Control of White Rust of Spinach with Partial Resistance and Multiple Soil Applications of Metalaxyl Granules. Frank J. Dainello, Associate Professor, Department of Horticultural Sciences, Texas A&M University Agricultural Research and Extension Center, Uvalde, TX 78801. Mark C. Black, and Timothy E. Kunkel. Extension Plant Pathologist, Department of Plant Pathology and Microbiology, Texas A&M University Agricultural Research and Extension Center, Uvalde, TX 78801, and Agricultural Research Supervisor, Del Monte Foods, USA, Crystal City, TX 78839. Plant Dis. 74:913-916. Accepted for publication 19 March 1990. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/PD-74-0913.

Efficacy of zero, one, two, or three soil applications of metalaxyl fungicide for control of white rust disease of spinach (Spinacia oleracea), caused by Albugo occidentalis, was determined on a susceptible and a partially resistant cultivar. Metalaxyl on both cultivars delayed the development of initial white rust symptoms but did not reduce the rate of disease progress. The relative reduction of white rust from metalaxyl soil applications was greater on the susceptible cultivar than on the resistant cultivar. White rust was less severe on the untreated resistant cultivar than on the susceptible cultivar receiving three applications of metalaxyl.