Evaluation of Fungicides Applied After Infection for Control of Plasmopara viticola on Grapevine. T. Wicks, South Australian Department of Agriculture, Box 1671, G.P.O., Adelaide, South Australia 5001. T. C. Lee, Adelaide Botanic Garden, North Terrace, Adelaide 5000. Plant Dis. 66:839-841. Accepted for publication 9 December 1981. Copyright 1982 American Phytopathological Society. DOI: 10.1094/PD-66-839.

Sporulation of Plasmopara viticola was inhibited when tissue-cultured grapevine shoots were dipped in one-quarter the recommended rate of either metalaxyl, cyprofuram, phosethyl aluminum, milfuram, or cymoxanil 3 days after inoculation. Metalaxyl, cyprofuram, and phosethyl aluminum almost completely inhibited sporangial production when applied to grape leaves in the field 4 days after inoculation. Cymoxanil and milfuram both inhibited sporulation in the field but not to the same extent as the other systemic fungicides. The protectant fungicides mancozeb, copper oxychloride, and folpet did not inhibit sporulation. Metalaxyl and cyprofuram were the most effective fungicides to suppress sporulation from lesions sprayed 17 days after natural infection and to reduce germination of these sporangia.

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