APS Homepage

Poster: Biology & Disease Mgmt: Chemical Control


Evaluation of host resistance and chemical control to manage white mold of soybean in Ohio
J. HUZAR NOVAKOWISKI (1), J. Huzar Novakowiski (1), J. Winger (1), P. Paul (1), A. Dorrance (1) (1) The Ohio State University, U.S.A.

White mold of soybean is caused by the fungus Sclerotinia sclerotiorum. In Ohio, localized outbreaks of the disease have occurred in each of the past seven years. Chemical control has had inconsistent results for disease management, especially when applied to cultivars with moderate levels of resistance. Therefore, in order to improve disease management recommendations, the objective of this study was to evaluate the efficacy of chemical control on soybean cultivars with different levels of resistance. The experiment was carried out in two fields in 2014 and five fields in 2015, all with a long history of the disease. Ten chemical treatments (untreated check, four fungicides applied at R1 or R1+R2 growth stages and one herbicide applied at R1), and two to four soybean cultivars were arranged in a split strip randomized block design with eight replications. Two fields had white mold in the untreated plots. There was significant interaction between chemical treatments and cultivars (P<0.05). Disease severity index (DSI) in the trials ranged from 2 to 41 in 2014 and from 14 to 44 in 2015. Applications of Endura fungicide and Phoenix herbicide significantly reduced DSI compared to the untreated control in both years. The cultivars with the highest disease resistance ratings had the lowest DSI and the highest yields. Thus, based on our results, growers should focus on soybean cultivars with the highest resistance ratings to manage white mold of soybean.