Effect of Timing of Foliar Fungicides on Wheat Disease Control and Yield Increases. M. D. Dannenberg, Graduate Research Assistant, Department of Plant Pathology, Kansas State University, Manhattan 66506. M. G. Eversmeyer, and C. L. Kramer. Research Plant Pathologist, USDA-ARS, Department of Plant Pathology, and Professor, Division of Biology, Kansas State University, Manhattan 66506. Plant Dis. 73:227-229. Accepted for publication 30 October 1988. 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, 1989. DOI: 10.1094/PD-73-0227.

Control of foliar pathogens of winter wheat (Triticum aestivum) cultivars Arkan and Newton at several growth stages by application of triadimefon foliar sprays was observed in the 1985 and 1986 crop years. Single sprays of triadimefon on Newton at early dough and heading growth stages resulted in yield increases of 47 and 68%, respectively, in 1985 and of 24 and 39%, respectively, in 1986. Yield increases for Arkan with fungicide application at early dough and heading growth stages were 3 and 11%, respectively. Area under disease progress curve (AUDPC) (r = –0.79) and percent severity (r = –0.81) of leaf rust were negatively correlated with yield, whereas AUDPC (r = 0.53) and severity (r = 0.61) of leaf rust were positively correlated with percent yield increase. AUDPCs of Septoria leaf blotch (r = –0.60) and tan spot (r = –0.85) were also negatively correlated with yield. However, no significant effect of foliar fungicide treatment on control of either Septoria leaf blotch or tan spot was detected by Waller-Duncan’s multiple range test (P = 0.05).