Rebecca Higgins, James R. Steadman
The development of common bean cultivars with partial resistance and/ or avoidance to white mold (WM) caused by Sclerotinia sclerotiorum would benefit producers by reducing yield loss and reducing input costs for fungicides. Our main objective in this study is to identify bean germplasm supplied by bean breeders from across the USA and Belgium with levels of partial resistance to WM. Breeders sent seed of 9 bean lines for field testing and 25 bean lines for greenhouse testing with putative sources of resistance to our laboratory. The seeds were divided in equal amounts for field (400g/line) and/or greenhouse (25 seeds/ line) tests and then sent to eight locations to be evaluated by standardized greenhouse and/or field screening methods. Three bean lines were included in both tests as controls: a good source of partial resistance G122, Bunsi with mostly field avoidance and susceptible GN Beryl. The use of multisite screening in the field was justified when only three sites had data. Weather was the primary factor in locations with field plots that did not report any data. There were eight lines with resistance higher than Beryl and five with resistance similar to the resistant G122 (Table 1).