Control of Early and Late Leafspot on Two Peanut Cultivars1

Abstract

Abstract The effectiveness of four fungicides for control of Cercospora arachidicola Hori (CA) and Cercosporidium personatum (Berk and Curt.) Deighton (CP) on Arachis hypogaea L. ‘Florunner’ and ‘Early Bunch’ was evaluated in 1978 and 1979. Chlorothalonil (3.5 liters/ha) + flowable sulfur on a 10-day schedule (T1) gave the best control of both leafspots. Chlorothalonil alone (2.3 liters/ha) on a 14-day schedule (T2) provided better disease control and higher pod yields than three other fungicide treatments on both cultivars in 1979. With reduced disease pressure in 1980, triphenytin hydroxide + flowable sulfur and mancozeb + flowable sulfur were almost as effective as T1 and T2 in maintaining high pod yield on Florunner. Yields were significantly less both years on Early Bunch for all treatments other than T1 and T2. The incidence of CA leafspot was low both years and CP was the predominant leafspot pathogen. Significantly higher numbers of CP lesions were observed on Early Bunch than on Florunner at 70 and 90 days after planting (DAP) in 1979 and at 110 DAP in 1980. Numbers of CA lesions on the two cultivars were not significantly different. Average pod yields across fungicide treatments of the two cultivars were not significantly different in 1979 or 1980. Differences in disease levels and pod yields were greater among fungicide treatments than between cultivars.