Phomopsis Cane and Leaf Spot Disease of Grapevine: Effects of Chemical Treatments on Inoculum Level, Disease Severity, and Yield
- 1 January 1982
- journal article
- research article
- Published by Scientific Societies in Plant Disease
- Vol. 66 (1) , 794-797
- https://doi.org/10.1094/pd-66-794
Abstract
A commercial vineyard (V. vinifera cv. Tokay) located in Lodi, California [USA], was used for a 2-yr study of Phomopsis cane and leaf spot disease of grapevines. Fungal activity was monitored by periodically examining the ability of pycnidia to exude spores when hydrated. Pycnidial levels followed a seasonal pattern, with the maximum (15 active pycnidia/c2) being reached just prior to 100% budbreak. Of the 3 chemicals used to control Phomopsis viticola, dinoseb and sodium arsenite suppressed pycnidial activity whereas captan did not. The 3 chemicals reduced disease severity by different degrees. Pycnidial levels were highly correlated (P .ltoreq. 0.001) with disease and were used as a measure of inoculum. An increase in disease severity was associated with a reduction in the weight of the fruit per vine (r = - 0.511, P .ltoreq. 0.05).Keywords
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