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Lambert B. McCarty, Leon T. Lucas and Joseph M. DiPaola

Spring dead spot (SDS) [Gaeumannomyces graminis (Sacc.) von Arx & D. Olivier var. graminis Walker] is a serious disease of bermudagrass [Cynodon dactylon (L.) Pers.] throughout much of the southern United States and is believed to be at least partially influenced by the previous year's turfgrass management practices. Research was performed to: a) determine the efficacy of selected fungicide control measures; and b) determine the influence of N and K nutrient regimes on the expression of SDS symptoms in Tifway bermudagrass (C. dactylon x C. transvaalensis Burtt-Davy). Averaged over two sites in 2 years, a 72% reduction in SDS followed a fall application of benomyl at 12 kg·ha. Fenarimol applied at three rates (1.5, 2.3, and 3.0 kg·ha) on three fall dates reduced SDS by a combined average of 66%. A single application of propiconazole (2.5 kg·ha) reduced disease by an average of 56%. Application of N (98 kg·ha) in late fall increased SDS 128% in one test location. Application of potassium sulfate (269 kg K/ha) in late fall resulted in an average increase in SDS expression of 89% the following spring over all experiments. Turf managers with severe SDS should minimize heavy late-fall K applications and possibly use benomyl, fenarimol, or propiconazole for disease suppression. Chemical names used: α -(2-chlorophenyl)α -(4-chlorophenyl)-S-pyrimidinemethanol (fenarimol); [methyl 1(butylcarbamoyl)-2-benzimidazolecarbamate] (benomyl); 1-[[2-(2,4-dichlorophenyl)-4propyl-1,3-dioxolan-2-yl]methyl]--1H-1,2,4-triazole (propiconazole).