New Uses of Fungicides in Soybeans

New Uses of Fungicides in Soybean

Historically, fungicide use on soybean has occurred mainly in the southern United States, especially in seed production fields. In Kentucky, few soybean fields have been treated with foliar fungicides since the late 1970’s. In 2002, Syngenta Crop Protection, Inc. began testing a combination of Quadris (a strobilurin fungicide) and Warrior (a synthetic pyrethroid insecticide), applied as a “preventative treatment”, at early pod formation in grower fields in Kentucky and southern Indiana. Results across 13 locations indicated an average yield increase of 6.8 bu/ac (range 1-14 bu). These encouraging data, prompted Syngenta to offer a “guarantee program” to some soybean producers in 2003. This program resulted in about 30,000 acres of soybean being treated with Quadris (6.2 fl oz/ac) + Warrior (2.56 fl oz/ac) in Kentucky during 2003. Also during 2003, the University of Kentucky began testing the Quadris + Warrior combination, as well as the individual pesticides. Yield results from two small plot experiments and seven strip plot tests in grower fields were variable, but the tendency was towards higher yields (3-8 bu/ac) where Quadris + Warrior was applied. Yield data from 51 additional grower fields showed a similar trend, with an average 4.6 bu/ac more being harvested from treated soybean than non-treated soybean (range 0-12.1 bu/ac). In three tests, neither Quadris nor Warrior applied alone significantly increased yields compared to non-treated check. When pest data were analyzed from both large and small plots, no insect or fungal pests seemed to account for the observed yield increases. Studies in 2004, which will be reported at the CCA Conference, dig deeper into possible pest and production factors that could be responsible for increased yields related to Quadris + Warrior use.

Don  HershmanExtension Plant Pathologist
University of Kentucky
dhershma@uky.edu

Biography:  Donald E. Hershman, a native of Pennsylvania, received a B.A. degree in biology from West Chester State College in 1978. He received M.S. and Ph.D. degrees in Plant Pathology from Rutgers University in 1981 and 1983, respectively. In 1984, he was appointed as an assistant Extension professor in the University of Kentucky Department of Plant Pathology, located at the Research and Education Center in Princeton, Kentucky. He is currently an Extension professor in the department. His Extension program centers on educational programs and applied research on diseases of soybean and wheat. Specific soybean research projects have involved soybean cyst nematode, sudden death syndrome, bean pod mottle virus, Phytophthora root and stem rot, and chemical control of various foliar, pod, and stem diseases. Wheat projects have focused primarily on chemical control of fungal diseases, especially Fusarium head blight. Over the past 20 years, Dr. Hershman has served numerous professional organizations in a variety of leadership positions. For the American Phytopathological Society, he has served as chair of the New Fungicide and Nematicide Data Commitee, as associate editor for Plant Disease, and as section editor for Fungicide and Nematicide Tests. Presently he is serving as a senior editor for Plant Disease and as a section editor for Biological and Cultural Control of Plant Diseases.