Control of Cucumber Foliar Diseases, Fruit Rot, and Nematodes by Chemicals Applied Through Overhead Sprinkler Irrigation. Donald R. Sumner, Department of Plant Pathology, Coastal Plain Experiment Station, Tifton, GA 31794. Sharad C. Phatak and Doyle Smittle, Department of Horticulture, University of Georgia; and A. W. Johnson, Nematologist, and N. C. Glaze, Plant Physiologist, U.S. Department of Agriculture, Science and Education Administration, Coastal Plain Experiment Station, Tifton, GA 31794. Plant Dis. 65:401-404. . 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/PD-65-401.

Application of fungicides through irrigation water was compared with application by tractor-mounted boom or downdraft sprayers for control of foliar diseases on cucumber. Chlorothalonil applied through irrigation water and applied with tractor-mounted sprayers provided equal disease control in a resistant cultivar where gummy stem blight and target spot were the major diseases. In contrast, when an epidemic of downy mildew developed in a susceptible cultivar, chlorothalonil, mancozeb F, and mancozeb WP were more effective in lowering the infection rate and reducing disease severity when applied by ground sprayers than when applied through irrigation water. Control of root-knot nematodes with a nematicide (phenamiphos) reduced fruit rot and increased yield in plots sprayed with chlorothalonil, but foliar injury was so severe in unsprayed plots that nematode control was not beneficial.