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Stemphylium leaf spot, caused by Stemphylium vesicarium, and white rust, caused by Albugo occidentalis, can cause significant losses in spinach production. Management of these foliar diseases of spinach has become increasingly challenging with the development of fungicide resistance in some pathogen populations, high planting density and overhead irrigation used for baby leaf spinach production, and the fact that >60% of fresh market spinach production in the United States is certified organic. To identify spinach cultivars with resistance to Stemphylium leaf spot and white rust, a field trial was performed near Crystal City, TX, USA, in 2021 (79 cultivars), 2022 (87 cultivars), and 2023 (63 cultivars). Each year, the plants were inoculated with S. vesicarium and rated for disease severity. Plants were also rated for white rust severity that resulted from natural infection during the 2021 and the 2022 trials. During each trial, 11% to 27% of the cultivars were identified as resistant to Stemphylium leaf spot, and another 29% to 48% had moderately resistant reactions. In contrast, only 5 of 79 cultivars (6%) in the 2021 trial did not develop symptoms of white rust, and all 87 cultivars evaluated in the 2022 trial had symptoms of white rust. Although there was no significant correlation between mean Stemphylium leaf spot ratings and mean white rust ratings during these trials, the cultivars Colusa, Kodiak, PV-1569, and PV-1664 displayed resistant or moderately resistant responses to both diseases in at least two trials. Therefore, processing and fresh market spinach growers have resistant cultivars from which to select to reduce the economic impacts of Stemphylium leaf spot and white rust. [ABSTRACT FROM AUTHOR]

The landscape of scientific publishing is experiencing a transformative shift toward open access, a paradigm that mandates the availability of research outputs such as data, code, materials, and publications. Open access provides increased reproducibility and allows for reuse of these resources. This article provides guidance for best publishing practices of scientific research, data, and associated resources, including code, in The American Phytopathological Society journals. Key areas such as diagnostic assays, experimental design, data sharing, and code deposition are explored in detail. This guidance aligns with that observed by other leading journals. We hope the information assembled in this paper will raise awareness of best practices and enable greater appraisal of the true effects of biological phenomena in plant pathology. [ABSTRACT FROM AUTHOR]

Stemphylium leaf spot of spinach, caused by Stemphylium beticola and S. vesicarium , is a disease of economic importance in fresh market, processing, and seed production. There have been increasing reports of difficulty managing the disease in the southern United States using fungicides in Fungicide Resistance Action Committee (FRAC) group 11. Isolates of S. beticola and S. vesicarium obtained from spinach leaves and seed from 2001 to 2020 were screened for resistance to azoxystrobin and pyraclostrobin in vitro, in vivo, and using PCR assays to detect mutations in cytochrome b associated with resistance in other fungi (F129L, G137R, and G143A). EC 50 values for mycelial growth and conidial germination of S. vesicarium isolates in vitro were significantly less (mean of 0.35 μg/ml) than that of S. vesicarium (mean of 14.17 μg/ml) with both fungicides. All isolates were slightly more sensitive to pyraclostrobin than azoxystrobin in both assays. In vivo assays of plants inoculated with the isolates of S. vesicarium demonstrated poor efficacy of fungicides with each of the two active ingredients. Only the G143A mutation was detected in all spinach isolates of S. vesicarium , including an isolate of S. vesicarium collected in 2003 and 82.9% of isolates from spinach seed lots harvested from crops grown in or after 2017 in Europe, New Zealand, and the United States. The FRAC 11 mutations were not detected in any isolates of S. beticola . The in vitro, in vivo, and DNA mutation assays suggest FRAC group 11 fungicide resistance is widespread in spinach isolates of S. vesicarium but not S. beticola., Competing Interests: The author(s) declare no conflict of interest.