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Evaluation of Criteria for the Utilization of Peanut Leafspot Advisories in Virginia. P. M. Phipps, Associate professor of plant pathology, Tidewater Research and Continuing Education Center, Suffolk, VA 23437; N. L. Powell, associate professor of agronomy, Virginia Polytechnic Institute and State University, Blacksburg 24061. Phytopathology 74:1189-1193. Accepted for publication 1 May 1984. Copyright 1984 The American Phytopathological Society. DOI: 10.1094/Phyto-74-1189.

The utility of peanut leafspot advisories developed by a computerized agro-environmental monitoring system was assessed in field trials from 1979 to 1982. The total number of fungicide applications according to leafspot advisories averaged 4.25 fewer per season than applications on a conventional, 14-day schedule. Leafspot incidence was generally greater in plots sprayed according to advisories, but peanut yields did not differ significantly from yields where the 14-day schedule was used. Both spray programs suppressed leafspot disease and improved yield in comparisons to untreated controls. Fungicide selection, delays in application, and cultivar susceptibility were found to affect the degree of leafspot control; but none of these factors precluded utilization of leafspot advisories for prevention of losses in crop yield or value. Rainfall immediately following fungicide application was believed to cause some reduction in performance of fungicides applied according to leafspot advisories. Leafspot advisories have been issued daily in Virginia from 10 June through 25 September since 1981. Increasing numbers of growers are utilizing these advisories as an integral part of strategies for leafspot control.

Additional keywords: groundnut, Arachis hypogaea, early leafspot, Cercospora arachidicola, late leafspot, Cercosporidium personatum.