Use of Weather-based Advisory Programs to Manage Peanut Foliar Diseases in South Texas

Abstract

Studies were conducted over a 2-year period at Yoakum, TX, using the Neogen EnviroCaster• equipped with models to time fungicide sprays for control of early leaf spot (Cercospora arachidicola S. Hori), late leaf spot [(Cercosporidium person­alum) (Berk. & M. A. Curtis) Deighton] and rust (Puccinia arachidis Speg.) of peanut. Models used were version 4.5 of the early leaf spot advisory and version 2.5 of the late leaf spot advisory. The EnviroCaster® is a computerized weather station which collects weather data that drives the algorithms (models) and produces interpretive output. Advisory programs were compared to a 14-d calendar program in field plots of Florunner peanut. In both years, the incidence of early leaf spot and rust was heavy, while late leaf spot incidence was moderate in unsprayed plots. The fungicides chlorothalonil and tebuconazole were applied according to each spray program to control disease. Plots managed by 14-d calendar program with chlorothalonil or tebuconazole had significantly lower incidence of leaf spot (P ≤ 0.05) than advisory programs each year. Plots managed by 14-d calendar program with chlorothalonil or tebuconazole had significantly lower incidence of leaf spot (P ≤ 0.05) than advisory programs each year. Plots receiving four sprays in 1991 and three sprays in 1992 with chlorothalonil according to the late leaf spot (LLS) advisory showed levels of rust that were not significantly higher than plots receiving eight sprays on the calendar schedule. Plots treated with four tebuconazole sprays according to the LLS advisory model had significantly higher levels of rust (P ≤ 0.05) than plots sprayed on a 14-d schedule or either of the early leaf spot (ELS) or combination early leaf spot/late leaf spot (ELS/LLS) advisories in 1991. Plots sprayed according to the ELS/LLS combination model in 1992 with tebuconazole had significantly less rust (P ≤ 0.05) than the calendar or the ELS or LLS advisories. Although results from both years show a higher disease incidence in advisory programs compared to the 14-d program, there were no significant differences in yield (P ≤ 0.05) among any of the programs. These results imply that the number of sprays can be reduced without sacrificing yield and the timing of sprays is important in managing foliar diseases in Texas.