Effect of planting date and potato cultivar on powdery scab caused by Spongospora subterranea

Abstract

Powdery scab (PS) caused by Spongospora subterranea, causes lesions on potato tubers and root galling, resulting in significant yield losses. Disease development is affected by soil inoculum and environmental conditions, mainly temperature and soil moisture. A field trial with naturally infested soil was conducted to evaluate the effect of planting date on PS incidence and root galling, using 11 cultivars. Tubers of all tested cultivars had significantly lower levels of PS following the early winter planting dates (7- and 25-October), compared to late planting (15-November). No root galling was observed on plants sampled from the first two planting dates, whereas, in the late planting date, typical root galls were observed at different levels on all tested cultivars. To conclude, planting in fields with a history of PS in warm temperatures and using tolerant cultivars can reduce the risk of PS and considered as a part of disease management.