Efficacy of Metalaxyl and Metalaxyl Tank Mixes in Controlling Albugo occidentalis and Peronospora effusa on Spinach (Spinacea oleracea). R. K. Jones, Plant Pathologist, Texas Agricultural Extension Service, Texas Agricultural Experiment Station, Uvalde 78801. F. J. Dainello, Research Horticulturist, Texas Agricultural Experiment Station, Uvalde 78801. Plant Dis. 67:405-407. Accepted for publication 15 September 1982. Copyright 1983 American Phytopathological Society. DOI: 10.1094/PD-67-405.

Foliar sprays of metalaxyl and ethylene bisdithiocarbamate (EBDC) effectively reduced percent infected leaves and yield loss of spinach attributed to Albugo occidentalis and Peronospora effusa. Chlorothalonil sprays were effective in reducing losses to A. occidentalis but were ineffective against P. effusa. A reduced-rate tank mix of metalaxyl plus EBDC was as effective in controlling both diseases as full rates of the individual compounds. A reduced-rate tank mix of metalaxyl plus chlorothalonil was as effective as the individual compounds in controlling A. occidentalis but was ineffective in controlling P. effusa. The implications of tank mixing metalaxyl on the development of resistant strains are discussed.

Keyword(s): blue mold, downy mildew, white rust.