Agave attenuata and Agave amica, new hosts of Tuberose mild mosaic virus in Mexico

Agave attenuata is a Mexican wild plant originally from highlands in the central and occidental mountains of Mexico. This species, known as "swan´s neck agave", is used only as an ornamental plant in public and private gardens. No virus had previously been reported from A. attenuata before this study. In a survey conducted in a commercial greenhouse in Cuautla, Morelos, in 2018, several plants were observed with symptoms of green mosaic and streaks, consistent with a putative viral infection. Sap inoculation from symptomatic A. attenuata plants to herbaceous indicator plants (Nicotiana benthamiana and N. tabacum) failed to produce symptoms in the mechanically inoculated plants. ELISA specific test to CMV, TEV, AMV, TMV and Potyvirus Group (Agdia, Inc.), was positive only for the last one (Chen and Chang, 1998). To determine the identity of the potyvirus involved, total nucleic acid extracts from 100 mg of symptomatic leaves (Trizol reagent; Gibco BRL Life Technologies, England) were used as template in RT-PCR with genus-specific potyvirus primers POT1-POT2, which targeted the variable 5´ terminal half of the coat protein gene of potyviruses (Colinet et al. 1998). The expected 900 bp amplicon was consistently detected in 10 symptomatic A. attenuata plants whereas no PCR products were obtained from 15 asymptomatic A. attenuata plants collected from the "Agaves de México" section at the 'Botanic Garden' of the Instituto de Biología de la UNAM, México. The amplicons were sequenced by the Sanger´s method and the obtained nucleotide (nt) sequences (Acc. No KY190217.1; OP964597-598) and their derived amino acid (aa) sequences were 94.68% to 95.80% similar to an isolate of Tuberose mild mosaic virus (TuMMV; Potyvirus; (Acc. No ON116187.1) characterized from Agave amica in India (Raj et al. 2009). Interestingly, A. amica (formerly Poliantes tuberose) is also a wild Mexican plant that is geographically distributed in the central and south regions of Mexico and is currently being commercially cultivated as an ornamental plant. Plants of A. amica (n=10) showing yellow mild streak were collected from commercial greenhouse and tested positive for TuMMV by RT-PCR and Sanger sequencing (No Acc. OP964599-601 levels) described above. The derived TuMMV sequences from A. attenuata and A. amica were 99-100% similar to each other at the nt/aa level. To exclude the involvement of additional viral agents in the disease, high-throughput sequencing analysis was performed separately for each species of Agave on total RNA extracts from a composite sample of symptomatic leaf tissues using Illumina´s Next Seq 500 platform. Analysis of the obtained 13,260,700 reads (each 75 nt) by the Trinity software, with a total number of sequences of 22,793, resulted in the identification of a single viral contig of 9500 nt for A. attenuata (Acc. No OP964595). Similarly, for A. amica, 27,262,248 reads were obtained, with a total number of sequences of 23,269, resulting in the identification of a single viral contig of 8500 nt (ACC. No OP964602). These contigs showed an identity percentage of 96%/88% and 98%/96% for nucleotides and amino acids, respectively, compared to an isolate of TuMMV from India (Acc. OM293939). Mexico is a center of origin for numerous species of genus Agave which have high economic, social, and ecological impact. TuMMV could be a threat to these plants and potentially to other unknown susceptible crops. To our knowledge, this is the first report of TuMMV in A. attenuata and A. amica in Mexico. REFERENCE Chen, C. C., and Chang, C. A. 1998. Characterization of a potyvirus causing mild mosaic on tuberose. Plant Dis. 82:45-49. Colinet, D., Nguyen, M., Kummert, J., Lepoivre, P., and Xia, F. Z. 1998. Differentiation among potyviruses infecting sweet potato based on genus- and virus-specific reverse transcription polymerase chain reaction. Plant Dis. 82:223-229. Raj, S.K., Snehi, S.K., Kumar, S., Ram, T. and Goel, A.K. 2009. First report of Tuberose mild mosaic potyvirus from tuberose (Polianthes tuberosa L.) in India. Australasian Plant Dis. Notes 4, 93-95.

First Report of Colletotrichum fructicola Causing Anthracnose on Punica granatum in China

Punica granatum L. (Pomegranate), a deciduous shrub, is widely cultivated as a fruit tree and decorative plant in China. Its flowers, leaves, roots and fruit bark also has been widely used for the treatment of different types of human disease because of the high anti-inflammatory and antibacterial activitiy (Tehranifar et al. 2011). In October 2022, leaf spot symptoms were observed on P. granatum leaves in a landscaped area on the campus of Jiangxi Agricultural University (28.75°N, 115.83°E), Nanchang, Jiangxi Province, China. A survey of 40 P. granatum of 300 m2 found that up to 20% of the foliage was infected. Infection normally starts at the tip or edge of the leaves, with the initial symptoms of lesions usually being small dark brown spots (0.8 to 1.5 mm) that gradually expand into irregular spots with grayish white central parts, and brown margins (2.3 to 3.8 mm). Ten freshly infected leaves from three different plants were collected and cut into small slices, disinfected with 75% ethanol for 30 seconds followed by 5% NaClO for 1 minute, rinsed 3 times with sterile water, and then plated on potato dextrose agar (PDA) and incubated in the dark at 25°C. After 7 days, all incubated samples produced similar morphology of aerial mycelium pale grey, dense, and cottony. Conidia were hyaline, smooth-walled, cylindrical, aseptate and measuring 12.28 to 21.05 × 3.51 to 7.37 µm (n = 50). Morphological characteristics were consistent with those of Colletotrichum gloeosporioides species complex (Weir et al. 2012; Park et al. 2018). For molecular identification, we used two representative isolates (HJAUP CH005 and HJAUP CH006) for genomic DNA extraction and amplification, using primers for ITS4/ITS5 (White et al. 1990), Bt2a/Bt2b, GDF1/GDR1, ACT-512F/ACT-783R and CL1C /CL2C (Weir et al. 2012), respectively. The sequenced loci (GenBank accession nos. ITS: OQ625876, OQ625882; TUB2: OQ628072, OQ628073; GAPDH: OQ628076, OQ657985; ACT: OQ628070, OQ628071; CAL: OQ628074, OQ628075) exhibited 98 to 100% homology with corresponding sequences of C. fructicola strains (GenBank accession nos. OQ254737, MK514471, MZ133607, MZ463637, ON457800, respectively). A phylogenetic tree was constructed using the maximum-likelihood method in MEGA7.0 for the sequences of five concatenated genes (ITS-TUB2-GAPDH-ACT-CAL). Our two isolates clustered together with three strains of C. fructicola with 99% bootstrap support values in the bootstrap test (1000 replicates). The isolates were identified as C. fructicola based on morpho-molecular approach. The pathogenicity of HJAUP CH005 was tested indoors by inoculating the wounded leaves of four healthy P. granatum plants. Four leaves from each of two healthy plants were punctured with flamed needles and sprayed with a spore suspension (1 × 106 spores/ml), and four wounded leaves from each of other two plants were inoculated with mycelial plugs (5 × 5 mm3), respectively. Mock inoculations with sterile water and PDA plugs on four leaves each were used as controls. Treated plants were incubated in a greenhouse at high relative humidity, 25°C, and a photoperiod of 12 h. After 4 days, typical anthracnose symptoms similar to natural infection appeared on the inoculated leaves, whereas the control leaves remained asymptomatic. Based on morphological and molecular data, the fungus isolated from the inoculated and symptomatic leaves was identical to the original pathogen, confirming Koch's hypothesis. Anthracnose caused by C. fructicola has been reported to affect numerous plants worldwide, including cotton, coffee, grapes and citrus (Huang et al. 2021; Farr and Rossman 2023). This is the first report of C. fructicola causing anthracnose on P. granatum in China. This disease seriously affects the quality and yield of the fruit and should be of wide concern to us.

First report of Aloe root and stem rot caused by Phytophthora palmivora in Yunnan Province, China

Aloe genus plants are perennial evergreen herb belonging to Liliaceae family which is widely used in food, medicine, beauty, and health care (Kumar et al. 2019). In August 2021, symptoms of root and stem rot was observed in approximately 20% of Aloe vera plantings in Yuanjiang County, Yunnan Province, China (23° 64' 53" N, 101° 99' 84" E). The most typical symptoms were stem and root rot, browning and necrosis of vascular tissues, gradual greening, and reddish-browning of leaves from bottom to top, abscission, and eventual plant death (Fig. S1). Therefore, to isolate and identify the pathogen, the plants showing the above symptoms were collected. The plant tissues were cut from the edges of root and stem lesions, followed by disinfection with 75% ethanol for 1 min, rinsed three times with sterilized distilled water, and cut into 3 × 3 mm small squares after excision of marginal tissues. The tissues were transferred to the oomycetes selective medium (Liu et al. 2022) and incubated at 28 °C in the dark for 3~5 days, and suspected colonies were purified. The colonies were then inoculated onto potato dextrose agar (PDA), V8-juice agar (V8), and oatmeal agar (OA) medium plates for morphological characteristics. Finally, 18 isolates with the same colonial and morphological characteristics were obtained from 30 lesioned tissue and one of them was named as ARP1. On PDA, V8 and OA medium plates, the ARP1 colonies were white. On PDA plate, the mycelia were dense and the colonies were petal-like; on V8 plate, the mycelia were cashmere and the colonies were radial or star-like. Whereas, on OA plate, the mycelia were cotton-like and the colonies were fluffy and radial (Fig. S2 A~C). Mycelium did not have septum with high branching and swelling. Sporangia were abundant, semi-papillate, varying in shape from ovoid-ellipsoid to long-ellipsoid, 18-26 × 45-63 μm (average: 22 × 54 μm, n = 30), sporangia released numerous zoospores from the papillate after maturation. The chlamydospores were spherical, 20-35 μm in diameter (average: 27.5 μm, n = 30) (Fig. S2 D~F). These morphological features were like those of the pathogenic species of the oomycetes (Chen et al. 2022). For the molecular characterization, the genomic DNA of the isolate was extracted using the cetyl trimethyl ammonium bromide method, and the translation elongation factor 1α (tef-1α) (Stielow et al. 2015), β-tubulin (β-tub) (Kroon et al. 2004) and internal transcribed spacer (ITS) (White et al. 1990) of isolated strain ARP1 were amplified using primer pairs EF1-1018F/EF1-1620R, TUBUF2/TUBUR1 and ITS1/ITS4, respectively. The tef-1α, β-tub genes and ITS region of ARP1 were directly sequenced and their sequence information was deposited in GenBank under accession numbers OQ506129, OQ506127 and OQ449628. ARP1 was clustered on the same evolutionary branch with Phytophthora palmivora (Fig. S3). To confirm the pathogenicity of ARP1, the main root of A. vera was wounded to 1 cm long and 2 mm deep with a scalpel blade followed by inoculation with 50 ml suspension of ARP1 zoospores at a concentration of 1 × 106 spores / ml per potted plant, and an equal volume of water as control. All inoculated plants were placed in the greenhouse at 28°C, 12 h / 12 h light / dark. After 15 dpi, the inoculated plants showed typical symptoms of wilted and drooping leaves and stem and root rot, same as observed in the field condition (Fig. S4). After inoculation with ARP1, a strain with the same morphological and molecular characteristics as the original isolate was re-isolated, confirming Koch's postulates. To our knowledge, this is the first report of P. palmivora causing root and stem rot of A. vera in the study region. This disease could be a potential risk for aloe production and therefore appropriate management measures should be taken.

First report of Pseudocerradoa paullula causing aroid leaf rust on Swiss cheese plant Monstera deliciosa in South Carolina, USA

In February 2023, two Monstera deliciosa Liebm. (Araceae) plants with typical symptoms of leaf rust disease were detected at a grocery store in Oconee Co., South Carolina. Symptoms included chlorotic leaf spots and abundant brownish uredinia, mainly on the adaxial surface of more than 50% of leaves. The same disease was detected on 11 out of 481 M. deliciosa plants in a greenhouse at a plant nursery located in York Co., South Carolina, in March 2023. The first plant sample detected in February was used for morphological characterization, molecular identification, and pathogenicity confirmation of the rust fungus. Urediniospores were densely aggregated, globose, golden to golden brown in color, and measured 22.9 to 27.9 µm (aver. 26.0 ± 1.1 µm; n=50) in diameter with wall thickness at 1.3 to 2.6 µm (aver. 1.8 ± 0.3 µm; n=50). Telia were not observed. These morphological traits aligned with those of Pseudocerradoa paullula (basionym: Puccinia paullula; Ebinghaus et al. 2022; Sakamoto et al. 2023; Sydow and Sydow 1913; Urbina et al. 2023). Genomic DNA was extracted from urediniospores collected from the naturally infected plant sample and used for PCR amplification and DNA sequencing of the large subunit (LSU) genetic marker with primers LRust1R and LR3 (Vilgalys and Hester 1990; Beenken et al. 2012). The LSU sequence of the rust fungus in South Carolina (GenBank accession: OQ746460) is 99.9% identical to that of Ps. paullula voucher BPI 893085 (763/764 nt.; KY764151), 99.4% identical to that of voucher PIGH 17154 in Florida, USA (760/765 nt.; OQ275201), and 99% identical to that of voucher TNS-F-82075 in Japan (715/722 nt.; OK509071). Based on its morphological and molecular characteristics, the causal agent was identified as Ps. paullula. This pathogen identification was also corroborated by the U.S. Department of Agriculture, Animal and Plant Health Inspection Service, Plant Pathogen Confirmatory Diagnostics Laboratory in Laurel, Maryland. To confirm the fungus's pathogenicity on M. deliciosa and M. adansonii Schott (Sakamoto et al. 2023), three plants of each Monstera species were inoculated by spraying with a suspension of urediniospores collected from the original plant sample (1 × 106 spores per ml; approx. 40 ml per plant). Three non-inoculated control plants of each host species were treated with deionized water in the same manner. Plants were placed in a plastic tray with wet paper towels to maintain moisture. The tray was placed at 22C for an 8-h photoperiod and covered for five days to facilitate infection. On 25 days after inoculation, abundant spots bearing urediniospores were produced on all leaves of inoculated M. deliciosa plants. A few uredinia were observed on two of the three inoculated M. adansonii plants. All non-inoculated control plants remained asymptomatic. Morphological features of urediniospores collected from inoculated plants matched those of Ps. paullula used as the inoculum. Aroid leaf rust on Monstera plants was officially reported in Australia, China, Japan, Malaysia, Philippines, and Florida, USA (Shaw 1991; Sakamoto et al. 2023; Urbina et al. 2023). This is the first report of Ps. paullula causing this disease on M. deliciosa in South Carolina, USA. Monstera species are popular indoor and landscape plants. Potential impact and regulatory responses regarding Ps. paullula, a newly introduced and rapidly spreading pathogen in the USA, warrant further evaluation and discussion.

First Report of Anthracnose Caused by Colletotrichum siamense on Hydrangea macrophylla in China

Hydrangea macrophylla (Thunb.) Ser. (Hydrangeaceae), a shrubby perennial plant, is widely used as an ornamental flowering plant because of its showy inflorescences and colorful sepals. In October 2022, leaf spot symptom was observed on H. macrophylla in Meiling Scenic Spot, which covers an area of about 143.58 km2 in Nanchang, Jiangxi Province, China (28.78°N, 115.83°E). An investigation was carried out in a 500 m2 mountain area with 60 H. macrophylla plants in a residential garden, the incidence of disease observed was 28~35%. The symptoms were visible as nearly round dark brown spots on the leaves in the early stages of infection. At later stages, the spots gradually developed grayish white center with dark brown margins. To isolate the pathogen, seven leaves randomly selected from 30 infected leaves were cut into 4-mm2 pieces, surface disinfected with 75% ethanol for 30s followed by 5% NaClO for 1 min, rinsed in sterile water three times, placed on potato dextrose agar (PDA), and cultured at 25 °C in the dark for 7 days, and four strains with similar morphological characteristics were obtained from 7 diseased samples. Conidia were aseptate, cylindrical, hyaline, obtuse at both ends, and measured 13.31 to 17.53 × 4.43 to 7.45 µm (15.47 ± 0.83 × 5.91 ± 0.62 µm, n = 60). Morphological characteristics matched Colletotrichum siamense (Weir et al. 2012; Sharma et al. 2013). For molecular identification, two representative isolates (HJAUP CH003 and HJAUP CH004) were used for genomic DNA extraction, and the internal transcribed spacer (ITS), partial sequences of actin (ACT), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), β-tubulin (TUB2) and partial calmodulin (CAL) were amplified, using primer pairs ITS4/ITS5 (White et al. 1990), ACT-512F/ACT-783R, GDF1/GDR1, Bt2a/Bt2b and CL1C/CL2C (Weir et al. 2012), respectively. The sequences were deposited in GenBank (accessions nos. ITS: OQ449415, OQ449416; ACT: OQ455197, OQ455198; GAPDH: OQ455203, OQ455204; TUB2: OQ455199, OQ455200; CAL: OQ455201, OQ455202). Concatenated sequences of the five genes were used to conduct phylogenetic analyses using the maximum-likelihood method in MEGA7.0 (Sudhir et al. 2016) and Bayesian inference analysis in MrBayes 3.2 (Ronquist et al. 2012). Our two isolates cluster together with four strains of C. siamense with 93%ML/1.00BI bootstrap support. The isolates were identified as C. siamense based on the morpho-molecular approach. Pathogenicity of HJAUP CH003 was tested indoors by inoculating detached wounded leaves of six healthy H. macrophylla plants. Three healthy plants with three leaves were punctured with flamed needles and sprayed with a 1 × 106 spores/ml spores suspension, and another three healthy plants were wounded inoculated with mycelial plugs (5 × 5 mm3). Mock inoculations were used as controls with sterile water and PDA plugs on three leaves each. Treated plant tissue were incubated in an artificial climate box at 25°C, 90% relative humidity and a photoperiod of 12 h. After 4 days, symptoms similar to those of natural infection were observed on all wounded inoculated leaves, while no symptoms appeared on mock-inoculated leaves. The fungus isolated from inoculated leaves was identical to the original pathogen based on morphological and molecular data, confirming Koch's hypothesis. It has been reported that C. siamense can cause anthracnose on numerous plants (Rong et al. 2021; Tang et al. 2021; Farr and Rossman 2023). This is the first report of C. siamense causing anthracnose on H. macrophylla in China. The disease is of major concern to the horticultural community as it seriously affects the aesthetic value of ornamentals.

First report of Fusarium equiseti causing bulb rot on lily (Lilium 'White planet' ) in China

Lily (Lilium spp.) is one of the main ornamental plants grown in the world. In addition, bulbs of lily have been extensively used as edible and medicinal herbs in northern and eastern Asia, especially in China (Yu et al. 2015; China Pharmacopoeia Committee 2020; Tang et al. 2021). In August of 2021, a disease of stem and leaf rot was observed on lily cultivar 'White planet' with approximately 25% disease incidence in the greenhouse and fields at the Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences (Beijing, China). The bulbs of symptomatic plants were brown and rotten, with sunken lesions. Symptomatic plants showed short, discolored leaves, and eventually lead to stem wilt and death of the whole plants. Infected bulbs were surface sterilized in 75% ethanol for 30 s, then in 2% sodium hypochlorite for 5 min, and rinsed three times with sterile distilled water. A 0.5×0.5 cm2 tissue piece was then placed on potato dextrose agar (PDA) medium and incubated at 25±1℃. After 5 days, the isolate was purified by single spore isolation technique. The singled-spored fungal colony was characterized by fluffy white aerial mycelia, and produced orange pigments with age. After seven days on Spezieller Nahrstoffarmer agar (SNA), conidia produced from simple lateral phialides. Macroconidia have pronounced dorsiventral curvature typical, significantly enlarged in the middle, a tapered whip-liked pointed apical cell and characteristic foot-shaped basal cell, 3 to 6 septate, measuring 18.71 to 43.01×2.89 to 5.56 μm with an average size of 26.98×3.90 μm (n=30). Microconidia were not observed. Typical verrucose thick chlamydospore with rough walls were profuse in chains or clumps, ellipsoidal to subglobose. These morphological characteristics were consistent with Fusarium spp. (Leslie et al. 2006). For molecular identification, the internal transcribed spacer (ITS), translation elongation factor subunit 1-alpha (TEF1-α) and RNA polymeraseⅡsubunit 2 (RPB2) genes were amplified using primers ITS1/ITS4, EF1/EF2 and 5F2/7cR respectively and sequenced (White et al. 1990; Jiang et al. 2018; O'Donnell et al. 2007). Sequences were submitted to GenBank under accession numbers OM078499 (ITS), Accession OM638086 (TEF1-α) and OM638085 (RPB2). BLAST analysis showed that ITS, TEF1-α and RPB2 sequences shared 100%, 99.8%, 99.2% identity to F. equiseti (OM956073, KY081599, MW364892) in GenBank, respectively. In addition, ITS, TEF1-α and RPB2 sequences shared 100%, 99.53%, 100% identity with Fusarium lacertarum (LC7927, Fusarium incarnatum-equiseti species complex) in the Fusarium-ID database. Based on the morphological characteristics and molecular sequences, the isolates were identified as Fusarium equiseti. A pathogenicity test was performed on potted lily ('White planet') under greenhouse conditions (25±1℃ with a 16 h light and 8 h dark cycle). Three healthy lily bulbs were selected and one bulb was planted in each pot filled with sterilized soil. Each pot was inoculated with 5 mL of conidia suspension (1×107 conidia/mL) in te soil around bulbs with a stem length of 3 cm, with an equal amount of sterilized water as a control. This test had three replicates. After 15 days of inoculation, typical symptoms of bulb rotten, like those observed in the greenhouse and fields, developed on the inoculated plants but not on the controls. The same fungus was consistently reisolated from the diseased plants. To our knowledge, this is the first report that F. equiseti caused bulb rot on Lilium in China. Our result should help with future monitoring and control of lily wilt disease.

First Report of Powdery Mildew Caused by Golovinomyces bolayi on Veronica persica in Central China

Veronica persica, Persian speedwell, is a flowering plant belonging to the family Plantaginaceae. Due to its showy flowers, this plant is widely planted in many home gardens, city parks and universities in China. From April to June 2021, signs and symptoms of powdery mildew were found on leaves of V. persica growing on the campus of Henan Normal University, Henan Province, China. Signs initially appeared as thin white colonies and subsequently white powdery masses were abundant on the adaxial and abaxial surfaces of leaves and covered up to 99 % of the leaf area. The infected leaves showed chlorotic, deformed or senescence features. About 150 V. persica plants were monitored and more than 90 % of the plants showed these signs and symptoms. Conidiophores (n = 20) were 108 to 220 × 10 to 13 μm and composed of foot cells, followed by short cells and conidia. Conidia were hyaline, doliiform-subcylindrical shaped, 21 to 37 × 15 to 22 μm, and showed distinct fibrosin bodies. Conidial germ tubes were produced at the perihilar position. No chasmothecia were observed. The observed morphological characteristics were consistent with those of previously documented Golovinomyces bolayi (Braun and Cook 2012). To further confirm the powdery mildew fungus, structures of the pathogen were harvested and total genomic DNA was isolated using the method previously described by Zhu et al. (2019, 2021). Using the primers ITS1/ITS4, the internal transcribed spacer (ITS) region of rDNA was amplified (White et al. 1990) and the amplicon was sequenced. The resulting sequence was deposited into GenBank under Accession No. MZ343575 and was 100 % identical (592/592 bp) to G. bolayi on Kalanchoe blossfeldiana (LC417096) (Braun et al. 2019). The additional phylogenetic analysis clearly illustrated that the identified fungus and G. bolayi were clustered in the same branch (Zhu et al. 2022a; Zhu et al. 2022b). To test pathogenicity, healthy V. persica plants were collected from the campus of Henan Normal University and leaf surfaces of three plants were inoculated by dusting fungal conidia from mildew-infested leaves using pressurized air. Three plants without inoculation served as a control. The spore-treated and non-treated plants were separately placed in two growth chambers (temperature, 18℃; humidity, 60%; light/dark, 16h/8h). Seven- to eight-days post-inoculation, pathogen signs were noticeable on inoculated plants, whereas control plants remained healthy. Similar results were obtained by conducting the pathogenicity assays twice. Therefore, based on the analysis, G. bolayi was identified and confirmed as the causal agent of the powdery mildew. This pathogen has been reported on V. persica in Iran (Golmohammadi et al. 2019). However, to our best knowledge, there is no report concerning the powdery mildew caused by G. bolayi on V. persica in China. Recently, G. bolayi was segregated from species clades of G. orontii complex (Braun et al. 2019). Our record of the molecular characterization of G. bolayi will support the further phylogeny and taxonomy analysis of the G. orontii complex. The sudden outbreak of powdery mildew caused by G. bolayi on V. persica may detract from plant health and ornamental value. The identification and confirmation of this disease expands the understanding of this causal agent and will offer support for future powdery mildew control.

First report of powdery mildew caused by Erysiphe cruciferarum on spider flower (Tarenaya hassleriana) in China

Spider flower (Tarenaya (Cleome) hassleriana (Chodat) Iltis, Cleomaceae) is an excellent ornamental landscape plant and has an extensive flowering period, and therefore, plays an important role in horticulture (Parma et al. 2022). In May 2020 and April 2021, severe powdery mildew symptoms were observed on spider flower plants in a public garden (22.35°N and 113.56°E) in Shenzhen, China. Approximately 60 % of the plants were infected, and the adaxial surface of diseased leaves were covered with irregular white patches, which developed on tender to old leaves. In severe infections, drying and premature defoliation of infected leaves were observed. Microscopic examinations of mycelia showed irregularly lobed hyphal appressoria. Conidiophores (n = 30) were straight, unbranched, 65.65-92.11 μm long, and consisted of two to three cells. Conidia were formed singly on the top of conidiophores, cylindrical to oblong, 32.15-42.60 × 14.88-18.43 μm (mean 38.26 × 16.89, n = 50), and without distinct fibrosin bodies. Chasmothecia were not observed. The internal transcribed spacer (ITS) region and 28S rDNA was amplified using the primer sets ITS1/ITS5 and NL1/NL4, respectively. The representative sequences of ITS and 28S rDNA (GenBank accession nos.: MW879365 for ITS and MW879435 for 28S rDNA) analyzed by BLASTN search and showed 100 % identity with the sequences from Erysiphe cruciferarum found in GenBank (accession nos.: LC009943 for ITS and MF192846 for 28S rDNA). Phylogenetic analyses were conducted for further confirmation by using the combined sequences of ITS and 28S rDNA and indicated that the isolate ZDH046 grouped in a clade with isolates of E. cruciferarum (Figure S2). Based on morphological and molecular characteristics, this fungus was identified as E. cruciferarum (Braun and Cook, 2012). Koch's postulates were confirmed by gently pressing conidia from diseased leaves onto 30 leaves of healthy spider flower plants. After incubating for 10 d in a greenhouse (25 ℃ and 75 % relative humidity), similar symptoms to the diseased plants appeared on all inoculated leaves, whereas control leaves remained symptomless. Powdery mildew caused by E. cruciferarum on T. hassleriana has so far only been reported from France (Ale-Agha et al. 2008), Germany (Jage et al. 2010), Italy (Garibaldi et al. 2009), and New Zealand (Pennycook 1989, E. polygoni). To our knowledge, this is the first report of E. cruciferarum causing powdery mildew on T. hassleriana in China. This finding expands the known host range of E. cruciferarum in China and indicates a potential threat to plantations of T. hassleriana in China.

First Report of Fusarium asiaticum Causing Sheath Rot of Zizania latifolia in China

Zizania latifolia is perennial plant, belonging to the rice tribe (Oryzeae) of the grass family Poaceae (Xu et al. 2020), which is also called jiaobai in China and commonly consumed as a vegetable crop. In 2022, a sheath rot occurred on Z. latifolia plants in Lishui, the Zhejiang Province of China. Symptoms occurred on the leaf sheath and initially showed as water-soaked chlorotic spots, later enlarging to irregular, elliptic, and elongated dark brown necrotic lesions. Later, lesions fused and extended to most of the leaf sheath leading to wilting. Almost 60% of the surveyed Z. latifolia plants in 100 hectare were affected. Diseased samples were collected for pathogen isolation. Symptomatic tissues were taken from the edge of lesions, sterilized for 10 s in 70% ethanol, then 2 min in 1% NaClO, washed three times with sterile distilled water, and placed on potato dextrose agar (PDA) at 26 °C in the dark. Fungal colonies displaying similar morphology were picked and purified by single spore isolation. In total, 8 isolates were obtained from 8 plant samples. When cultured on PDA, fungal colonies were white, gradually turning pale yellow with time. Macroconidia only were produced on Carnation leaf agar (CLA) and were hyaline, slender, falcate with single foot cells, 3 to 5 septate, and measured 29 to 50 μm × 3.75 to 5.0 μm. Chlamydospores were globose to subglobose and measured 6.8 to 16.5 μm. These morphological features were consistent with the description of Fusarium asiaticum (Leslie and Summerell 2006). For molecular identification, the partial translation elongation factor 1 alpha (TEF1-α) gene and RNA polymerase II second largest subunit (RPB2) gene of three representative isolates were amplified and sequenced (O'Donnell et al. 1998). These sequences were identical to each other, and one representative, Z-3-1, was deposited in GenBank (Accession No. OQ129437 and OQ858619, respectively). Analysis of the TEF1-α and RPB2 sequences of Z-3-1 showed that they were 99.85% (688/689) and 100% (945/945) identical to F. asiaticum strain Daya350-3 (KT380124) and MRC 1976 (MH582121), respectively, in NCBI, and had 99.38% and 100% identity to F. asiaticum strain CBS 110257 (AF212451 and JX171573) in Fusarium-ID. A combined phylogenetic tree based on the TEF1-α and RPB2 sequences showed that Z-3-1 was clustered with F. asiaticum using the neighbor-joining algorithm. Pathogenicity testing was conducted by inoculating potted Z. latifolia plants with a 1×105 conidial suspension of isolate Z-3-1, which was prepared by culturing the fungal strain in PDB at 26°C for 4 days in a shaker incubator. Conidial suspensions (1 mL) were dropped onto sheaths of potted Z. latifolia plants with sterile water serving as controls. All inoculated plants were covered with plastic bags and maintained in a humid growth chamber at 26°C with a photoperiod of 16 h. The inoculation experiment was repeated twice with 5 replicates per test. Four days later, the sheaths of potted inoculated plants displayed symptoms similar to those observed in the field. No symptoms were observed on control plants. Fusarium asiaticum was re-isolated specifically from the symptomatic inoculated Z. latifolia plants and confirmed by morphological and molecular methods, thus fulfilling Koch's postulates. Fusarium asiaticum has been reported to be a pathogen of other plants in China, such as Ligusticum (Zhu et al. 2022) and Setaria italica (Kong et al. 2022). To our knowledge, this is the first report of F. asiaticum causing sheath rot of Z. latifolia in China. The identification of the pathogen is the first step in developing appropriate field management strategies for this new disease.

Detection of Brasiliomyces malachrae Causing Powdery Mildew on Ornamental Cotton (Gossypium hirsutum) plants in Mexico

Cotton (Gossypium L.; Malvaceae) is the most important fiber crop worldwide, also as a source of vegetable protein and edible oil. Cultivated species of cotton were apparently domesticated independently in four separate regions, in both the Old and the New World. Due to its economic importance, it is necessary to study the diseases that limit its production. During July of 2020-2022, symptoms of powdery mildew were observed on 80 ornamental cotton plants in a nursery located in Cuautla (18°52'38"N; 98°58'28"W), Morelos, Mexico. Disease incidence was 29%. Signs first appeared as small white colonies, which subsequently developed into abundant mycelial grown mainly on the upper leaf surface. White patches of mycelia were observed on leaves. In advanced stages of the disease, plants exhibited symptoms of yellowing, necrosis, and early defoliation. Microscopic analysis from 10 plant samples showed that mycelia were amphigenous, epiphyllous, in thin patches and evanescent. Hyphae were hyaline, thin walled and hyphal appressoria were simply lobed. Chasmothecia (n=50) were sub-aggregate, generally spherical to subglobose (46-61 µm in diameter), whitish, subhyaline, smooth, with a peridium of a single cell layer and appendages were absent. Three asci per chasmothecia, subspherical, 30-44 × 26-38 µm, with 4-6 ascospores per ascus. Ascospores were hyaline, ellipsoid to ovoid (16-23 × 10-18 µm). The asexual phase was not observed. The characteristics observed correspond to Brasiliomyces malachrae (Braun and Cook 2012; Cabrera et al. 2018). A voucher specimen was deposited in the Herbarium of the Department of Plant-Insect Interactions at the Biotic Products Development Center of the National Polytechnic Institute under accession no. IPN 10.0114. To confirm identification, DNA was recovered from the fungus and the internal transcribed spacer (ITS) from one sample was amplified by PCR, using the primers ITS1/ITS4 (White et al. 1990). The sequence was deposited in GenBank (OQ546720) and showed 100% sequence homology (647/1642bp) with the type sequence of B. malachrae (LC191217) from Malvastrum coromandelianum in Argentina (Cabrera et al. 2018). Pathogenicity was verified through inoculation by gently dusting conidia from infected leaves onto leaves of five healthy cotton plants. Five noninoculated plants served as controls. All plants were maintained in a greenhouse at temperatures from 28±2°C and relative humidity ranging from 80±5%. The experiment was performed twice. Inoculated plants developed powdery mildew symptoms after 14 days, whereas the control plants remained healthy. The fungus on the inoculated leaves was morphologically identical to that originally observed on diseased plants, thus fulfilling Koch's postulates. To our knowledge, this is the first report of Brasiliomyces malachrae causing powdery mildew on Gossypium hirsutum in Mexico and North America (Farr and Rossman 2023). Powdery mildew on G. hirsutum caused by B. malachrae has been previously identified in Venezuela by Hanlin and Tortolero (1984). This disease could be a primary source of inoculum of powdery mildew for commercial cotton plantations, derived from the free movement of ornamental plants.

First report of Robbsia andropogonis causing bacterial leaf spot of bougainvilleas in Taiwan

Bougainvilleas (Bougainvillea spp.) are popular ornamentals commonly grown as bushes, vines, or trees worldwide (Kobayashi et al. 2007). Leaf spot symptoms were observed on a bougainvillea hedge located in North District, Taichung, Taiwan during August of 2022. The lesions were brown, necrotic and had yellow halos (Fig. S1). All the plants at the location showed similar symptoms. Leaf samples were collected from five plants and symptomatic tissues were minced in 10 mM MgCl₂. The samples were streaked onto nutrient agar (NA) and after culturing at 28°C for 2 days, small, round, creamy white colonies were consistently isolated from all the samples. A total of five strains (BA1 to BA5) were obtained; each of them was isolated from a different plant. All five strains induced hypersensitive response in tobacco leaves. Amplification and sequencing of the isolated strains' 16S rDNA using primers 27F and 1492R (Lane 1991) revealed that all five strains shared identical sequences (GenBank accession no. OQ053015) with Robbsia andropogonis LMG 2129^T (formerly Burkholderia andropogonis and Pseudomonas andropogonis; GenBank accession no. NR104960; 1,393/1,393 bp). Further testing of BA1 to BA5's DNA samples using the pathogen's species-specific primers Pf (5'-AAGTCGAACGGTAACAGGGA-3') and Pr (5'-AAAGGATATTAGCCCTCGCC-3'; Bagsic et al. 1995) successfully amplified the expected 410-bp amplicon in all five samples; the sequences of the PCR products completely matched to those of BA1 to BA5's 16S rDNA. Strains BA1 to BA5 also tested negative for arginine dihydrolase and oxidase activity, and failed to grow at 40°C, all of which are consistent with descriptions of R. andropogonis (Schaad et al. 2001). Pathogenicity of the isolated bacteria was confirmed by spray inoculation. Three representative strains, BA1 to BA3, were used for the assay. Bacterial colonies were scraped from NA plates and suspended in 10 mM MgCl₂ added with 0.02% Silwet L-77. The concentrations of the suspensions were adjusted to 4.4-5.8 x 10⁸ cfu/ml. The suspensions were sprayed onto three-month-old, cutting-propagated bougainvillea plants (to runoff). Controls were treated with bacteria-free solutions. Three plants were used for each treatment group (and the controls). The plants were placed in a growth chamber (27/25°C, day/night; 14-hour photoperiod) and bagged for three days. Within 20 days post inoculation, brown, necrotic lesions resembling those observed in the sampling site were observed on all inoculated plants, but not on the controls. One strain was re-isolated for each treatment group and the re-isolated strains all shared the same colony morphology and 16S rDNA sequence with BA1 to BA5. Additional PCR testing of these re-isolated strains using Pf and Pr also produced the expected amplicon. This is the first formal report of R. andropogonis affecting bougainvilleas in Taiwan. The pathogen has been reported causing diseases of betel palm (Areca catechu), corn and sorghum in Taiwan (Hseu et al. 2007; Hsu et al. 1991), some of which are economically important (Lisowicz 2000; Navi et al. 2002). As such, infected bougainvilleas could potentially serve as an inoculum source for these diseases.

First report of Dickeya dadantii causing bacterial soft rot of Scindapsus pictus in Taiwan

Scindapsus pictus (satin pothos or silver vine) is an evergreen climbing plant belonging to the Araceae family, subfamily Monstereae (Bown, 2000), which is also cultivated as a foliage ornamental (Masnira et al. 2019). In September of 2022, soft rot symptoms were observed on potted S. pictus plants grown in a greenhouse in Nantun District, Taichung, Taiwan, in which soft rot of another aroid (philodendron) has also been reported (Wu et al. 2023). The symptoms appeared on the petioles and most of them tended to extend to the leaf blades; the colors of leaf lesions ranged from dark brown to gray (Fig. S1). Some 70% of the plants in the greenhouse showed similar symptoms and losses were estimated to be 15-30%. Four symptomatic plants were sampled. Macerated tissues from rotting petioles were soaked in 10 mM MgCl₂ and observed under a light microscope (Nikon, Japan) at 400 x magnification. Motile, rod-shaped bacteria were observed, and 1-2 loopfuls of undiluted sample suspension were streaked onto nutrient agar (NA; Gibco, USA). After culturing at 28°C for 1 day, all samples yielded round, creamy-white colonies (0.9 mm in diameter) and from each of the four samples a pure culture was obtained (Spi1-Spi4). All isolates exhibited oxidative and fermentative metabolism of glucose (Schaad et al. 2001). They caused pitting on crystal violet pectate agar, induced maceration on potato tuber and were tested positive for phosphatase activity and indigoidine production (Lee and Yu 2006; Schaad et al. 2001). Polymerase chain reaction tests using Dickeya-specific primers 5A and 5B (Chao et al. 2006) amplified the expected amplicon (0.5 kb) in extracted DNA samples of all isolates. Identification of the strains was achieved by amplifying and sequencing fragments of the housekeeping genes gyrB, recN, dnaA, dnaJ, and dnaX (Marrero et al. 2013); the lengths of the five gene fragments analyzed were 822, 762, 720, 672, and 450 bp, respectively (accession nos. OP985528-OP985532). The five sequences were concatenated for every isolate; the resulting 3,426 bp sequences were aligned with ClustalW and found to be identical. A maximum-likelihood analysis was conducted using the 3,426-bp sequences and those of known Dickeya species' type strains. Spi1 to Spi4 clustered with D. dadantii subsp. dieffenbachiae NCPPB 2976^T and D. dadantii subsp. dadantii CFBP 1269^T (Fig. S2) with sequence identities of 98.4 and 98%, respectively. To fulfil Koch's Postulates, stab inoculations of the four isolates into the petioles of cutting propagated, 38-day-old S. pictus plants (3 plants per isolate) were conducted using sterile toothpicks. The amounts of bacteria used was approximately 10⁶ cfu per toothpick; the bacterial loads were estimated by suspending the cells in 10 mM MgCl₂ and spread-plating diluted suspensions on NA. Sterile toothpicks were used as control. All tested plants were sealed in plastic bags (containing wet paper towel) and kept in a growth chamber (28°C; 12-h photoperiod). After 1 day, all isolates induced soft rot symptoms resembling those observed under natural conditions in the greenhouse. Bacteria were re-isolated, and they all shared the same dnaX sequence with strains Spi1 to Spi4. This is the first report of S. pictus affected by D. dadantii in Taiwan. Further investigation is needed to determine whether Spi1-Spi4 belong to D. dadantii subsp. dieffenbachiae. Dickeya dadantii has been found infecting different aroids (Lee and Chen 2021; Lin et al. 2012). The species has also been reported in Taiwan on poinsettia (Wei et al., 2019) and philodendron (Wu et al. 2023). Because these plants are often grown closely in the same facilities, growers should be wary of D. dadantii's spread among these plants. Reduction of environmental humidity and avoiding overhead irrigation may be effective in preventing the pathogen's transmission.

First Report of Puccinia lagenophorae on Senecio vulgaris in Pennsylvania

Common groundsel (Senecio vulgaris L.), is an aster native to Eurasia and is now a common weed in gardens, roadsides and vacant lots worldwide. In 2001, Scholler and Toike were first to report that common groundsel was a host for the rust fungus Puccinia lagenophorae Cooke in North America (Scholler and Toike 2001). This report from California was followed by reports of P. lagenophorae infections on common groundsel in New York, Oklahoma, and Oregon (Little-field et al. 2005). In 2007, Bruckart et al. published the first report of this host-pathogen combi-nation in Canada (Bruckart et al. 2007). To our knowledge, there are no published reports of P. lagenophorae on common groundsel in Pennsylvania (Farr and Rossman 2022). In May 2022, symptomatic common groundsel plants were observed in Biglerville, Adams Co., southern Penn-sylvania (N 39.9268047, E 77.2473878). Host plants exhibited conspicuous aecia on deformed stems (Fig. 1). Disease symptomology and morphology were consistent with P. langenophorae (Scholler and Toike 2001). P. lagenophorae is an autoecious rust that forms aecia and telia, but only aecia are typically formed on Senecio spp.; telia were not noted during our observations. Aecia were orange, cup-shaped, bordered by fragmented recurved peridia (Fig. 1), and they had mean diameters 262.9 ± 20.9 X 175.2 ± 22.2 μm (n = 20). Aeciospores were orange, oval, with mean diameters of 16.5 ± 0.97 X 11.5 ± 1.08 μm (n = 20). Fungal DNA was extracted from symptomatic stems. Polymerase chain reaction and sequencing of the 28S region of the nuclear ribosomal DNA repeat were conducted with primers Rust2inv and LR6 following protocols in Aime (2006). The sequence shared 100% identity (909 / 909 bp) with 8 sequences of P. la-genphorae in GenBank, including one on Ozothamnus cordatus from Perth, Western Australia, Australia (KF690699), vouchered in the Queensland Plant Pathology Herbarium (BRIP 57770), Brisbane, Queensland, Australia. A voucher specimen has been preserved in the Arthur Fungari-um at Purdue University (PUR N24039) with corresponding 28S sequence (GenBank accession OP718536).

First report of 'Candidatus Phytoplasma asteris' associated with cyclamen little leaf in Hungary

Cyclamen (Cyclamen persicum) is a small perennial flowering plant with fragrant, showy flowers on long stems rising above the foliage. Between 2018 and 2022, about 6% of C. persicum plants belonging to diverse varieties showed stunting, leaf yellowing, virescence and phyllody in commercial nurseries at three locations (Tiszabög, Szombathely and Kecskemét) in Hungary. These symptoms are similar to those associated with the phytoplasma disease described in Italy known as cyclamen little leaf (Bertaccini, 1990) were observed in plants of six cyclamen cultivars: in 21 out of 352 plants of Super Serie Mini Winter 'Mix', 19 out of 286 plants of Super Serie Micro 'Mix', 12 out of 199 plants of Halios 'Mix', 3 out of 17 plants of Fantasia 'Purple', 1 out of 7 plants of Curly 'Early Mix Evolution' and 4 out of 66 plants of Halios Curly 'Rose' plants. Total DNA was extracted from petioles collected when possible from 10 symptomatic and 5 symptomless plants from each cultivar by a CTAB method (Ahrens and Seemüller 1992) and used as templates for PCR. Phytoplasma 16S rDNA was amplified using universal primers P1/P7 and R16F2n/R16R2 (Lee et al. 1998 and references therein). Translocase protein (secY) gene was amplified with AYsecY_F-46 (5'-AAGCAGCCATTTTAGCAGTTG-3') and AYsecY_R1450 (5'-AAGTAATCAGCTATCATTTGGTTAGT-3') primer pair, which was designed on the basis of aster yellows (AY) phytoplasma secY sequences available in Genbank. Elongation factor Tu (tuf) was amplified with fTuf1/rTuf1 (Schneider et al. 1997a) primer pairs. Thermocycler conditions consisted of 98°C for 2 min, 32 cycles at 98°C for 30 s, 60°C or 55°C (in case of tuf) for 30 s and 72°C for 1 min, followed by a final extension of 72°C for 10 min with Phusion High-Fidelity DNA Polymerase (New England Biolabs, Ipswich, MA, USA). Amplicons of the expected sizes (P1/P7: 1.8 kb, R16F2n/R16R2: 1.1 kb, AYsecY_F-46/AYsecY_R1450: 1.5 kb, fTuf1/rTuf1: 1.1 kb) were produced from all symptomatic plants but not from the asymptomatic ones. Amplified PCR products were gel purified and ligated into the pJET1.2/blunt cloning vector using a CloneJET PCR cloning kit (Thermo Fisher Scientific, Waltham, MA). The cloned PCR fragments (at least three from each PCR reaction) were sequenced from both directions by LGC Genomics (Berlin, Germany) using pJET1.2 forward and reverse primers, and the obtained sequence was deposited in GenBank. The 16S rRNA gene sequences (GenBank Accession Nos. ON594635 and ON594636) showed 100% and 99.95% identity, respectively, with Onion yellows phytoplasma strain OY-M (GenBank AP006628) from the 'Candidatus Phytoplasma asteris' 16SrI-B subgroup. . In iPhyClassifier analysis, the virtual RFLP pattern of 16S rDNA was identical (similarity coefficient 1.00) to the reference pattern of 16Sr group I, subgroup B (GenBank AP006628). This is in agreement with the results of Schneider et al. (1997b) and Seemüller et al. (1998) in Germany, where phytoplasmas associated with a cyclamen disease were enclosed in the 16SrI-B subgroup. Other researches in Italy (Alma et al., 2000) and Israel (Weintraub et al., 2007) revealed that phytoplasmas belonging to the 16SrI-C and 16SrXII-A groups have been associated with cyclamen diseases. The obtained secY and tuf gene fragments (GenBank ON564432 and ON515746) shared 99.3% and 99.9% sequence identity, respectively, with Onion yellows phytoplasma strain OY-M. To our knowledge this is the first identification of 'Candidatus Phytoplasma asteris' in cyclamen in Hungary.

First Report of Corynespora cassiicola Causing Leaf Spot on Jasminum nudiflorum in China

Winter jasmine (Jasminum nudiflorum Lindl.), a trailing, deciduous shrub, is widely used as an ornamental plant. Its flowers and leaves also has great medicinal value for treatment of inflammatory swelling, purulent eruptions, bruises and traumatic bleeding (Takenaka et al. 2002). In October 2022, leaf spot symptoms were observed on J. nudiflorum distributed in Meiling Scenic Spot (28.78°N, 115.83°E) and Jiangxi Agricultural University (28.75°N, 115.83°E), Nanchang, Jiangxi Province, China. In a week-long series of investigations, the incidences of disease could range up to 25%. Initially, the symptoms of the lesions were small yellow circular spots (0.5 to 1.8 mm), and gradually developing irregular spots (2.8 to 4.0 mm) with grayish white central parts, a dark brown inner ring, and outer yellow halo. To identify the pathogen, sixty symptomatic leaves from fifteen different plants were collected, of which twelve were randomly selected, cut into 4-mm2 pieces, and surface sterilized with 75% ethanol for 30s followed by 5% NaClO for 1 min, rinsed four times with sterile water, and then placed on potato dextrose agar (PDA) medium at 25 °C in the dark for 5 to 7 days. Six isolates with similar morphological characteristics were obtained. Aerial mycelium was vigorous, downy and exhibited white to grayish-green coloration. Conidia were solitary or catenate, pale brown, obclavate to cylindrical, apex obtuse, one to 11 pseudosepta, 24.9 to 125.7 × 7.9 to 12.9 μm (n = 50). Morphological characteristics matched Corynespora cassiicola (Ellis 1971). For molecular identification, two representative isolates (HJAUP C001 and HJAUP C002) were selected for genomic DNA extraction, and the ITS, TUB2 and TEF1-α gene were amplified, using the primer ITS4/ITS5 (White et al. 1990), Bt2a/Bt2b (Lousie and Donaldson 1995) and EF1-728F/EF-986R (Carbone and Kohn 1999), respectively. The sequenced loci (GenBank accession nos. ITS: OP957070, OP957065; TUB2: OP981639, OP981640; TEF1-α: OP981637, OP981638) of the isolates were 100, 99 and 98% similar to the corresponding sequences of C. cassiicola strains (GenBank accession nos. OP593304, MW961419, MW961421, respectively). Phylogenetic analyses of combined ITS and TEF1-α sequences was performed using maximum-likelihood method in MEGA 7.0 (Kuma et al. 2016). The result showed that our isolates (HJAUP C001 and HJAUP C002) clustered with four strains of C. cassiicola at 99% bootstrap values in the bootstrap test (1000 replicates). Based on the morpho-molecular approach, the isolates were identified as C. cassiicola. The pathogenicity of one representative strain (HJAUP C001) was tested by inoculating the wounded leaves of six healthy J. nudiflorum plants under natural condition. Three leaves from each of three plants were punctured with flamed needles and sprayed with a conidial suspension (1 × 106 conidia/ml), and three wounded leaves from each of other three plants were inoculated with mycelial plugs (5 × 5 mm3). Mock inoculations were used as controls with sterile water and PDA plugs on three leaves each, respectively. Leaves from all treatments were incubated in a greenhouse at high relative humidity, 25°C, and 12-hour photoperiod. After one week, all wounded inoculated leaves appeared similar symptoms as described above, whereas the mock inoculated leaves were still healthy. Similar isolates with grayish white and vigorous aerial mycelium were reisolated from inoculated and symptomatic leaves and identified as C. cassiicola by DNA sequencing, fulfilling Koch's postulates. It has been reported that C. cassiicola can cause leaf spots on numerous plant species (Tsai et al. 2015; Lu et al. 2019; Farr and Crossman 2023). However, to our knowledge, this is the first report of C. cassiicola causing leaf spots on J. nudiflorum in China. This finding aids in protection of J. nudiflorum, a medicinal and ornamental plant with high economic value.

Detection of aroid leaf rust Pseudocerradoa paullula on Swiss cheese plant Monstera deliciosa in the continental USA

Monstera deliciosa Liebm. (Araceae, Monocots), sometimes referred to as Swiss cheese plant, is one of the most common aroids used as an indoor and landscape ornamental plant (Cedeño et al. 2020). Production of M. deliciosa and other closely related Araceae species represents an important sector of the ornamental nursery business worldwide. Swiss cheese plant is believed to have originated in the tropical forests of southern Mexico, where its fruit is considered a delicacy due to its sweet, exotic flavor (Cedeño et al. 2020). Since 2019, symptomatic Monstera plants from two plant nurseries and residential properties in South Florida were submitted for disease diagnosis to the Florida Department of Agriculture and Consumer Services, Division of Plant Industry (FDACS-DPI) in Gainesville, Florida, and to the University of Florida, Tropical Research and Education Center Plant Clinic in Homestead, Florida. Symptoms included small chlorotic spots on the leaf surface, which expanded and became brown to reddish-brown often with a yellow halo and produced uredinia with abundant urediniospores. The pathogen was identified morphologically as the rust fungus Pseudocerradoa (=Puccinia) paullula (Syd. & P. Syd.) M. Ebinghaus & Dianese (Pucciniaceae, Basidiomycota) (Ebinghaus et al. 2022), characterized by the production of pseudosuprastomatal uredinia. Uredinospores light-brown and globose, echinulate (1 µm height), reddish to light brown, 24 - 31 µm diameter, with thick walls, 1.5 - 2.5 µm height (n=15). Teliospores 2-celled, light-yellow and ellipsoidal, 23 - 28 × 19 - 24 µm (n =15) were observed in sori appearing as dark-brown leaf spots on the adaxial side of the leaves (e-Xtra Fig. 1). Molecular characterization of the fungal pathogen was based on the small subunit (SSU), internal transcribed spacer (ITS), and large subunit (LSU) of the ribosomal RNA genes (Aime 2006) with the addition of a LSU internal primer specific for the rust species Ppaullula_int-forward 5'ATAGTTATTGGCTTTGATTTACA-3' designed in this study to increase the quality and the sequence read length due to a 3'- ~21-Ts-homopolymer (e-Xtra Fig. 2) (GenBank accession number ON887196, ON887197, OQ275200, OQ275201). In addition to morphological identification, the host plant was identified using the Ribulose-1,5-bisphosphate carboxylase-oxygenase (rbcL) and Maturase K (matK) genes (Fazekas et al. 2012) (GenBank accession numbers ON887189, ON887193, respectively). MegaBlast searches confirmed the morphological identification with 100% identity to M. deliciosa vouchers GQ436772 and MK206496, respectively (Chen et al. 2015). Dried specimens were deposited in the Plant Industry Herbarium Gainesville (PIHG 16226, 16227, 17154, 17155). Molecular identification of the rust pathogen P. paullula was carried out through megaBlast (Chen et al. 2015) searches together with a phylogenetic analysis performed in RAxML v8 (Stamatakis 2014) (e-Xtra Fig. 3). Koch's postulates were performed by using urediniospores, collected from an infected sample and were kept for 7 days at 4 C, as an inoculum source. Healthy rooted M. deliciosa plants were inoculated by rubbing the inoculum on both leaf surfaces at >90% RH, room temperature, 12/12 light cycle. After the incubation period (48 h), plants were placed in a climate-controlled greenhouse and watered twice a week, ~30 C, ~65 RH, 12/12 light cycle. After three weeks, all inoculated plants developed symptoms resembling those observed on the samples submitted for disease diagnosis. Controls did not show symptoms. Spores from the pustules of inoculated plants were identified as P. paullula by both morphology and molecular means. The genus Pseudocerradoa comprises P. paullula and its sister species P. rhaphidophorae (Syd.) M. Ebinghaus & Dianese. Both species can be distinguished by size and coloration of urediniospores and their host range within the Araceae. Pseudocerradoa rhaphidophorae produces smaller urediniospores and only occurs on Rhaphidophora species (Shaw 1995). Pseudocerradoa paullula is not considered fully established in Florida, since the host distribution is mainly restricted to indoors and M. deliciosa is rarely used as an outdoor ornamental (Wunderlin et al. 2023). Here we name the disease caused by P. paullula as "aroid leaf rust", due to its ability to infect several species in this plant family. Other closely related hosts reported as susceptible to this pathogen are Monstera standleyana G.S.Bunting (as M.s. cv. variegata), Monstera adansonii var. laniata (Schott) Mayo & I.M. Andrade, Monstera subpinnata (Schott) Engl., Typhonodorum lindleyanum Schott, and Stenospermation sp. (Shaw 1991, 1992, 1995). To date, the aroid leaf rust was only known from Australia, China, Japan, Malaysia, and Philippines (Lee et al. 2012; Shaw 1991). Based on our review, P. paullulla was intercepted once from Malaysia in 2014 at the port of Los Angeles, USA (BPI voucher 893085). This present study reports the establishment of P. paullula in Florida, USA infecting M. deliciosa.

First report of constricta yellow dwarf virus infecting Lobelia in the United States and the world

Blue cardinal (Lobelia siphilitica L., family: Campanulaceae) is a popular perennial ornamental plant. Lobelia spp. have been reported as hosts of economically important viruses including cucumber mosaic virus (Nameth and Fisher, 2001), turnip mosaic virus (Lockhart et al., 2002), and tomato spotted wilt virus (Brown, 1988). During fall 2022, in a garden in Fayetteville, Arkansas, USA, yellow speckling, chlorosis, and dwarfing were observed on several cardinal plants. Three symptomatic plants were sampled, and RNA was isolated as described in Poudel et al. (2013) and pooled. Material was sequenced using the MinION platform as described by Liefting et al. (2021). A total of 56,700 raw reads (mean-length 326) were analyzed using VirFind (Ho and Tzanetakis, 2014) revealing 23 contigs ranging from 209-12,776 nucleotides (nt) which showed 96.2-98.4% identity with constricta yellow dwarf virus (CYDV; genus Alphanucleorhabdovirus, KY549567) and 16 contigs ranging from 201-531 nt with 83.4-95.7% identity with hydrangea chlorotic mottle virus (HdCMV; genus Carlavirus, EU754720). A total of 6,387 reads were mapped to the CYDV genome (KY549567) with 181x average coverage per nucleotide, and the consensus sequence of 12773 nt shared 98.1% identity to KY549567. The results were verified by RT-PCR and sequencing of the amplicons using primers 8825F: 5'-ACCCTGAGACAGGCATTGTG-3' and L2 9760: 5'-GCCGTACTATGAGAAGGGGC-3' for CYDV and 6495F: 5'-CAAGTACGTCTGTGTGAGGT-3' and 6630R 5'-CTTTTTGATAGTGTCATTGCTACC-3' for HdCMV. RNA was subsequently extracted from eight symptomatic and 12 symptomless samples. All symptomatic samples tested positive for CYDV but none of the 20 was positive for HdCMV indicating that CYDV is possibly the causal agent of the observed symptoms. Amplicons were CYDV specific and showed 91-98% nt identity (99-100% amino acid identity) (accession No. OP998261-63) with the CYDV isolate from Solanum tuberosum (KY549567). To the best of our knowledge, this is the first report of CYDV infecting L. cardinalis in the USA and the world. CYDV has been reported as an important pathogen of potato in the USA and recent reports indicate that emergence and re-emergence of rhabdoviruses on new hosts worldwide may threaten agricultural production (Bejerman et. al., 2021). Given the lack of monitoring of cardinal plants for viruses, this could serve as a reservoir of CYDV for several vegetables and ornamental crops (Jang et al., 2017).

First Report of Neofusicoccum mediterraneum and Neofusicoccum parvum Causing Pine Ghost Canker on Pinus spp. in Southern California

Pinus eldarica, P. halepensis and P. radiata are important conifer species native to Mediterranean regions that are cultivated in the southwestern United States for landscaping (Phillips and Gladfelter, 1991; Chambel et al., 2013). Among them, Monterey pine (P. radiata) is native to restricted areas of California and Mexico, but it is extensively grown for timber production in other countries, especially in the Southern Hemisphere (Rogers, 2004). From 2018 to 2022, severe dieback and cankers have been detected on more than 30 mature pines of the three species within a 40-ha urban forest in Orange County, Southern California. Symptoms initiate on the lower portion of the canopy and advance into the crown, leading to quick dieback and, in some cases, to tree death. Cross sections of affected branches revealed wedged cankers with irregular, indistinct margins, and cryptic discoloration (i.e., "ghost cankers"). Pycnidia were observed on the surface of each bark scale of branches with advanced infections. Two morphotypes of Botryosphaeriaceae colonies (n = 34 isolates) were recovered consistently from more than 90% of the symptomatic pines. Two isolates per morphotype were grown on pistachio leaf agar (Chen et al., 2014) for 14 days to induce pycnidia formation. Conidia (n = 50) were hyaline, thin-walled and fusoid to ellipsoidal in shape, ranging from 16.1 to 27.9 (22.6) × 5.4 to 8.2 (6.8) µm for the first morphotype and 11.5 to 20.4 (16.3) × 4.8 to 8.6 (6.3) µm for the second morphotype. The rDNA internal transcribed spacer (ITS), beta-tubulin (tub2), and translation elongation factor 1-alpha (tef1-α) partial gene regions were amplified and sequenced using the primers ITS5/ITS4 (White et al., 1990), Bt2a/Bt2b (Glass and Donaldson, 1995), and EF1-728F/EF1-986R (Carbone and Kohn, 1999), respectively. A multi-locus phylogenetic analysis revealed that isolates UCD9433 and UCD10439 clustered with the ex-type strain of Neofusicoccum mediterraneum (CBS:113083), and isolates UCD9161 and UCD9434 grouped with N. parvum (CMW:9081). Sequences were submitted to GenBank (nos. OP535391 to OP535394 for ITS, OP561946 to OP561949 for tef1-α, and OP561950 to OP561953 for tub2). Pathogenicity tests were performed with above-mentioned isolates on 20-mm-diameter healthy branches of mature Monterey pines (n = 10, 14 years old) located in a research field at UC Davis. Isolates were grown for 7 days on potato dextrose agar and inoculated in the internode area by removing a 5-mm-diameter disk of the bark with a sterile cork borer and placing a 5-mm-diameter mycelial plug. Controls were mock-inoculated with sterile agar plugs, and the experiment was performed twice. After three months, inoculations resulted in vascular lesions that ranged from 20.6 to 49.7 (32.7) mm with N. mediterraneum and from 13.5 to 71.0 (33.6) mm with N. parvum, and the same pathogens were reisolated (70 to 100% recovery). Controls remained symptomless and no botryosphaeriaceous colonies were recovered. Both N. mediterraneum and N. parvum are polyphagous pathogens associated with multiple woody plant hosts (Phillips et al., 2013). Previously, only N. parvum has been associated with pine cankers in Iran, however, the pine species was not indicated (Abdollahzadeh et al., 2013). The detection of these pathogens in urban forests raises concerns of potential spillover events to other forest and agricultural hosts in Southern California. To our knowledge, this is the first report of N. mediterraneum and N. parvum causing Pine Ghost Canker on P. eldarica, P. halepensis and P. radiata.

First report of Tomato spotted wilt orthotospovirus infecting agapanthus (Agapanthus praecox) in South Africa

Agapanthus praecox Willd. is an ornamental flowering plant that is indigenous to southern Africa and was reported to be a host of tomato spotted wilt orthotospovirus (TSWV) in Australia in 2000 (Wilson et al. 2000). Tomato spotted wilt orthotospovirus (TSWV) belonging to the genus Orthotospovirus of the family Tospoviridae is a single-stranded negative sense RNA virus known to cause disease symptoms in many crops and ornamental plant species. This virus is in the top 10 of most economically important plant viruses worldwide (Rybicki 2015; Scholthof et al. 2011). In May 2021, leaf material from three agapanthus (Agapanthus praecox) plants displaying chlorotic mottling, and yellow lesions (Supplementary material 1A) was collected in Mbombela, South Africa. One gram of symptomatic leaf material was used for total RNA extraction from each of the three samples using a CTAB extraction protocol (Ruiz-García et al. 2019). The three RNA extracts were pooled, and a sequencing library was constructed using the Ion Total RNA-Seq Kit v2.0 and RiboMinus™ Plant Kit for RNA-Seq (ThermoFisher Scientific) (Central Analytical Facility (CAF), Stellenbosch University). The RNA library was sequenced on an Ion Torrent Proton Instrument (CAF). A total of 34,392,939 single-end reads were obtained. Data was trimmed for quality with Trimmomatic (CROP:250, MINLEN:50). De novo assembly was performed on the remaining 32,281,645 trimmed reads (average readlength: 100 nt, range: 50-250 nt) using SPAdes 3.13.0 and resulted in 4,788 contigs. BLASTn analysis identified viral contigs longer than 1,000 nucleotides (nts) with high nucleotide (nt) identity to TSWV (6 contigs), as well as to the newly discovered viruses, agapanthus tungro virus (AgTV) (1 contig), and agapanthus velarivirus (AgVV) (4 contigs) (Read et al 2021). Read mapping was performed against the relevant reference sequence with the highest nt identity to the contigs. For TSWV, 4995, 21221 and 14574 reads mapped to segment L (KY250488), M (KY250489) and S (KY250490) of isolate LK-1, respectively resulting in 99.97%, 100.00% and 99.97% genome coverage of the reference accessions. The nt identity between the reference accessions and the consensus sequences generated (OP921761-OP921763) were 97.26%, 97.64% and 97.82% for segment L, M and S. The presence of TSWV was confirmed in the HTS sample using an RT-PCR assay (primers L1 and L2) targeting the L segment of TSWV (Mumford et al. 1994). In July 2022, additional leaf samples displaying symptoms of chlorotic mottling, streaking, and ringspots were collected from 31 symptomatic and 3 asymptomatic agapanthus plants in public gardens in Stellenbosch, South Africa. Using the above-mentioned RT-PCR assay, 13 of the symptomatic samples tested positive for TSWV. All six plants displaying ring spot symptoms (Supplementary material 1B) were infected with TSWV. However, plants that displayed yellow streaking (five samples) and chlorotic mottling (two samples) (Supplementary material 1C-D) were also positive for TSWV which could be due to the presence of other viruses, plant growth stage, infection time or just variable symptom expression in a single host species as reported previously (Sherwood et al. 2003). The 275 bp RT-PCR amplicons of the HTS sample and three additional positive samples were validated with bidirectional Sanger sequencing (CAF) and had 96% identity to accession KY250488. The pairwise nt identity between amplicons was 98.55-100%. This is the first report of TSWV infecting agapanthus in South Africa. This study contributes information towards the distribution and incidence of TSWV and highlights the need for nurseries to screen plant material before propagation.

First report of a rust fungus (Puccinia sp.) infecting lemongrass in Minnesota

In July 2021 and July - Oct. 2022, in a community garden near Mankato, Minnesota, rust disease was observed on lemongrass (Cymbopogon citriatus). In 2022, all 20 plants in the garden plot were infected. Lemongrass is used in some Asian cuisines and for tea or medicine. It is not hardy in Minnesota but is grown in gardens and outdoors in small-scale production. Uredinia were cinnamon-brown on the abaxial surface of leaf blades. Pustules were small (0.2 - 0.5 x .01 - .05 mm) and numerous, causing large necrotic lesions and leaf dieback (Fig. 1A). Severity ranged from 5 - 50% leaf loss. Urediniospores were finely echinulate, slightly ovular (22-25 x 20-23 μm), thick-walled (2.5-4 μm), with 3-4 roughly equatorial, sometimes scattered germ pores (Fig 1B; 1C). Clavate paraphyses were abundant. Other spore types were not observed. The pycnidia of a mycoparasitic fungus were present within the uredinia. The specimen was submitted to the Arthur Fungarium at Purdue University (PUR N24011). Primers ITS1rustF10d (Barnes and Szabo, 2007) and ITSRu1 (Rioux et al., 2015) were used to generate amplicons for the rust fungus, and ITS4 and ITSF+ (White, 1990) for the mycoparasite. Amplicons were sequenced on an Oxford Nanopore MinIon with R9 flow cells following manufacturer instructions. Reads (PRJNA802078) were filtered for quality (> Q13) and length (> 200 bp), mapped to reference sequences, aligned, and separated based on similarity. Consensus sequences were generated for the amplicons of the rust fungus and of two other fungi. BLASTn searches of the ITS sequences, OM442990 and OM442991, identified an Alternaria sp. (99.8% match (597/598) with MT548677) and Sphaerellopsis filum (syn. Darluca filum; 98.3% (529/538 bp) match with EF600974), a common rust mycoparasite. A BLASTn search of the rust fungal ITS sequence (OM442989) yielded 98.9% (549/555) and 98.6% (633/642) match with MT955206 and MT955207, respectively, both Puccinia cesatii on Bothriochloa ischaemum. The third closest match is P. cymbopogonis on C. citriatus (97.1% (595/613) with KY764115). Urediniospore morphology is consistent with that of P. cesatii (Cummins, 1971). Available evidence suggests the fungus is P. cesatii or a closely related species. Puccinia cesatii has been reported infecting Cymbopogon spp. (Stevenson et al., 1926; Dhar and Rekha, 1984), but lemongrass is not generally considered a host-possibly due to confusion of P. cesatii with P. cymbopogonis, a closely related rust pathogen of lemongrass that is morphologically very similar to P. cesatii. P. cymbopogonis has not been reported in the U.S. Rust diseases of lemongrass have been reported in three states: Hawaii (Gardner, 1985), California (Koike and Molinar, 1999), and Florida (Ploetz et al., 2014). In each case, the rust was identified as Puccinia nakanishikii. Urediniospores of P. nakanishikii are larger (26-36 μm long) (Cummins, 1971) and the ITS2 has no significant sequence similarity. P. cesatii is widespread in Eurasia, the southwest U.S., and Mexico (Cummins, 1971). Cummins lists three genera closely related to Cymbopogon as telial hosts of P. cesatii: Bothriochloa, Capillipedium, and Dicanthium. He lists nine rust fungi that infect Cymbopogon but does not list P. cesatii. Of these nine species, only P. cymbopogonis is morphologically similar. Further research is needed to investigate the potential impact of rust fungi on lemongrass production and to elucidate phylogenetic relationships of rust fungi infecting lemongrass.

First Report of Colletotrichum sansevieriae Causing Anthracnose of Snake Plant (Dracaena trifasciata) in Ohio and its Draft Genome

Dracaena trifasciata (Prain) Mabb. is a popular houseplant in the United States. In September 2021, two diseased samples from two Ohio homeowners were received by the Ornamental Pathology Laboratory at The Ohio State University. Each sample included one or two detached leaves displaying circular gray water-soaked lesions scattered throughout the lamina and blighted areas with concentric rings bearing brown to black acervuli. Lesions covered between 25 and 50% of the leaf surface. Isolations were made by excising small portions of leaf tissue from the margin of the lesions, surface-disinfesting in 10% bleach for 45 s, rinsing in sterile water, and plating on potato dextrose agar (PDA). Plates were incubated at 23°C for one week. Two representative isolates, one per sample (FPH2021-5 and -6), were obtained by transferring hyphal tips to fresh PDA plates. Mycelia of both isolates were aerial, cottony, grayish-white, producing spores in a gelatinous orange matrix, and appeared gray to olivaceous-gray on the plate underside. Conidia produced by both isolates were cylindrical, single-celled, hyaline, measuring 12.02 to 18.11 (15.51) × 5.03 to 7.29 (6.14) μm (FPH2021-5; n=50) and 15.58 to 20.90 (18.39) × 5.63 to 8.27 (7.05) μm (FPH2021-6; n=50). Appressoria were globose to subglobose, single-celled, dark brown to sepia, measuring 6.62 to 13.98 (8.97) × 5.05 to 6.58 (6.58) μm (FPH2021-5; n=50), and 6.54 to 11.32 (8.63) × 4.54 to 8.94 (7.09) μm (FPH2021-6; n=50). Genomic DNA (gDNA) samples were extracted from both isolates and the internal transcribed spacer (ITS) region was amplified using primers ITS1F/ITS4 (Gardes and Bruns, 1993; White et al. 1990). GenBank BLAST sequence analysis resulted in 99.83% (FPH2021-5; GenBank Acc. No. OP410918.1) and 100% (FPH2021-6; OP410917.1) identity with 100% query coverage to the type strain of Colletotrichum sansevieriae Miho Nakam. & Ohzono MAFF239721 or Sa-1-2 (NR_152313.1; Nakamura et al. 2006). Whole genome sequencing was conducted for FPH2021-6 and the assembly was deposited in GenBank (JAOQIF000000000.1). The glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and β-tubulin (β-tub) regions were either extracted from the genome of FPH2021-6 (OP414603.1 and OP414601.1, respectively) or amplified from FPH2021-5 gDNA using primers GDF/GDR (OP414604.1) and Bt-2b/T1 (OP414602.1), respectively (Templeton et al. 1992; Glass and Donaldson 1995; O'Donnell and Cigelnik 1997). A multilocus partitioned analysis (Chernomor et al. 2016) based on concatenated sequences of ITS, GAPDH, and β-tub using ModelFinder (Kalyaanamoorthy et al. 2017) was performed to build a maximum likelihood tree (IQ-TREE v2.0.3; Nguyen et al. 2015), suggesting that these two isolates are phylogenetically closer to the type strain from Japan than to a previously reported isolate 1047 from Florida (Palmateer et al. 2012). To fulfill Koch's postulates, two parallel leaf sections from one 10-inch D. trifasciata 'Laurentii' plant maintained in a 1.3-liter container were selected. Three wounds were made in each section using a sterile syringe needle. A 10-µl drop of either a 1×106 conidia/ml suspension of isolate FPH2021-6 or sterile water was placed on each wound. The plant was covered with a plastic bag for two days post-inoculation (DPI) and maintained in a greenhouse at 25°C with a 12- h photoperiod. The experiment was conducted twice. Grayish water-soaked lesions, acervuli, and leaf blight were observed on the inoculated sections 3, 10, and 14 DPI, respectively, while no symptoms appeared on the sections treated with sterile water. C. sansevieriae was re-isolated from the lesions and confirmed to be identical to the original isolate based on ITS sequencing and morphological examinations. To the best of our knowledge, this is the first report of C. sansevieriae on D. trifasciata in Ohio and the first genome draft of an isolate from the United States. Availability of whole-genome sequence data is paramount for resolving species identification in this highly diverse fungal genus, and a powerful tool to conduct comparative genomic analyses in the future.

First Report of Pseudomonas syringae Causing Bacterial Leaf Spot on Winterberry Holly (Ilex verticillata) in Ohio

Winterberries (Ilex verticillata and hybrids) are deciduous species of holly whose branches bearing colorful fruit are cut in late Fall to be used for seasonal decorations. The annual wholesale value of the woody cuts is $1.5 million nationally (NASS, 2019). In June 2021, approximately 80% of the 45 Ilex verticillata 'Maryland Beauty' potted plants, which were maintained in a container yard at The Ohio State University research farm in Columbus, OH, presented leaves with irregular necrotic lesions surrounded by a chlorotic halo. No other symptoms were present on the plants. Bacterial streaming was observed from the lesions using a compound microscope and isolations were performed after surface disinfesting small sections of leaf tissue from the border of the lesions by soaking in 10% bleach for 30 sec, rinsing twice in sterile water, macerating in sterile water, and streaking the suspension on nutrient broth yeast extract agar. Creamy white, circular, smooth, and convex colonies were recovered after incubation at 28°C for 48 h. Bacterial identification of one representative isolate was initially pursued from single colonies of a purified culture using five discriminative phenotypic tests (i.e., LOPAT: "L", levan production; "O", oxidase activity; "P", pectinolytic activity; "A", arginine dehydrolase production; "T", tobacco hypersensitive reaction), which resulted in the L+ O- P- A- T+ profile consistent with the description of Pseudomonas syringae (Lelliott et al. 1996). Molecular identification was performed based on rpoD marker amplification and sequencing using primers PsrpoD FNP1/PsrpoDnprpcr1 (Parkison et al. 2011). NCBI GenBank BLASTn comparison of the rpoD sequence (GenBank Acc. No. OP221440) shared 99.12% identity to P. syringae pv. passiflorae (AB163366.1). Whole genome sequence analysis was conducted to strengthen the classification of the isolate species. To this extent, DNA was sequenced with an iSeq 100 Illumina benchtop sequencer using Illumina DNA Prep kit and iSeq 100 i1 Reagent v2 (Illumina, Inc, REF: 20060060 and 20031371). Illumina Local Run Manager software was used for base calling, demultiplexing, and trimming of the raw reads. Unicycler v0.5.0 was used for de novo assembly of the genome (Wick et al. 2017). The assembled genome size was 5.9 Mb with 959 contigs and 10× coverage (NCBI GenBank Biosample No. SAMN30281368; Acc. No. JANQCB010000000). Average nucleotide identity (ANI) analysis was performed on the server MiGA online (Rodriguez-R et al. 2018). Subgroup identification was inconclusive (p>0.05), positioning this isolate between P. syringae pv. actinidiae (96.45% ANI) and pv. viburni (96.65% ANI) (Rodriguez-R & Konstantinidis, 2016). Both these pathovars cause leaf spots on woody plants such as kiwi and viburnum (Donati et al. 2020; Garibaldi et al. 2005). To confirm pathogenicity, three separate branches on each of two I. verticillata 'Maryland Beauty' potted plants were selected, and 5-7 individual young leaves (>2 weeks from emergence) on each branch were infiltrated with a bacterial suspension (108 CFU/mL) in sterile water (SW) using a needleless syringe by delivering 30-50 µL of suspension per infiltration point. One additional branch per plant was infiltrated with SW to serve as control. Plants were covered with a plastic bag for two days post-inoculation (DPI) and maintained in the laboratory at an average of 23°C. All inoculated leaves showed necrotic lesions two DPI while control leaves remained asymptomatic. To fulfill Koch's postulates, the bacterium was re-isolated from the symptomatic leaves six DPI and confirmed to be identical to the original isolate based on rpoD gene sequencing. To the best of our knowledge, this report signifies the first instance of P. syringae causing bacterial leaf spot on winterberry worldwide. Ornamental plant sales are based primarily on visual appeal; therefore, identification and monitoring of emerging pathogens is essential to ensure the health of the industry.

First Report of Erysiphe alphitoides Causing Powdery Mildew of Cocculus orbiculatus in China

Cocculus orbiculatus (L.) DC. (Menispermaceae) is a vine traditionally used as a medicinal herb in Asia and grows primarily in wet tropical biomes (POWO 2022). In late April 2022, typical symptoms of powdery mildew were observed on leaves of C. orbiculatus on the campus of Nanjing Forestry University, China. Approximately 90% of the plants were infected. Superficial mycelia and conidia were amphigenous on the leaves, pale yellow, and severe infections caused necrotic discoloration of the leaves. Infected leaves were collected to identify the pathogen. Hyphae were hyaline and branched. Conidiophores were solidary, unbranched, straight, cylindrical, smooth, hyaline, 69.3 ± 11.1 × 7.9 ± 0.6 µm, (n = 50). Foot cells were mostly cylindrical, straight, rarely curved, smooth, hyaline, 53.2 ± 6.2 × 7.5 ± 0.4 µm, (n = 50). Appressoria were lobulate, solitary or in opposite pairs, hyaline to pale yellow. Conidia were single, ellipsoid, oval or doliform, hyaline or pale yellow, 38.6 ± 2.3 × 20.9 ± 0.8 µm, (n = 50). Conidial germ tubes developed at a subterminal position. No chasmothecia were observed. Representative specimens were deposited in the NJFU Herbarium (NF50000010). Based on these morphological characteristics, this fungus (MFJ 1-1) was provisionally identified as Erysiphe alphitoides (Takamatsu et al. 2007). To verify the identification of the pathogen, mycelia and conidia were obtained from diseased leaves and genomic DNA of the fungus (MFJ 1-1) was extracted. The internal transcribed spacer region (ITS) and large subunit (LSU) gene were amplified with primers ITS1/ITS4 and LR0R/LR5, respectively (White et al. 1990, Rehner and Samuels 1994). The sequences were deposited in GenBank (ON612134 for ITS, ON620080 for LSU). BLAST results showed that the ITS and LSU sequences were highly similar to E. alphitoides [ITS: KF734882, identities = 632/633 (99%) LSU: MK357414, identities = 890/893 (99%)]. Phylogenetic analyses with the concatenated sequences using Bayesian inference and maximum likelihood placed the isolate in the clade of Erysiphe alphitoides. Pathogenicity was confirmed by gently pressing the infected leaves onto five leaves per plant, and three healthy plants were inoculated. Three uninoculated plants served as controls. The plants were placed in a growth chamber with a 16 h photoperiod at 22 ± 2°C, 70% of relative humidity. Symptoms developed 10 days after inoculation, whereas the control leaves remained symptomless. The powdery mildew developing on the inoculated plants was identified to be E. alphitoides based on morphological characters and ITS sequences. This fungus has a worldwide distribution and a broad host range. Recently, Ipomoea obscura (Pan et al. 2020) and Aegle marmelos (Banerjee et al. 2020) have been found to be additional hosts. To our knowledge, this is the first report of powdery mildew caused by E. alphitoides on C. orbiculatus in the world. This finding provides crucial information for developing effective strategies to monitor and manage this disease.

First report of Nigrospora sphaerica associated with leaf spot disease of Crossandra infundibuliformis in India

Crossandra (Crossandra infundubuliformis (L.) Nees.) is one of the main floriculture crops in Karnataka. In 2020 (March-June), a characteristic leaf spot disease of unknown etiology with an incidence ranging from 10-12% (~30 ha area evaluated) was observed in Southern Karnataka (Mysore, Mandya). Initially, the symptoms developed as small specks (3 to 8 mm), characterized by circular to irregular shapes in the beginning and coalesced to form larger lesions. Ten samples were collected in polybags followed by the isolation of associated fungal pathogen on potato dextrose agar (PDA) medium amended with Chloramphenicol (60 mg/L). Briefly, small pieces of infected leaves were cut into small pieces and surface sterilized with 2% sodium hypochlorite (NaOCl) solution, rinsed three times with sterile distilled water (SDW), blot dried, then inoculated onto PDA medium, and incubated at room temperature (27 ± 2°C) for 3 - 5 days. Fungal colonies developed from the segments and were subcultured through hyphal tipping to fresh PDA plates to get pure cultures. A total of 12 pure cultures were obtained. Mycelia were initially white and eventually turned gray. The conidia were black, single-celled, smooth, spherical to subspherical, 9 to 18 μm in diameter (n=50), and borne singly on a hyaline vesicle at the tip of each conidiophore. The identity was initially established based on the cultural features and conidial morphology as Nigrospora sp. (Deepika et al., 2021). To confirm the identity of fungal isolates based on molecular sequence analysis was performed for two representative isolates (CIT1 & CIT2). ITS-rDNA, tub2 & EF-1α gene were amplified using primers ITS1/ITS4, T1/T22 & EF1-728F/986R (White et al., 1990; O'Donnel and Cigelnik, 1997; Carbone and Kohn, 1999), then purified and sequenced. The BLASTn analysis of ITS, tub2 and EF-1α gene showed 99-100% similarity with reference sequences from the GenBank database to Nigrospora sphaerica (ITS: 520bp, KX985935 - LC7312; MH854878 - CBS:166.26; tub2: 357bp, MZ032030 - WYR007, 350bp, KY019606 - LC7298, KY019522 - LC4278, KY019520 - LC4274; EF-1α: 472bp, KY019397 - LC7294, KY019331 - LC4241; MN864137 - HN-BH-3) and the sequences were deposited in GenBank (ITS: OL672271 & OL672272; tub2: OL782120 & OL782121; EF-1α: ON051604 & ON051605) (Wang et al., 2017). The associated fungal pathogen was identified as N. sphaerica (Sacc.) Mason (Chen et al. 2018; Deepika et al., 2021) based on the cultural, morphological, microscopic, and molecular characteristics. Further, pathogenicity tests were conducted on healthy plants (Crossandra cv. Arka; n=30) grown under greenhouse conditions (28±2 °C; 80% RH). Inoculations were made with conidial suspension (18 days old N. sphaerica isolate CIT1, 106 conidia/ml) prepared in SDW, and healthy plants sprayed with SDW (n=10) served as controls. All the plants were covered with polyethylene bags for 24-48 hr and observations were made at regular intervals. Typical necrotic lesions developed on 16 plants after 12 days after inoculation but no symptoms were observed on the control plants. The associated pathogen was re-isolated from diseased leaves and confirmed their identity based on morphology and cultural characteristics. Earlier, N. sphaerica was associated with various tree species as an endophyte, and recently several reports have appeared to cause disease on various crop plants (Deepika et al., 2021). However, there are no previous reports on the association of N. sphaerica causing leaf spot disease on C. infundibuliformis from India. Early diagnosis of this leaf spot disease will help the floriculturist adopt suitable management practices to avoid significant economic loss.

Combating an Invasive Boxwood Pathogen - Calonectria pseudonaviculata - in the United States by Shifting Production to Less Susceptible Cultivars

Boxwood Blight (BB) caused by Calonectria pseudonaviculata (Cps) is an economically devastating disease affecting the entire boxwood supply chain from growers to gardeners, since it was first officially documented in the United States in 2011. This disease has taken a heavy toll on boxwood, an iconic landscape plant and the number one evergreen nursery crop. The objective of this study was to examine the adoption of one sustainable management strategy available to growers: shifting boxwood production from highly susceptible to less susceptible cultivars. We investigated the ongoing shift by comparing boxwood sales of 17 selected nurseries from seven states across the country in 2011, 2016 and 2021. Results revealed that from 2021 to 2016, sales of cultivars highly susceptible to BB were reduced by over 35% while less sales of less susceptible boxwood cultivars increased 55%. Increased boxwood sales have been seen for 'Winter Gem', 'Wintergreen', 'SB 300' (Freedom®), 'SB 108' (Independence®), and 'Little Missy', all of which have been rated less susceptible than B. sempervirens 'Suffruticosa' in numerous trials. The potential for long-term positive impact on sustainable boxwood production and plantings in the U.S. through the use of such less susceptible cultivars is discussed. Better boxwood cultivar choices will build crop health into new plantings and sustain customer demand for boxwood. This is a case study for how sustainable crop protection strategy helps to maintain production of a crop under serious pressure from an invasive pathogen.