The Use of Film-forming Antitranspirants to Control Rose Blackspot Disease

Abstract

Five antitranspirant materials, a horticultural oil, the fungicide chlorothalonil, and an untreated control were applied to rose plots using one of four application schedules. After 12 weeks, treatments were evaluated for their effectiveness in control of blackspot. Disease (P=0.0022) and defoliation (P=0.0008) showed significant treatment differences, while vigor and flowering were unchanged. Two antitranspirants, Stressguard 0.05% applied every 2 weeks and NuFilm17 1% alternated with chlorothalonil around rain events, gave similar disease control to weekly chlorothalonil applications. One antitranspirant, Vapor Gard, 1 % alternated with chlorothalonil around rain events, gave similar defoliation control to weekly chlorothalonil applications. These results indicate that blackspot disease can be effectively managed with fewer applications of chlorothalonil.