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Disease Control and Pest Management

Efficacy of Benomyl for Controlling Septoria Brown Spot of Soybeans. J. K. Pataky, Graduate research assistant, Department of Plant Pathology, University of Illinois, Urbana 61801, Present address of senior author: Department of Plant Pathology, North Carolina State University, Raleigh 27650; S. M. Lim, associate professor and research plant pathologist, Agricultural Research, Science and Education Administration, U.S. Department of Agriculture, Urbana 61801. Phytopathology 71:438-442. Accepted for publication 17 September 1980. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1981. DOI: 10.1094/Phyto-71-438.

The effects of benomyl applied at three reproductive growth stages on Septoria brown spot of soybean were evaluated in the field for 2 yr. Apparent brown spot infection rates were lowered in plots of inoculated soybeans following benomyl sprays at the R1, R3, and R6 soybean growth stages. Brown spot was less severe when any schedule of benomyl applications included a spray at R3 or when applications were made at both R1 and R6. Brown spot severity at R7 and area under the disease progress curve (AUDPC) were highest for unprotected-inoculated plants, naturally infected plants, and plants that received a single spray at R1 or at R6. Reduction of brown spot during early and midreproductive stages may increase yields when brown spot would otherwise be severe and when potential yields are high.

Additional keywords: disease control, Glycine max, Septoria glycines, disease losses.