Use of Resistant Peanut Cultivars and Reduced Fungicide Inputs for Disease Management in Strip-Tillage and Conventional Tillage Systems

Abstract

Field experiments were conducted in 2000 and 2001 to determine the effects of the number of fungicide applications and resistant cultivars on early leaf spot (Cercospora arachidicola) of peanut (Arachis hypogaea) grown in strip-tillage versus conventional tillage. Split-plot experiments with four replications of cultivars and fungicide treatments were conducted in commercial fields using strip-tillage and conventional-tillage practices in Worth Co., GA. Main treatments consisted of cultivars Georgia Green and Florida MDR-98 in both years with the addition of C-99R in 2001. Sub-plot treatments were two fungicide treatments: (i) azoxystrobin (AZO) 0.33 kg/ha (sprays 3 and 5) and chlorothalonil (CHL) 1.26 kg/ha (all other sprays), applied at 14-day intervals; and (ii) AZO 0.33 kg/ha (sprays 2 and 4) and CHL 1.26 kg/ha (all other sprays), applied at 21- to 28-day intervals. Leaf spot ratings were 2.3 and 4.4 for Georgia Green and 1.9 and 3.3 for Florida MDR-98 (LSD = 0.4) for treatments 1 and 2, respectively, in conventional-tillage plots, and 2.1 and 2.9 for Georgia Green and 2.3 and 1.7 for Florida MDR (LSD = 0.2) in strip-tillage plots, respectively, in 2001. Lower levels of leaf spot severity in large strip-tilled plots of resistant cultivars were similar to results observed in small plot experiments. Leaf spot control in reduced fungicide regimes in strip-till was comparable to leaf spot control in the standard 14-day fungicide regimes. Thus, strip-tillage may reduce fungicide requirements for leaf spot control on Georgia Green, and should allow for even better leaf spot control when combined with resistant cultivars such as Florida MDR-98 or C-99R. Utilization of precision agriculture technologies aided in visualizing and explaining some of treatment differences for leaf spot, stem rot, tomato spotted wilt, and yield in 2000 and 2001. Accepted for publication 23 February 2007. Published 14 June 2007.