Dual Culture of Plasmopara viticola and Grapevine and Its Application to Systemic Fungicide Evaluation. T. C. Lee, Adelaide Botanic Garden, North Terrace, Adelaide 5000. T. Wicks, Department of Agriculture, Box 1671, G.P.O. Adelaide, South Australia 5001. Plant Dis. 66:308-310. Accepted for publication 3 June 1981. Copyright 1982 American Phytopathological Society. DOI: 10.1094/PD-66-308.

Successful dual cultures of Plasmopara viticola and grapevine (cvs. Cabernet Sauvignon and Cabernet Franc) were achieved by tissue culture techniques. A simple and rapid method of inoculation to produce large numbers of dual cultures for experiments is described. Following inoculation, sporangia were produced on leaves and stems after 5 days and leaf chlorosis appeared 7 days later. Viable sporangia have been maintained in culture for 12 wk, and regular subculture of grapevines and reinoculation with sporangia have maintained dual cultures for 9 mo. The dual cultures were used to demonstrate the systemic and curative properties of metalaxyl on grapevine downy mildew. Results suggested that the system may be used to screen fungicides or to compare these properties in various fungicides. The system could also be used to screen grape cultivars rapidly for resistance to P. viticola.

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