VIEW ARTICLE

Ecology and Epidemiology

Cultivar, Environment, and Fungicide Effects on Foliar Disease Losses in Soybeans. P. A. Backman, Departments of Botany and Microbiology, Auburn University Agricultural Experiment Station, Auburn, AL 36830; R. Rodriguez-Kabana(2), J. M. Hammond(3), and D. L. Thurlow(4). (2)(3)Departments of Botany and Microbiology, Auburn University Agricultural Experiment Station, Auburn, AL 36830; (4)Agronomy and Soils, Auburn University Agricultural Experiment Station, Auburn, AL 36830. Phytopathology 69:562-564. Accepted for publication 13 November 1978. Copyright 1979 The American Phytopathological Society. DOI: 10.1094/Phyto-69-562.

In 33 replicated soybean tests conducted throughout Alabama, yield of early- and late-maturing cultivars increased an average of 15.3 and 11.0%, respectively, if conditions favorable for infection by foliar pathogens occurred (>5 wet days between bloom and pod fill) and benomyl was applied. If weather was dry (<5 wet days) yield increases attributable to benomyl were 1% or less. Other tests, with planting dates staggered so plants of each cultivar bloomed at the same time, were used for critical comparisons of cultivar susceptibility. In order of yield reduction potential, the principal pathogens were: Colletotrichum dematium f. truncata, Septoria glycines, Cercospora sojina, and Diaporthe phaseolorum var. sojae. Evaluation of three fungicides for control of these pathogens indicated that benomyl was more effective than fentin hydroxide (FTH) against S. glycines, and slightly less effective than FTH against C. dematium f. truncata. Thiabendazole was less effective than the other products except for control of C. sojina.