Enhancing Integrated Options to Better Manage Soybean White Mold using a Biological Fungicide
Waldron, J. Keith; Dillard, Helene; Bergstrom, Gary C.
Field studies were conducted in two commercial and one Cornell research farm soybean fields to evaluate the effect of the biological fungicide Contans® WG (SipCam) on white mold of soybeans caused by Sclerotinia sclerotiorum. Our highest criteria priority was for field selection was to have at least a few sclerotia observed on the soil surface. Unfortunately, sclerotia were difficult to find on any candidate fields. Given the difficulties in easily finding sclerotia on candidate fields, our experimental field selection became heavily weighted towards fields with a previous recent history of severe economic losses from white mold disease within the past three years. Each field selected for study met these criteria and was divided into two and randomly assigned a spring application of either Contans® WG at a 4 lb. / acre rate or left as an untreated control (UTC) plot. Contans® WG was applied by cooperators prior to planting soybeans according to label instructions after soil temperatures reached a minimum of 50 F. Fields were assessed for presence of white mold apothecia and level of disease incidence beginning at initiation of soybean bloom (approximately mid July) until harvest. The 2012 growing season in our western New York study locations was marked by below normal precipitation and drought conditions. The dry weather was not conducive disease development in any experimental field. Irrigation applications at the Cornell site also did not result in disease development. In our current study, numbers of apothecia and yields of soybeans in plots treated with Contans were not different from the untreated check (UTC). Unfortunately, without white mold being present in plots it was impossible to critically evaluate the effect of Contans on disease incidence under field conditions this season. Under suitable conditions soybean white mold disease can be devastating. When the disease is present control options are limited, efficacy of current management strategies are variable and there are implications for long term disease management. While these studies have not provided the data and insights we had hoped for, they did provide the opportunity to gain experience with use of this biological product, have stimulated additional interest in this area of research and have enhanced our outreach efforts on soybean disease education and management. Given the importance of environmental conditions and difficulties in obtaining significant disease under natural field conditions, it may be that future evaluations of this and other products for management of soybean white mold will necessarily rely on additional studies, producer field trials of various products, including new biocontrol materials and novel strategies compared to untreated checks. Clearly additional alternatives are needed to enhance an integrated management approach towards soybean white mold.
NYS IPM Type: Project Report
New York State Integrated Pest Management Program
Agricultural IPM; Field Crops; Soybeans