Control of Bottom Rot of Head Lettuce with Iprodione. S. E. R. Mahr, Department of Plant Pathology, University of Wisconsin, Madison 53706. W. R. Stevenson, and L. Sequeira, Department of Plant Pathology, University of Wisconsin, Madison 53706. Plant Dis. 70:506-509. Accepted for publication 17 December 1985. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-506.

Bottom rot of lettuce (caused by Rhizoctonia solani) commonly results in serious losses in Wisconsin because of a lack of effective, economical control measures. Field tests were conducted in 1982 and 1983 in commercial lettuce plantings to determine the efficacy of iprodione and other fungicides. Iprodione increased yield as much as 92% and decreased disease severity compared with untreated controls. Two applications with 2.3 kg/ha of an iprodione 50WP formulation directed at the bases of plants and over leaves 4 and 6 wk after seeding gave adequate control under most conditions. Iprodione was registered for use on commercial head lettuce in 1983.

Keyword(s): Lactuca sativa.