Green fruit anthracnose caused by the fungus Colletotrichum scovillei is an emerging disease on various types of peppers (Capsicum spp.) in the Eastern United States. Sixteen cultivars, representing 11 horticultural fruit types from four species of Capsicum, C. annuum, C. baccatum, C. chinense, and C. frutescens, were evaluated for potential fruit rot resistance to Colletotrichum scovillei in replicated field plots in summer 2022 and 2023. Fruit was naturally inoculated by facilitating the spread of conidia of Colletotrichum scovillei with overhead irrigation from inoculated jalapeño fruit on plants located between plots into test plots. Capsicum chinense cultivars Roulette and Carolina Reaper and C. frutescens cultivars Tabasco and Malagueta had significantly lower fruit disease incidence than the other 12 cultivars in both years. In a second experiment, conducted in fall 2022 and 2023, four C. annuum pepper types were treated or not treated with a preventive rotation of mancozeb and azoxystrobin at labeled rates. The fungicide treatment reduced fruit disease incidence fivefold compared with the nontreated control in both years. In the nontreated plots, the reduced susceptibility of jalapeño, New Mexico chili, and Italian frying peppers provided 50% fruit rot control relative to susceptible bell pepper. In fungicide-treated plots, however, mean percentage control was 80% for the nonbell cultivars. In 2022, marketable weight and number were fivefold greater on fungicide-treated plants than nontreated plants, but in 2023, yields were not affected by fungicides. Capsicum frutescens may be useful as a source of resistance to develop new pepper cultivars that would help growers manage green fruit anthracnose.

Cottony leak, a soft rot on fruit of cucurbit crops, is a concern for pickling cucumber (Cucumis sativus cv. Gershwin) growers in South Carolina and other states. Fruit with typical symptoms and signs of cottony leak were sampled from five commercial fields in 2022 and 2023. Most isolates (28) recovered from symptomatic fruit were identified as Pythium deliense, and the remaining five isolates were P. aphanidermatum, based on sequences of the mitochondrially encoded cytochrome c oxidase subunit 1 gene. P. deliense also was recovered from stem lesions on two seedlings. In pathogenicity tests, P. aphanidermatum was more virulent on pickling cucumber fruit of cv. Kirby, whereas P. deliense was more virulent on seedlings of cv. Gershwin. Recovery of Pythium spp. from symptomatic fruit was greater (P = 0.05) in fields cropped to peanut (Arachis hypogea) or soybean (Glycine max) (83.3 ± 7.6% of fruit), hosts of P. deliense, than to coastal bermudagrass (Cynodon dactylon) (55.0 ± 11.7% of fruit), a nonhost, 2 years before planting cucumber. Planting crops that are nonhosts of P. deliense for 2 years before pickling cucumber may help to reduce the incidence of cottony leak. This is the first report of P. deliense as a causal agent of cottony leak on cucurbit fruit.

Curly kale (Brassica oleracea var. sabellica), a popular leafy green vegetable, is marketed mainly for fresh consumption as bunches of leaves or as chopped, bagged leaves. Two pieces of leaves with symptoms of white mold were found in a bag of kale packaged in South Carolina and purchased in December 2025. Two isolates of Sclerotinia sclerotiorum were obtained and identified based on morphology, sclerotia production, and the sizes of expected amplicons produced by species-specific primers in conventional PCR. Colonized agar plugs were used as sources of inoculum in two pathogenicity tests originally developed to inoculate canola with S. sclerotiorum. Both isolates were pathogenic on kale seedlings inoculated by placing a plug in the middle of four seedlings or by placing a plug contained in a pipette tip on a cut petiole. Petiole inoculation at 22.5°C resulted in a greater percentage of diseased plants (85%) than seedling inoculation (13%) and is recommended for future use with S. sclerotiorum and kale. In an additional test with petiole inoculation done at 5°C, a temperature close to postharvest conditions, 91.5% of plants became diseased. Growers are advised to consider the application of fungicides effective against white mold before harvesting kale to be marketed as ready-to-eat chopped and bagged leaves when environmental conditions in the field prior to harvest favor ascospore dispersal.

Phomopsis blight caused by the fungus Diaporthe vexans is commonly found on eggplant (Solanum melongena) leaves, stems, and fruits in the fall growing season in the southeastern United States. The objective of this study was to determine which of 10 fungicides currently registered on eggplant are effective against Phomopsis leaf blight. Field experiments were done in fall 2023, 2024, and 2025 with 10 fungicides applied preventatively before plants were inoculated with conidial suspensions of D. vexans. Chlorothalonil was used as the rotation partner with fungicides that required applications to be alternated with a different active ingredient. Plants treated with mefentrifluconazole (Cevya, Fungicide Resistance Action Committee [FRAC] Code 3), cyprodinil + difenoconazole (Inspire Super, FRAC 9+3), and difenoconazole + benzovindiflupyr (Aprovia Top, FRAC 3+7), all rotated with chlorothalonil (Bravo WeatherStik, FRAC 05), had significantly less foliar necrosis than the water control in 2023 and 2025; these three treatments did not differ significantly from each other. Pyraclostrobin + fluxapyroxad (Priaxor FRAC 11 + 7) also reduced foliar necrosis in 2023. Pyraclostrobin (Cabrio, FRAC 11) and boscalid (Endura, FRAC 7), both rotated with chlorothalonil, as well as chlorothalonil, chlorothalonil + zoxamide (Zing!, M05 + 22), copper oxychloride + copper hydroxide (Badge X2, FRAC M01), and chlorothalonil + cymoxanil (Cymbol Advance FRAC M05 + 27), were ineffective. The results of this study can be used to refine fungicide recommendations to manage Phomopsis blight on eggplant in the United States.

Fusarium wilt, caused by Fusarium oxysporum f. sp. niveum (FON), limits triploid watermelon (Citrullus lanatus) production severely in the southeastern United States, particularly in fields infested with FON race 2. A 2-year field study was conducted at locations in North Carolina and South Carolina, USA, to evaluate Fusarium wilt resistance and yield of commercial triploid cultivars. Grafted treatments were also evaluated yearly. Nongrafted cultivars showed moderate to high susceptibility to Fusarium wilt, with considerable variation in disease progression and yield. Disease incidence for 'Shoreline' ranged from 67.6% to 100% across both years and locations. 'Fascination' had 24.3% to 83.9% disease incidence and 'Tri-X-313' had 37.1% to 99.4% disease incidence across both years and locations. 'Fascination' grafted on the FON race 2-resistant rootstock 'Carolina Strongback' exhibited consistently near-zero disease incidence and area under the disease progress curve (AUDPC) values, and demonstrated the greatest marketable yield across all site-years. A strong negative correlation between AUDPC and yield was observed at both states. Grafting onto resistant rootstocks offers a highly effective strategy for managing Fusarium wilt and improving yield in infested fields. Results also highlight the need for continued cultivar evaluation and development of triploids with improved FON resistance.

Cucurbit crops including watermelon (Citrullus lanatus), melon (Cucumis melo), cucumber (Cucumis sativus), squash, and pumpkin (Cucurbita spp.) make important nutritional and flavorful contributions to the human diet. The primary challenge for US cucurbit production is disease caused by numerous fungal, oomycete, bacterial, and viral pathogens that reduce crop yield and quality and engender costly control measures. The USDA National Institute of Food and Agriculture–Specialty Crop Research Initiative funded CucCAP (Cucurbit Coordinated Agricultural Project) projects “CucCAP: Leveraging applied genomics to improve disease resistance in cucurbit crops” and “CucCAP2: Harnessing genomic resources for disease resistance and management in cucurbit crops–Bringing the tools to the field” brought together members of the cucurbit community across the country with expertise in genomics, bioinformatics, breeding, genetics, plant pathology, integrated disease management, and economics to address these disease challenges. Collectively, the projects produced extensive genomic resources and bioinformatic tools including genome assemblies and pan-genomes for cucurbit species; genetically characterized the full US National Plant Germplasm System (NPGS) collections for watermelon, melon, cucumber, and squash; developed deeply resequenced core populations for these crops; identified single nucleotide polymorphism and structural variants; and developed the Cucurbit Genomics database (CuGenDB, http://cucurbitgenomics.org/v2/). New sources of resistance were identified for 17 cucurbit crop/disease combinations; quantitative trait loci were mapped and molecular markers developed for 24 combinations; and 15 breeding lines with resistances to various diseases were released. New detection methodology was developed for several pathogens; extensive disease monitoring and multilocation disease management trials and resistance tests were performed; a centralized web portal (https://cuccap.org) was developed to provide cucurbit disease information in English and Spanish; and disease management information was shared with growers, commodity groups and industry organizations through publications and presentations at conferences, field days, and extension schools delivered at more than 100 venues in 24 states. The CucCAP projects were carried out through joint efforts among 26 university and USDA coinvestigators and their research groups along with valued input and assistance from NPGS cucurbit crop curators, seed industry collaborators, cucurbit growers, external evaluators, and international collaborators. In addition to the specific genomic, breeding, and disease management outputs, the CucCAP projects have had broader impacts including use of the new genomic tools to provide insights into cucurbit biology, synergistic effects resulting from a more cohesive cucurbit community, and scientific training of a cadre of students and postdoctoral researchers.

Southern blight of sunchoke (Helianthus tuberosus) is caused by the soilborne fungus Agroathelia rolfsii. Symptoms and signs include wilting, stem lesions, white mycelium and brown sclerotia at the base of the plant, and plant death. This study evaluated the efficacy of three conventional fungicides to prevent and treat southern blight on sunchoke. The trial was conducted in 2024 in Charleston, SC, on sunchoke (or Jerusalem artichoke). The results will help growers choose fungicides to manage this disease.

Pseudomonas cannabina pv. alisalensis is a gram-negative bacterium that causes bacterial leaf blight in Brassica crops, an important disease that could bring severe damage to the host plants. The aim of this study was to develop a tool that can reliably and accurately quantify P. cannabina pv. alisalensis and distinguish it from other closely related bacterial pathogens. Two species and six pathovars of Pseudomonas were tested: three pathovars, P. syringae pv. coriandricola, P. syringae pv. philadelphi, and P. syringae strains from Vicia faba, were found or confirmed to be members of P. cannabina based on the multilocus sequence analysis and repetitive element sequence-based PCR results. The quantitative PCR (qPCR) assay was evaluated for specificity and examined for detection limit in pure bacterial cells and bacteria-spiked plant samples. The assay was applied in monitoring the quantities of the P. cannabina pv. alisalensis DNA over time in inoculated turnip green leaves. The newly developed qPCR assay detected the target DNA in P. cannabina pv. alisalensis suspension as low as 100 CFU/ml and did not detect any of the nontarget bacteria. The qPCR assay detected P. cannabina pv. alisalensis in all the inoculated samples at least 5 days before the symptoms became visible; bacterial quantity increased significantly in the first 3 days after inoculation but slowed down afterward. The new qPCR assay for P. cannabina pv. alisalensis detection will facilitate early detection and disease diagnosis, assist research to provide epidemiological insights for the pathogen, and guide implementation of strategies to manage disease and prevent its spread.

Curly kale (Brassica oleracea var. sabellica), lacinato kale (B. oleracea var. palmifolia), Portuguese kale (B. oleracea var. costata), and Siberian kale (Brassica napus var. pabularia) are produced with conventional and organic practices in the southeastern United States. The foliar disease black spot, caused by the fungi Alternaria brassicicola and Alternaria japonica, may reduce yields of curly kale, but its effects on other kale types are unknown. The objectives of this study were to determine which kale cultivars had the lowest percentage of symptomatic leaves (disease incidence) and greatest yield of healthy leaves when grown with conventional and organic practices in fall and spring. Single-row plots of 14 kale cultivars were inoculated on the ends with one Alternaria sp., which then spread to noninoculated plants in the center of the plot. Season, production, pathogen species, harvest, and inoculation affected cultivar performance; season had the largest effect. In general, Portuguese kale was the most susceptible kale type, followed by curly kale. Black spot incidence was greater at the second harvest of cropped plants than at the first harvest. Siberian kales yielded more than curly and lacinato kales, although green curly kale cultivar Winterbor had yields similar to the best-yielding Siberian kales.

Gummy stem blight (GSB), caused primarily by the fungus Stagonosporopsis citrulli in the Southeastern United States, affects cucurbits and is particularly destructive on watermelon. Previous epidemiological models of GSB constructed for greenhouse cucumber showed leaf wetness and temperature were the primary and secondary environmental factors, respectively, that explained epidemic progress. The objective of this study was to construct a model that predicted GSB severity on field-grown watermelon based on environmental factors. Disease and weather data from six fungicide experiments in Charleston, South Carolina, in the spring and fall of 1997 and the fall seasons of 2017, 2018, 2019, and 2022 were used as inputs. Fungicide treatments were grouped into nonsprayed, protectant (chlorothalonil and mancozeb), and GSB-specific (cyprodinil, difenoconazole, and fludioxonil) applications. Cumulative hours of leaf wetness were the primary explanatory variable that modeled the increase in proportion GSB severity ≥2% across all epidemics. Incorporation of temperature or other environmental variables did not improve the model. Fit of the overall model was evaluated with k-fold cross-validation, where individual experiments were each excluded from the model-fitting process. Slopes of predicted disease progress curves were lowered significantly compared with the nonsprayed treatments by applications of protectant fungicides. Applying GSB-specific fungicides alternated with chlorothalonil further reduced slope values. The model successfully predicted progress of GSB epidemics under different weather patterns and fungicide applications.

Over the past two decades, significant changes in the population structure of Pseudoperonospora cubensis have been reported worldwide. These changes have been associated with, among other things, severe epidemics of cucurbit downy mildew that are now much more destructive particularly on cucumber, than has previously been reported. Host specificity has complicated disease control as host resistance and fungicides that were previously effective in controlling the disease have become less effective. In response to this resurgence, significant research efforts have been made to better understand disease epidemiology, pathogen biology and host resistance, to generate information to improve disease management. Oospores have been reported under natural field settings in the United States, however, uncertainty remains regarding their role as a source of inoculum for initial disease outbreaks in northern latitudes that experience hard frost. Further, recent work indicates that the initial source of inoculum in the continental United States is southern Florida and along the edge of the Gulf of Mexico. Network analysis of disease outbreaks has identified key locations in the eastern United States that could be critical for disease monitoring in an effort to limit epidemic spread during the growing season. Lineage-specific biosurveillance of P. cubensis using spore traps complements existing disease monitoring efforts and is providing opportunities for precision management by determining cucurbit crops at risk of infection during the season. This review summarizes the substantial progress that has been made in understanding the biology of P. cubensis, disease epidemiology and control, which could inform better the management of cucurbit downy mildew.

Endemic pathogens continue to pose threats of recurring outbreaks, especially in agricultural settings. How these outbreaks unfold and what drives the variability in disease epidemics is less understood. We addressed this question in the Xanthomonas-tomato pathosystem by developing an integrated approach that linked the within-field quantitative signature of local pathogen diversity to climatic conditions to explain variable bacterial disease epidemics across fields. Using strain-resolved metagenomics, we found that pathogen heterogeneity with multiple co-occurring lineages is common. Higher disease severity was associated with higher pathogen diversity. Considering these observations, we used response-specific regression models to investigate the role of environmental variables in driving differences in disease and strain dynamics. Abrupt and frequent changes in environmental factors explained the variability of disease severity. We observed variable lineage dynamics across fields, but at least two lineages with divergent, climate-dependent fitness strategies coexisted throughout the growing season without either of them taking the lead. We further profiled the dynamics of single-nucleotide polymorphism variants in the pathogen population and observed that some alleles are temporarily favoured by specific climatic conditions encountered throughout the growing season, leading to oscillating seasonal patterns of allelic frequencies. These alleles can be referred to as seasonal alleles. Overall, our study revealed that the seasonal fluctuations in pathogen strain composition, diversity and climate-influenced pathogen fitness play a significant role in shaping the severity and variability of bacterial spot disease outbreaks.

In South Carolina, the disease black spot on kale is caused by the fungi Alternaria brassicicola and A. japonica. Because all kale cultivars are presumed to be susceptible, organic producers may apply biofungicides to prevent or manage black spot. Microbial and biochemical biofungicides were tested in the greenhouse (12 products) and the field (10 products) against black spot caused by both Alternaria spp. on organically produced kale. Thereafter, three biofungicides (copper hydroxide, potassium silicate, and Reynoutria sachalinensis extract) were tested in the field on three kale cultivars. Although several biofungicides reduced black spot in the greenhouse compared with the water-treated control, no biofungicides did so in the field even though they were applied preventatively before plants were inoculated. Biofungicides also did not increase the weight of healthy leaves compared with the water-treated control in any field experiment. Conversely, two biofungicides that increased the severity and incidence of black spot in the greenhouse, B. amyloliquefaciens F727 and potassium bicarbonate, reduced weights of healthy leaves in the field. On average, curly kale cultivar Winterbor had fewer diseased leaves than curly kale cultivar Darkibor, and lacinato kale cultivar Toscano had fewer diseased leaves than curly kale. Winterbor also consistently produced greater healthy leaf weight than Darkibor. Biopesticides are not recommended against black spot on organic kale. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Recurring outbreaks caused by endemic pathogens present a significant challenge to agricultural systems. Thus, understanding the risk factors involved in fueling the continued outbreaks and pathogen evolution is a priority. Isolate genome sequencing efforts have largely guided our past understanding of the pathogen population structure. However, this approach can overlook the importance of co-occurring pathogenic genera, species, or even lineages of the same pathogenic species in shaping disease dynamics. Here, we aimed to monitor pathogen population dynamics at a finer resolution, tap into the genetic variation existing and emerging within and across fields, and understand the determinants of this diversity in the Xanthomonas -tomato pathosystem. Using strain-resolved metagenomics, we found that pathogen heterogeneity with multiple co-occurring lineages is common, although accompanied by differential lineage dynamics and that higher disease severity is associated with higher pathogen diversity. Considering these observations, we used response-specific regression models to investigate the roles of environmental variables on driving these differential dynamics. We find that climatic fluctuations can modify the endemic disease risk and that the pathogen adapts to these climatic shifts by maintaining diversity of co-occurring lineages, each with a varying fitness contribution. We identified signatures of seasonal adaptation by monitoring genome-wide allele frequencies in pathogen. The observation of seasonal oscillations in allelic frequencies depicted evidence for fluctuating selection contributing to the patterns of genetic variation. We also identified positively selected loci under parallel evolution such as type VI secretion system genes and TonB-dependent receptors, which may explain the nature of selection pressures experienced by the pathogen. The findings from this study reveal fitness strategies adopted by endemic pathogens and how pathogens can evolve under the changing climate. Our high-resolution combinatorial approach exploiting a series of sequence data and metadata types and analysis tools, is general enough to finely investigate eco-evolutionary dynamics of pathogens at large scales in diverse case-studies concerning plant health, but also animal and human health. ### Competing Interest Statement The authors have declared no competing interest.

Cercospora leaf spot, caused primarily by Cercospora beticola, is common on red beet wherever this vegetable crop is grown. The effectiveness of a conventional (propiconazole rotated with azoxystrobin) and an organic biofungicide (Bacillus amyloliquefaciens mixed with copper octanoate) program were tested on four cultivars of beet that differed in susceptibility. Three inoculum densities were established by inoculating a 1-m portion of one row, allowing conidia to splash to the adjacent row, and not inoculating the remainer of the plot. Foliar severity was reduced by both fungicide programs compared to the water-treated control, but the conventional fungicides were more effective in the high inoculum area than the organic fungicides. The conventional fungicides also increased the fresh weight of healthy leaves compared to the water control, but the organic fungicides did not differ from the other two treatments. All cultivars except the most resistant one, Bull's Blood, had greater healthy weights in 2022 when the inoculum density was lower than in 2021. Cultivars sorted in the same order of susceptibility regardless of fungicide program. In all treatments, mean weight of diseased individual leaves was greater than healthy leaves. Partial cultivar resistance and fungicides or biofungicides had additive effects for integrated management of Cercospora leaf spot on red beet.

Alternaria brassicicola was found on pieces of chopped, bagged kale held 1 week beyond the typical postharvest storage period. Three of 11 Alternaria isolates were identified as A. brassicicola based on species-specific primers and multilocus genotyping with the translation elongation factor 1-alpha, RNA polymerase second largest subunit, and glyceraldehyde-3-phosphate dehydrogenase gene regions. Four isolates of A. alternata and four isolates comprising two unidentified species also were found. A. brassicicola also was found in a production field on the same farm. In the greenhouse, only A. brassicicola isolates caused disease on inoculated kale plants. As previously reported, A. brassicicola isolates had larger colony diameters on semiselective Chen and Wu medium than the nonpathogenic isolates. Black spot caused by A. brassicicola on kale leaves in the field can lead to black spot on harvested kale.

In September 2023, broccoli (Brassica oleracea var. italica) 'Sweet Bunch' plants on an organic farm in Buncombe County, North Carolina (NC), displayed symptoms of Alternaria leaf spot. Disease affected 10 to 20% of leaf area on all (approximately 30) plants. Lesions were dark brown with chlorotic halos, irregular in shape, and ≤3 cm in diameter. Leaf samples were incubated in a humidity chamber for 24 h, and the pathogen was putatively identified as Alternaria brassicae based on conidial morphology (Rimmer et al. 2007; Supplemental Fig. 1). Leaf pieces (2 x 2 mm) spanning lesion edges were surface-disinfested (1% sodium hypochlorite solution) for 1 min, rinsed in sterile distilled water, embedded in potato dextrose agar, and incubated at 22°C with a 12-h photoperiod. A pure culture was obtained by transferring a hyphal tip onto 20% V8 juice agar and incubated as above. After 10 d, colonies consisted of concentric zones of white to brown mycelia with white, aerial mycelia. Within 7 d, conidia measuring 80 to 150 µm long with 0 to 3 longitudinal septa, 6 to 15 transverse septa, and a long beak were observed, and the isolate was putatively identified as A. brassicae (Rimmer et al. 2007). To confirm identification, DNA was extracted from mycelia and subjected to PCR using primers to amplify a portion of the internal transcribed spacer of rDNA (ITS: ITS1/ITS4) (White et al. 1990), the transcription elongation factor-1 (tef1: EF1-728F/EF1-986R) (Carbone and Kohn 1999), and the glyceraldehyde-3-phosphate dehydrogenase gene (GAPDH: gpd1/gpd2) (Berbee et al. 1999). Amplicons were sequenced at Eton Bioscience (Durham, NC) and subjected to BLAST analysis in NCBI GenBank. Sequences matched (99.5 to 100% identity) A. brassicae CBS 116528 accessions KC584185 (ITS), KC584641 (tef1), and KC584102 (GAPDH) (Woudenberg et al. 2013). All sequences were deposited in NCBI GenBank (accessions PP584506, PP584507, PP584508). To confirm pathogenicity on broccoli and kale (B. oleracea var. sabellica), 5-week-old plants of broccoli 'Sweet Bunch', 'Eastern Crown', and 'Green Magic' and kale 'Winterbor', 'Darkibor', and 'Oldenbor' grown in 10-cm-diameter pots were separated by crop type and arranged in four randomized complete blocks by cultivar. Each block contained single-plant replicates of each cultivar that were either inoculated or non-inoculated. Conidia of A. brassicae obtained from 10-d-old cultures (3.5 x 103 conidia/ml) were sprayed onto each inoculated plant until run-off. Non-inoculated plants were sprayed with distilled water. Plants were incubated in a humidity chamber alternated with ambient greenhouse conditions every 48 h for 10 d, with average greenhouse temperatures ranging from 15 to 28°C. The experiment was conducted twice. Dark brown to gray lesions measuring 1 to 3 mm in diameter were observed on leaves of all inoculated plants within 5 d of inoculation (Supplemental Fig. 2), and non-inoculated plants remained healthy. On broccoli plants, lesions expanded in concentric rings, and sporulation of the pathogen was observed on leaf tissue and petioles 10 d after inoculation. Lesions remained small (< 3 mm) on kale plants, and sporulation was not observed. Alternaria brassicae was re-isolated from leaf tissue of all inoculated cultivars using methods described above. Pathogen identity was confirmed via colony and conidial morphology. The larger impact of A. brassicae on brassicas is unknown, but finding this less common Alternaria species in the eastern United States could have implications for host resistance development and fungicide efficacy (Nieto-Lopez et al. 2023).

Specialty eggplants ( Solanum melongena L.), cultivars with fruit shapes, sizes, and colors different from the typical teardrop-shaped, dark purple eggplant fruit, are an underproduced vegetable commodity in the southeastern United States. Seven cultivars representing seven different fruit types were grown in Charleston, SC, USA, in Spring and Fall 2018 and 2019 to assess cultivar productivity and net return. Despite year-to-year variability, Hansel (Chinese type), Millionaire (Japanese type), and Gretel (white fruit) generally had greater weights of both marketable (US Fancy and No. 1 fruit) and edible (US Fancy, No. 1 and No. 2) fruit than Fairy Tale (Sicilian type) and Patio Baby (Indian type), whereas the globe-fruited cultivars Black Beauty (heirloom) and Rosa Bianca (Italian type), had intermediate yields. Yields of plants after ratooning in the fall were lower than in the spring before ratooning. Prices per carton paid by local food hubs for US Fancy, No. 1, and No. 2 fruit were two to three times greater than wholesale terminal market prices. Nevertheless, fruit weights were a greater determinant of net returns than prices were. Growers in the southeastern coastal plain can maximize net returns from specialty eggplant crops by choosing cultivars that produce high fruit weights.

Cucurbit downy mildew, caused by Pseudoperonospora cubensis, is an important disease affecting cucurbits worldwide. Chemical control is an effective method for disease control but P. cubensis has a high risk for developing resistance to fungicides. Alternating fungicides with different modes of action is recommended to avoid an increase of resistant subpopulations. Thus, this study was conducted to establish shifts in the sensitivity profiles of P. cubensis isolates during the growing season, wherein chlorothalonil was applied in alternation with either cymoxanil, fluopicolide, or propamocarb in field experiments conducted from 2018 to 2020 at Rocky Mount, NC and in 2018 and 2020 at Charleston, SC. The sensitivity of baseline isolates sampled early in the season or exposed isolates sampled late in the season to these single-site fungicides was determined using a detached-leaf assay, where tested isolates were classified as sensitive or resistant based on the relative disease severity. Based on the Kruskal-Wallis test, the distribution profile of relative disease severity among baseline and exposed isolates was significantly different where chlorothalonil was alternated with fluopicolide (χ 2 = 10.82; P = 0.001) but not with cymoxanil (χ 2 = 1.39; P = 0.238) or propamocarb (χ 2 = 2.37; P = 0.412). Although there was a directional selection toward resistance for isolates sampled from plots that were treated with fluopicolide or propamocarb alternated with chlorothalonil during a growing season, a significant shift in fungicide sensitivity distribution based on combined data were observed for fluopicolide (χ 2 = 8.25; P = 0.004) but not propamocarb (χ 2 = 1.05; P = 0.461). Baseline and exposed isolates sampled from the cymoxanil-treated plots were all resistant to this fungicide and there was no significant shift in their fungicide sensitivity profile during a growing season (χ 2 = 0.06; P = 1.000). These results indicate that a shift toward reduced sensitivity in P. cubensis can occur during a growing season and the efficacy of fluopicolide is likely to decrease as the frequency of the less sensitive subpopulations increases during a production season. The resultant effect on disease severity and selection of an insensitive subpopulation may accelerate the development of resistance to propamocarb in the southeastern United States.