Implementing a Management Program for Sclerotinia sclerotiorum in Snap Beans

Given the right environmental conditions, white mold (Sclerotinia sclerotiorum) can potentially infect 100 percent of the snap bean acreage in New York State. A black seedlike structure called a sclerotia resides in the soil as the overwintering/survival structure for Sclerotinia sclerotiorum, the causal agent of white mold. Part of the reason why white mold is such a problem in Western New York is because aside from snap beans many other commercial crops are hosts for Sclerotinia sclerotiorum, including dry beans, cabbage, potatoes, tomatoes, peppers, lettuce, vine crops, alfalfa, and soybeans. The main objective of this study was to evaluate Contans WG as a biological tool to manage white mold in snap beans and compare it with the industry standard Ronilan in an on-farm situation. Trials were set up in Genesee and Orleans Counties where growers applied Contans WG using their typical cultural practices at planting to a portion of the field. Contans WG reduced sclerotia populations over the course of the experiment from 0.2 to 0.0 sclerotia per liter of soil at one location but had no effect at the other (possibly due to Dual antagonism). Contans WG did not reduce white mold infection on the foliage. Ronilan reduced foliar incidence of white mold by 50 and 71%. The poorer control with Ronilan may be explained by the use of a low spray volume and poor penetration into the center of the canopy. Contans WG may reduce sclerotia populations in soil, but should not be used as a stand alone material for control of white mold