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Influence of Tillage and Nitrogen Fertilizer on Rhizoctonia Root Rot (Bare Patch) of Winter Wheat. F. V. Pumphrey, Professor of Agronomy, Oregon State University, Hermiston Agricultural Research and Extension Center, Hermiston 97838. D. E. Wilkins, D. C. Hane, and R. W. Smiley. Agricultural Engineer, USDA-ARS, Columbia Plateau Conservation Research Center, Pendleton, OR 97801; Research Technician, Oregon State University, Hermiston Agricultural Research and Extension Center, Hermiston 97838; and Professor of Plant Pathology, Oregon State University, Columbia Basin Agricultural Research Center, Pendleton 97801. Plant Dis. 71:125-127. Accepted for publication 18 September 1986. 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, 1987. DOI: 10.1094/PD-71-0125.

Discovery of Rhizoctonia root rot (Rhizoctonia solani) in northeastern Oregon during 1984 led to studies of the impact of seed bed tillage and nitrogen fertilization on occurrence of the disease and a comparison of growth and yield of bare patch-affected and unaffected winter wheat plants. Seedbed preparation of moldboard plowing, subsurface tillage, paraplowing, and nontillage were applied to wheat following alfalfa and wheat following wheat rotations. Nitrogen fertilizer treatments of 1) no fertilizer, 2) 56 kg/ha at planting plus 168 kg/ha at late tillering, 3) 56 kg/ha at planting plus 224 kg/ha at late tillering, and 4) 168 kg/ha at late tillering were applied over the tillage treatments. Frequency of bare patch occurrence was inversely related to amount of soil disturbance in seedbed tillage. Level and timing of nitrogen fertilization had no impact on frequency of occurrence of patches. Grain and straw yields of visually affected plants were reduced by more than 50%, primarily by reduction in the number of heads. Growers practicing conservation tillage must remain alert to the potential for development of Rhizoctonia root rot; however, severity of this disease can be greatly reduced in infected fields by increased soil disturbance during tillage for seedbed preparation.