First Report of Anthracnose on Banana Peppers Caused By Colletotrichum scovillei in New York.

In early August 2023, a disease outbreak on hot banana peppers (Capsicum annuum cv. Golden Dagger) was reported in Cattaraugus County, New York (NY). Disease incidence was at least 60%. Affected developing and mature fruit had at least one tan, soft, sunken lesion with salmon-colored spore masses surrounded by brown, necrotic margins. Microscopic observation of the lesions identified acervuli and setae typical of Colletotrichum spp. Isolations were made from these lesions by spreading conidia from the acervuli on 2% water agar (WA) + 0.02% (w/v) ampicillin. Colonies were hyphal tipped and transferred onto clarified V8 juice agar (CV8) and incubated at 20°C. The isolation frequency was 100% and a total of six isolates were obtained: Coll23Pep001, Coll23Pep003, Coll23Pep005, Coll23Pep007, Coll23Pep008, and Coll23Pep010. After 10 days, colonies were subcultured to potato dextrose agar (PDA) and CV8. On PDA, colonies appeared off-white to dark gray with sparse aerial mycelia. On CV8, the colony was pale gray with acervuli and orange-colored spore masses in the center. Conidia were hyaline, smooth and fusiform to round, and tapered at both ends. Mean conidial dimensions (n = 20) were 20.2 (13.75 to 25) µm long × 4.7 (3 to 6.25) µm wide. To confirm the identity of the isolates, DNA was extracted, and PCR performed to amplify the internal transcriber spacer (ITS) region (primers ITS1/ITS4; White et al. 1990), and actin (ACT) (primers ACT-512F/ACT-783R; Carbone and Kohn 1999) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes (primers GDF1/GDR1; Guerber et al. 2003). Pairwise alignment of the sequences showed all isolates had 100% similarity to C. scovillei ex. holotype CBS 126529 (Damm et al. 2012). Sequences from all isolates were deposited in GenBank with accessions PP556967 to PP556972 (ITS), PP565766 to PP565771 (ACT), and PP565772 to PP565777 (GAPDH). For pathogenicity testing, all isolates were grown on CV8 at 20°C in the dark for 10 days. Conidia were harvested by flooding the plates of each isolate with sterile distilled water and filtering the suspension through a double layer of cheesecloth. The concentration of the conidial suspension was adjusted to 5 × 105 spores per ml. Pathogenicity of the six isolates was tested on banana pepper fruit by using a sterile toothpick to pierce the skin at the two opposite ends. A droplet (10 µl) of the conidial suspension was placed on each wound. The same number of fruit were inoculated without wounding, and non-inoculated control fruit received a droplet of sterile distilled water (either wounded or unwounded). The experiment was repeated twice. All fruit were placed in a humid box at room temperature for 7 days. All wounded and inoculated fruit developed sunken lesions filled with salmon-colored conidial masses. Disease did not occur on the unwounded, inoculated fruit nor the non-inoculated controls. C. scovillei was recovered from all inoculated fruit by reisolating onto CV8 media and isolates had similar morphology and conidial dimensions to the original isolates. To the best of our knowledge, this is the first report of C. scovillei causing anthracnose on pepper in NY. C. scovillei has been reported in South Carolina (Toporek and Keinath 2021), Brazil (Caires et al. 2014), eastern Asia (de Silva et al. 2019), and Kosovo (Xhemali et al. 2023). The pathogen is particularly aggressive on pepper and poses substantial threats to pepper production around the world.

Nighttime Applications of Germicidal Ultraviolet Light (UV-C) to Suppress Cercospora Leaf Spot in Table Beet.

Cercospora leaf spot (CLS), caused by the hemibiotrophic fungus Cercospora beticola, is a destructive disease affecting table beet. Multiple applications of fungicides are needed to reduce epidemic progress to maintain foliar health and enable mechanized harvest. The sustainability of CLS control is threatened by the rapid development of fungicide resistance, the need to grow commercially acceptable yet CLS-susceptible cultivars, and the inability to manipulate agronomic conditions to mitigate disease risk. Nighttime applications of germicidal ultraviolet light (UV-C) have recently been used to suppress several plant diseases, notably those caused by ectoparasitic biotrophs such as powdery mildews. We evaluated the efficacy of nighttime applications of UV-C for suppression of CLS in table beet. In vitro lethality of UV-C to germinating conidia increased with increasing dose, with complete suppression at 1,000 J/m2. Greenhouse-grown table beet tolerated relatively high doses of UV-C without lethal effects despite some bronzing on the leaf blade. A UV-C dose >1,500 J/m2 resulted in phytotoxicity severities greater than 50%. UV-C exposure to ≤750 J/m2 resulted in negligible phytotoxicity. Older (6-week-old) greenhouse-grown plants were more susceptible to UV-C damage than younger (2- and 4-week-old) plants. Suppression of CLS by UV-C was greater when applied within 6 days of C. beticola inoculation than if delayed until 13 days after infection in greenhouse-grown plants. In field trials, there were significant linear relationships between UV-C dose and CLS control and phytotoxicity severity, and a significant negative linear relationship between phytotoxicity and CLS severity at the final assessment. Significant differences between UV-C doses on the severity of CLS and phytotoxicity indicated an efficacious dose near 800 J/m2. Collectively, these findings illustrate significant and substantial suppression by nighttime applications of UV-C for CLS control on table beet, with potential for incorporation in both conventional and organic table beet broadacre production systems.

Survival of Sclerotinia sclerotiorum Sclerotia in Central New York.

White mold caused by Sclerotinia sclerotiorum is a serious disease affecting many field and specialty crops in New York (NY). The primary inoculum for white mold is sclerotia that are hardened masses of mycelia that survive adverse environmental conditions and periods of non-hosts. However, NY crop guidelines lack rotation and residue management recommendations based on local knowledge of sclerotial survival. A field trial was established in October 2020 by deploying S. sclerotiorum sclerotia in mesh bags on the soil surface or shallowly buried (placed at 3 cm depth in the soil) at Geneva, NY. Bags were periodically collected from 67 to 769 days. At each time, sclerotial retrieval (number of sclerotia) was assessed by counted and viability evaluated through myceliogenic germination. Sclerotial retrieval was significantly affected by soil depth and was higher in those on the surface than buried. Time also affected the retrieval of sclerotia which was significantly reduced after 250 days. The interaction between burial and time had a significant effect on sclerotial viability. Approximately 15% of sclerotia placed on the surface were still viable after 769 days. After 433 days, viability of buried sclerotia was also significantly reduced compared to those on the surface. After 670 days, none of the buried sclerotia were viable. These findings suggest a rotation of at least two years between susceptible crops is required to reduce primary inoculum. However, given that low inoculum densities are sufficient to initiate a white mold outbreak, a longer rotation may be beneficial. In a cultivated system, timely tillage of crop residue to bury sclerotia after harvest to promote degradation is encouraged.

First Report of Cucurbit Yellow Vine Disease Caused by Serratia marcescens on Cucurbits in New York.

Cucurbits are one of the most significant commodities in New York, with a value of $92.3 million in 2021 (NASS-USDA 2021). In August 2021, several acorn squash (Cucurbita pepo) cultivar Turbinate plants at Cornell AgriTech research farm in Geneva, NY, had chlorotic, wilting leaves, and older leaves appeared scorched. The phloem of stems, bisected at the crown, had a honey-brown discoloration. The incidence of symptomatic plants was 22% in a one-acre planting field. Most of the symptomatic plants rapidly declined and died. The following year, similar symptoms were observed on muskmelon (Cucumis melo), acorn squash, and winter squash (C. pepo) cultivar Bush Delicata at the same location. These symptoms were typical of Cucurbit Yellow Vine Disease (CYVD) caused by the Gram-negative bacterium Serratia marcescens (Bruton et al. 1998, 2003). Moreover, a high incidence of squash bugs (vector of CYVD) was observed. To identify the causal agent, 45 stems from the symptomatic Bush delicata plants were collected. Each stem was cut into small pieces (2 to 3 mm), surface sterilized with 70% ethanol for 60 sec, 10% bleach for 60 sec, and rinsed with sterile water. The tissue was macerated in sterile water, and the resultant suspension was streaked on King's B (KB) medium (King et al. 1954). Plates were incubated at 28°C for 24 h, and 11 developed white, round bacterial colonies that were smooth and creamy in appearance. Single colonies were transferred to new KB plates and incubated for 24 h. The genomic DNA of two isolates (22212 and 22213) was extracted with the Wizard® Genomic DNA Purification Kit Protocol (Promega, Madison, WI). PCR was carried out using YV1 and YV4 primers specific to the 16S rDNA region of S. marcescens and 79F/R primers specific for S. marcescens causing CYVD (Zhang et al. 2005). The DNA sequence of each PCR product was obtained using Sanger sequencing and submitted to GenBank. Accessions OQ584799 and OQ584800 for YV1/YV4 (isolates 22212 and 22213, respectively) exhibited 100% identity to S. marcescens (384/384 bp, nearest accession identity: CP083754). Accession numbers OQ693911 and OQ693912 for 79F/R showed 99% identity to S. marcescens isolates (309/313 bp, nearest accession identity: CP033623). To fulfill Koch's postulates, Bush Delicata squash plants were grown for two weeks in a greenhouse, and three plants per isolate were inoculated using S. marcescens 22212 and 22213, three plants with Escherichia coli DH5a as a non-pathogenic control, distilled water as a mock-inoculated control, and a noninoculated control. Inoculation was performed by taking a single bacterial colony with a small pin and puncturing the plant's lower stem four to five times (Bruton et al. 2003). Twenty-eight days after inoculation, three of the six plants inoculated with the two S. marcescens isolates (two from 22212 and one from 22213) developed CYVD symptoms as observed in the field. Isolations were made from the stems of symptomatic plants and the mock-inoculated controls. PCR was conducted using YV1/YV4 primers and 79F/R primers (Zhang et al. 2005). Only isolations from symptomatic plants amplified with these primers and PCR products were sequenced. These sequences were identical to the original isolates. To our knowledge, this is the first report of CYVD and phytopathogenic S. marcescens in New York. The impact of CYVD can be substantial, with losses up to 100% (Zhang et al. 2005). Therefore, more knowledge on S. marcescens is needed to determine its biology and prevalence in New York.

First Report of Halo Blight on Hop Caused by Diaporthe humulicola in New York.

In late July and August 2015, foliar disease was observed in three hop (Humulus lupulus; unknown cultivars) yards in Ontario, Otsego, and Putnam counties, New York (NY). Disease incidence ranged between 70 and 90% of plants, and up to 25% of the leaves per plant were affected. Leaf symptoms were large, necrotic patches with a chlorotic halo (2 to 10 cm diam.). Leaves and dry, easily shattered cones were placed at high humidity for 10 days. Pycnidia were abundant in leaf lesions which extruded conidia. Pycnidia were also observed on cone bracts and bracteoles. Fifteen isolations were made from each yard by placing a pycnidium onto 2% water agar + 0.02% (w/v) ampicillin. Colonies were hyphal tipped and transferred to potato dextrose agar (PDA) before incubation at 20°C with a 12-h photoperiod. Colonies on PDA had flat mycelia and were white to cream in color. The isolation frequency was 100%. To induce sporulation, five isolates were grown on PDA with autoclaved alfalfa stems for 7 to 10 days. Alpha conidia were hyaline, and oval with obtuse ends. Mean alpha conidial dimensions were (n = 20): 9.1 m × 3.4 µm (BE1; Ontario Co.); 11.8 × 3.8 µm (BE34; Ontario Co.); 9.6 × 4.1 µm (BE10; Ontario Co.); 10.2 × 3.7 µm (BE52; Otsego Co.); and 10.3 × 3.6 µm (BE69; Putnam Co.). Beta conidia were not observed. DNA was extracted and PCR performed to amplify the internal transcribed spacer (ITS) region (primers ITS1/ITS4; White et al. 1990), translation elongation factor 1-α (TEF; EF1-728F/EF1-986R; Carbone and Kohn 1999), a partial region of ß-tubulin (TUB; Bt2a/Bt2b; Glass and Donaldson 1995), a partial region of histone 3 (H3) (H3; CYLH3F/H3-1b Crous et al. 2004), and calmodulin (CAL; CAL-228F/CAL2Rd; Groenewald et al. 2013) genes. For all NY isolates, sequence similarity was >99% to D. humulicola CT2018-3 for the ITS region, and TEF, HIS, and CAL genes. Sequence similarity to CT2018-3 for the TUB region ranged from 86.96% (BE-1) to 96.15% (BE-10). . Analyses with the ITS, TEF, CAL, and HIS sequences supported our identification of the NY isolates as D. humulicola. Sequences were deposited in GenBank (OM370960 to OM370984). For pathogenicity testing, BE-34 and BE-69 were grown on PDA + autoclaved alfalfa stems at room temperature and a 12-h photoperiod for 10 days. Conidia were harvested by flooding the plate with sterile water. Conidial concentration was quantified, and the inoculum suspension diluted to ~5  105 (+ 0.01% polysorbate-20)/ml. Five cv. Cascade plants were sprayed with inoculum until run-off and covered with a plastic bag for 72 h. Non-inoculated control plants were sprayed with 0.01% polysorbate-20 and bagged. Plants were placed in a misting chamber and exposed to alternating 25°C light/18°C dark with a 16 h photoperiod. Mist was applied for 1 h daily. Necrotic lesions like the field specimens were observed on all inoculated plants after 28 days with no symptoms on control plants. Diseased leaves were detached and placed in a humid chamber for 2 days, and pycnidia observed in lesions. The reisolation frequency of D. humulicola was 100%. Conidia from the isolates had similar morphology to the original isolates. This is the first report of halo blight caused by D. humulicola on hop in NY. Halo blight has been reported on hop and associated with significant yield loss through cone shattering in MI (Higgins et al. 2021), CT (Allan-Perkins et al. 2020), and Quebec, Canada (Hatlen et al. 2021). Research is needed to determine if management is warranted.

The global burden of pathogens and pests on major food crops.

Crop pathogens and pests reduce the yield and quality of agricultural production. They cause substantial economic losses and reduce food security at household, national and global levels. Quantitative, standardized information on crop losses is difficult to compile and compare across crops, agroecosystems and regions. Here, we report on an expert-based assessment of crop health, and provide numerical estimates of yield losses on an individual pathogen and pest basis for five major crops globally and in food security hotspots. Our results document losses associated with 137 pathogens and pests associated with wheat, rice, maize, potato and soybean worldwide. Our yield loss (range) estimates at a global level and per hotspot for wheat (21.5% (10.1-28.1%)), rice (30.0% (24.6-40.9%)), maize (22.5% (19.5-41.1%)), potato (17.2% (8.1-21.0%)) and soybean (21.4% (11.0-32.4%)) suggest that the highest losses are associated with food-deficit regions with fast-growing populations, and frequently with emerging or re-emerging pests and diseases. Our assessment highlights differences in impacts among crop pathogens and pests and among food security hotspots. This analysis contributes critical information to prioritize crop health management to improve the sustainability of agroecosystems in delivering services to societies.