meteorological and aerobiological data were monitored during five potato crop seasons in Galicia (northwest Spain). Mild temperatures (T) and high relative humidity (RH) were predominant during the foliar development (FD), coinciding with higher presence of sporangia in this phenological stage. The infection pressure (IP), wind, escape or leaf wetness (LW) of the same day also were significantly correlated with sporangia according to Spearman's correlation test. ML algorithms such as random forest (RF) and C5.0 decision tree (C5.0) were successfully used to predict daily sporangia levels, with an accuracy of the models of 87% and 85%, respectively. Currently, existing late blight forecasting systems assume a constant presence of critical inoculum. Therefore, ML algorithms offer the possibility of predicting critical levels of Phytophthora infestans concentration. The inclusion of this type of information in forecasting systems would increase the exactitude in the estimation of the sporangia of this potato pathogen.
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Affiliation(s)
- Laura Meno
- Department of Vegetal Biology and Soil Sciences, Faculty of Sciences, University of Vigo, 32004 Ourense, Spain
| | - Olga Escuredo
- Department of Vegetal Biology and Soil Sciences, Faculty of Sciences, University of Vigo, 32004 Ourense, Spain
| | - Isaac K. Abuley
- Department of Agroecology, Flakkebjerg Research Center, Aarhus University, Forsøgsvej 1, 4200 Aarhus, Denmark
| | - M. Carmen Seijo
- Department of Vegetal Biology and Soil Sciences, Faculty of Sciences, University of Vigo, 32004 Ourense, Spain
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3
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Olave-Achury A, Cardenas D, Restrepo S, Lucca F, Fry WE, Myers KL, Danies G, Soto-Suarez M. Phenotypic and Genotypic Characterization of Phytophthora infestans Isolates Associated with Tomato and Potato Crops in Colombia. PHYTOPATHOLOGY 2022; 112:1783-1794. [PMID: 35124971 DOI: 10.1094/phyto-04-21-0158-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Late blight disease, caused by the plant pathogen Phytophthora infestans, is one of the major threats for tomato and potato crops. Monitoring the populations of P. infestans is important to determine if there are changes in the sensitivity to fungicides and host preference. In this study, microsatellite markers and mitochondrial haplotypes were used to assess the genotype of isolates of P. infestans collected from tomato and potato plants in Colombia. Furthermore, sensitivity to the three fungicides cymoxanil (penetrant fungicide), mefenoxam, and fluopicolide (systemic fungicides), and tomato-potato host preference, were evaluated. Mitochondrial haplotyping showed that isolates collected on tomato were from the genetic groups Ia and Ib, while isolates collected on potatoes belonged to group IIa. Microsatellite analyses showed that isolates from tomato form two groups, including the Ib mitochondrial haplotype (which is genetically close to the US-1 clonal lineage) and the Ia haplotype (related to the EC-3 lineage), whereas Colombian isolates from potato formed a separate group. Furthermore, differences in sensitivity to fungicides were observed. Eighty-one percent of the isolates tested were resistant to mefenoxam with an EC50 >10 μg ml-1. Forty-two percent of the isolates showed an intermediate resistance to cymoxanil. The EC50 values ranged between 1 and 10 μg ml-1. For fluopicolide, 90% of the isolates were sensitive, with EC50 <1 μg ml-1. Host preference assays showed that potato isolates infected both host species. Thus, isolates that infect potatoes may pose a risk for tomato crops nearby.
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Affiliation(s)
- Andrea Olave-Achury
- Department of Food and Chemical Engineering, Laboratory of Mycology and Phytopathology, Universidad de los Andes, Bogotá, Colombia 27991
- Corporación Colombiana de Investigación Agropecuaria-AGROSAVIA, Centro de Investigación Tibaitatá, Km 14 Via Mosquera-Bogotá, Cundinamarca, Colombia 250047
| | - Dixon Cardenas
- Department of Food and Chemical Engineering, Laboratory of Mycology and Phytopathology, Universidad de los Andes, Bogotá, Colombia 27991
| | - Silvia Restrepo
- Department of Food and Chemical Engineering, Laboratory of Mycology and Phytopathology, Universidad de los Andes, Bogotá, Colombia 27991
| | - Florencia Lucca
- Instituto Nacional de Tecnología Agropecuaria, Grupo de Investigación en Papa, Estación Experimental Agropecuaria Balcarce, 7620 República Argentina
| | - William E Fry
- School of Integrative Plant Science, Plant Pathology and Plant-Microbe Biology Section, Cornell University, Ithaca, NY 14850, U.S.A
| | - Kevin L Myers
- School of Integrative Plant Science, Plant Pathology and Plant-Microbe Biology Section, Cornell University, Ithaca, NY 14850, U.S.A
| | - Giovanna Danies
- Department of Design, Universidad de los Andes, Bogotá, Colombia 111711
| | - Mauricio Soto-Suarez
- Corporación Colombiana de Investigación Agropecuaria-AGROSAVIA, Centro de Investigación Tibaitatá, Km 14 Via Mosquera-Bogotá, Cundinamarca, Colombia 250047
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Elevating Air Temperature may Enhance Future Epidemic Risk of the Plant Pathogen Phytophthora infestans. J Fungi (Basel) 2022; 8:jof8080808. [PMID: 36012796 PMCID: PMC9410326 DOI: 10.3390/jof8080808] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 07/15/2022] [Accepted: 07/29/2022] [Indexed: 01/27/2023] Open
Abstract
Knowledge of pathogen adaptation to global warming is important for predicting future disease epidemics and food production in agricultural ecosystems; however, the patterns and mechanisms of such adaptation in many plant pathogens are poorly understood. Here, population genetics combined with physiological assays and common garden experiments were used to analyze the genetics, physiology, and thermal preference of pathogen aggressiveness in an evolutionary context using 140 Phytophthora infestans genotypes under five temperature regimes. Pathogens originating from warmer regions were more thermophilic and had a broader thermal niche than those from cooler regions. Phenotypic plasticity contributed ~10-fold more than heritability measured by genetic variance. Further, experimental temperatures altered the expression of genetic variation and the association of pathogen aggressiveness with the local temperature. Increasing experimental temperature enhanced the variation in aggressiveness. At low experimental temperatures, pathogens from warmer places produced less disease than those from cooler places; however, this pattern was reversed at higher experimental temperatures. These results suggest that geographic variation in the thermal preferences of pathogens should be included in modeling future disease epidemics in agricultural ecosystems in response to global warming, and greater attention should be paid to preventing the movement of pathogens from warmer to cooler places.
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The Agro-Meteorological Caused Famines as an Evolutionary Factor in the Formation of Civilisation and History: Representative Cases in Europe. CLIMATE 2020. [DOI: 10.3390/cli9010005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Throughout history, food adequacy has been one of the most critical parameters for the survival of human societies. The prevailing atmospheric conditions have always been recognised as the primary and most uncontrolled factors that determine crop production, both quantitatively and qualitatively. However, this is only a part of the effects chain. In order to assess the magnitude of the potential cultural impacts of weather changes in a region, it is crucial to comprehend the underlying mechanism of successive consequences that relate the proximate causes, which in our case are the adverse Agro-Meteorological Conditions (AMC), to their effects on society. The present study focuses on the analysis of the impacts’ mechanism on human societies. Moreover, several characteristic agro-meteorological events that have led to significant changes in European civilisation are presented as case studies. The results highlight the linkage between weather and its impact on history evolution based on Agro-Meteorological Famine (AMF). The proposed concept and its analysis by the schematic presentation are in corroboration with the documented historical events of European history. Moreover, the presented connections between weather, agricultural production, and society revealed the significant contribution of the short-term adverse weather conditions on the mechanism of the human civilisation evolution.
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Mariette N, Kröner A, Mabon R, Montarry J, Marquer B, Corbière R, Androdias A, Andrivon D. A Trade-Off Between Sporangia Size and Number Exists in the Potato Late Blight Pathogen Phytophthora infestans, and Is Not Altered by Biotic and Abiotic Factors. FRONTIERS IN PLANT SCIENCE 2018; 9:1841. [PMID: 30619410 PMCID: PMC6305756 DOI: 10.3389/fpls.2018.01841] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 11/27/2018] [Indexed: 06/09/2023]
Abstract
The negative relationship between offspring size and number is a classic example of trade-off between life-history traits, reported many times in animal and plant species. Here, we wanted to ascertain whether such a trade-off occurred in the oomycete Phytophthora infestans, and whether it was impacted by biotic and abiotic factors. We thus conducted three infection experiments under controlled conditions and measured the number and the size of sporangia (asexual propagules) produced on potato by different P. infestans isolates. In all experiments, we observed a negative relationship between sporangia size and number, demonstrating the existence of a trade-off. Moreover, although the potato host cultivar, temperature and host of origin (tomato or potato) all affected sporangia number, sporangia size or both, none of these biotic and abiotic factors did change the trade-off. Therefore, the trade-off between sporangia size and number could maintain the polyphenism for these traits in P. infestans populations, and favors the coexistence of distinct reproductive strategies within this species. Our results emphasize the relevance to focus on the relationship between offspring size and number in other fungal plant pathogens, as well as to study the impact of offspring size on fitness-linked traits (virulence and disease lesion development) in these organisms.
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Affiliation(s)
| | | | | | | | | | | | | | - Didier Andrivon
- INRA, UMR1349 Institute for Genetics, Environment and Plant Protection, Le Rheu, France
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Mariette N, Androdias A, Mabon R, Corbière R, Marquer B, Montarry J, Andrivon D. Local adaptation to temperature in populations and clonal lineages of the Irish potato famine pathogen Phytophthora infestans. Ecol Evol 2016; 6:6320-31. [PMID: 27648246 PMCID: PMC5016652 DOI: 10.1002/ece3.2282] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 04/08/2016] [Accepted: 05/27/2016] [Indexed: 01/14/2023] Open
Abstract
Environmental factors such as temperature strongly impact microbial communities. In the current context of global warming, it is therefore crucial to understand the effects of these factors on human, animal, or plant pathogens. Here, we used a common-garden experiment to analyze the thermal responses of three life-history traits (latent period, lesion growth, spore number) in isolates of the potato late blight pathogen Phytophthora infestans from different climatic zones. We also used a fitness index (FI) aggregating these traits into a single parameter. The experiments revealed patterns of local adaptation to temperature for several traits and for the FI, both between populations and within clonal lineages. Local adaptation to temperature could result from selection for increased survival between epidemics, when isolates are exposed to more extreme climatic conditions than during epidemics. We also showed different thermal responses among two clonal lineages sympatric in western Europe, with lower performances of lineage 13_A2 compared to 6_A1, especially at low temperatures. These data therefore stress the importance of thermal adaptation in a widespread, invasive pathogen, where adaptation is usually considered almost exclusively with respect to host plants. This must now be taken into account to explain, and possibly predict, the global distribution of specific lineages and their epidemic potential.
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Affiliation(s)
- Nicolas Mariette
- INRAUMR IGEPP (Institute for Genetics, Environment and Plant Protection)35653Le Rheu CedexFrance
| | - Annabelle Androdias
- INRAUMR IGEPP (Institute for Genetics, Environment and Plant Protection)35653Le Rheu CedexFrance
| | - Romain Mabon
- INRAUMR IGEPP (Institute for Genetics, Environment and Plant Protection)35653Le Rheu CedexFrance
| | - Roselyne Corbière
- INRAUMR IGEPP (Institute for Genetics, Environment and Plant Protection)35653Le Rheu CedexFrance
| | - Bruno Marquer
- INRAUMR IGEPP (Institute for Genetics, Environment and Plant Protection)35653Le Rheu CedexFrance
| | - Josselin Montarry
- INRAUMR IGEPP (Institute for Genetics, Environment and Plant Protection)35653Le Rheu CedexFrance
| | - Didier Andrivon
- INRAUMR IGEPP (Institute for Genetics, Environment and Plant Protection)35653Le Rheu CedexFrance
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Bernard F, Sache I, Suffert F, Chelle M. The development of a foliar fungal pathogen does react to leaf temperature! THE NEW PHYTOLOGIST 2013; 198:232-240. [PMID: 23373986 DOI: 10.1111/nph.12134] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Accepted: 12/06/2012] [Indexed: 06/01/2023]
Abstract
The thermal performance curve is an ecological concept relating the phenotype of organisms and temperature. It requires characterization of the leaf temperature for foliar fungal pathogens. Epidemiologists, however, use air temperature to assess the impacts of temperature on such pathogens. Leaf temperature can differ greatly from air temperature, either in controlled or field conditions. This leads to a misunderstanding of such impacts. Experiments were carried out in controlled conditions on adult wheat plants to characterize the response of Mycosphaerella graminicola to a wide range of leaf temperatures. Three fungal isolates were used. Lesion development was assessed twice a week, whereas the temperature of each leaf was monitored continuously. Leaf temperature had an impact on disease dynamics. The latent period of M. graminicola was related to leaf temperature by a quadratic relationship. The establishment of thermal performance curves demonstrated differences among isolates as well as among leaf layers. For the first time, the thermal performance curve of a foliar fungal pathogen has been established using leaf temperature. The experimental setup we propose is applicable, and efficient, for other foliar fungal pathogens. Results have shown the necessity of such an approach, when studying the acclimatization of foliar fungal pathogens.
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Affiliation(s)
- Frédéric Bernard
- INRA, UMR1091 EGC, F-78850, Thiverval-Grignon, France
- ARVALIS - Institut du Végétal, F-91405, Orsay, France
| | - Ivan Sache
- INRA, UR1290 BIOGER, F-78850, Thiverval-Grignon, France
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Clément JAJ, Magalon H, Glais I, Jacquot E, Andrivon D. To be or not to be solitary: Phytophthora infestans' dilemma for optimizing its reproductive fitness in multiple infections. PLoS One 2012; 7:e37838. [PMID: 22675493 PMCID: PMC3365895 DOI: 10.1371/journal.pone.0037838] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Accepted: 04/25/2012] [Indexed: 01/02/2023] Open
Abstract
The success of parasitic life lies in an optimal exploitation of the host to satisfy key functions directly involved in reproductive fitness. Resource availability generally decreases over time with host mortality, but also during multiple infections, where different strains of parasite share host resources. During multiple infections, the number of parasite strains and their genetic relatedness are known to influence their reproductive rates. Using infections of the potato plant Solanum tuberosum with the parasite Phytophthora infestans, we set up an experimental design to separate dose effects (double- vs. single-site infections) from genetic relatedness (different vs. identical genotypes) on the reproductive fitness of competing parasite genotypes. We showed the existence of two basic response patterns--increase or decrease in reproductive fitness in multiple infections- depending on the parasite genotype. In all cases, the intensity of the response of any genotype depended on the genotype of the competing strain. This diversity of responses to multiple infections is probably maintained by the fluctuating frequencies of multiple infections in nature, arising from variations in disease pressure over the course of an epidemic and between successive epidemics. It allows a rapid response of parasitic populations to changing environments, which are particularly intense in agricultural systems.
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Affiliation(s)
- Julie A J Clément
- Institut of Genetic Environment and Plant Protection, Institut National de la Recherche Agronomique - Agrocampus Ouest - University of Rennes 1, Le Rheu, France.
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Tooley PW, Browning M, Kyde KL, Berner D. Effect of temperature and moisture period on infection of Rhododendron 'Cunningham's White' by Phytophthora ramorum. PHYTOPATHOLOGY 2009; 99:1045-1052. [PMID: 19671006 DOI: 10.1094/phyto-99-9-1045] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We investigated the temperature and moisture conditions that allow Phytophthora ramorum to infect Rhododendron 'Cunningham's White'. Most experiments were performed with a single P. ramorum isolate from the NA1 clonal lineage. For whole plants incubated in dew chambers at 10 to 31 degrees C, the greatest proportion of diseased leaves, 77.5%, occurred at the optimum temperature of 20.5 degrees C. Disease occurred over the entire range of temperatures tested, although amounts of disease were minor at the temperature extremes. For whole plants exposed to varying dew periods at 20 degrees C and then incubated at 20 degrees C for 7 days, a dew period as short as 1 h resulted in a small amount of disease; however, at least 4 h of dew were required for >10% of the leaves to become diseased. Moisture periods of 24 and 48 h resulted in the greatest number of diseased leaves. In detached-leaf, temperature-gradient-plate experiments, incubation at 22 degrees C resulted in the greatest disease severity, followed by 18 degrees C and then 14 degrees C. In detached-leaf, moisture-tent experiments, a 1-h moisture period was sufficient to cause disease on 67 to 73% of leaves incubated for 7 days at 20 degrees C. A statistical model for disease development that combined the effects of temperature and moisture period was generated using nonlinear regression. Our results define temperature and moisture conditions which allow infection by P. ramorum on Cunningham's White rhododendron, and show that P. ramorum is able to infect this host over a wide range of temperatures and moisture levels. The results indicate that P. ramorum has the potential to become established in parts of the United States that are outside its current range.
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Affiliation(s)
- Paul W Tooley
- United States Department of Agriculture-Agricultural Research Service, Foreign Disease-Weed Science Research Unit, 1301 Ditto Avenue, Ft. Detrick, MD 21702-5023, USA.
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