Response of peanuts (Arachis hypogaea) to weather-based fungicide advisory sprays

Abstract Field studies were conducted in 2001 and 2002 near Yoakum, Texas, to determine the effect of advisory-based fungicide sprays on foliar and soil-borne disease development and peanut yield compared with fungicide sprays based on a calendar schedule. Chlorothalonil applied on a regular schedule seven times during the growing season was compared with a chlorothalonil/tebucanozole combination and advisory sprays of azoxystrobin, pyraclostrobin, and tebucanozole. Three advisory sprays were applied in both years with chlorothalonil applied at 40 and 110 days after application (DAP) and azoxystrobin, pyraclostrobin, or tebucanozole at 88 DAP in 2001, while in 2002, azoxystrobin, pyraclostrobin, or tebucanozole were applied 39 and 77 DAP followed by chlorothalonil applied 101 DAP. The chlorothalonil/tebuconazole combination consisted of chlorothalonil applied 59 and 74 DAP, followed by tebuconazole applied 74, 89, 104, and 118 DAP with a final chlorothalonil application 132 DAP. All fungicide sprays reduced foliar and soil-borne disease development when compared with the untreated check. No difference in foliar or soil-borne disease development or peanut yield was noted between chlorothalonil alone or tebucanozole applied on a calendar spray schedule and azoxystrobin, pyraclostrobin, or tebucanozole applied by advisory sprays. Peanut yield response reflected the improved disease control with fungicides. All fungicides improved peanut yield over the untreated check by at least 25% in 2001 and more than 70% in 2002.