Reduction of Root Rot Caused by Phytophthora cinnamomi in Grapevines by Chemical Treatments. P. G. Marais, Research Plant Pathologist, Viticultural and Oenological Research Institute, Private Bag X5026, 7600 Stellenbosch. M. J. Hattingh, Associate Professor, Department of Plant Pathology, University of Stellenbosch, 7600 Stellenbosch, Republic of South Africa. Plant Dis. 70:109-111. Accepted for publication 11 June 1985. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1986. DOI: 10.1094/PD-70-109.

In glasshouse and field trials, fosetyl A1 applied as a spray and metalaxyl applied as a soil drench significantly reduced Phytophthora cinnamomi root rot of 99 Richter grapevine rootstock. Application of methyl bromide, dazomet, or metalaxyl to infested nursery soil before planting significantly reduced root rot, but the pathogen became reestablished in the soil. To reduce the disease effectively in nurseries, chemical soil treatment should be followed by regular applications of appropriate fungicides to the growing vines.