Irrigation Rate and Fungicide Effects on Peanut Kernel Damage, Yield, and Net Return

Abstract

Abstract Field studies from 2002 through 2004 examined effects of irrigation rate and fungicide on peanut kernel damage, yield and net return in Gaines County, TX. Irrigation rates, the main plots of a split-plot design, were applied with a center pivot system planted in concentric circles, and represented a base irrigation rate (B)(ca. 75% of evapotranspiration), B + 33%, and B − 33%. Azoxystrobin or metalaxyl were applied to the subplots at 60 and 90 days after planting and there was a no-fungicide control. Irrigation rate had no effect on percent damaged kernels from harvested pods. Plots with B + 33% irrigation rate had higher pod yields (P < 0.05) than B or B − 33% irrigation rates in 2002 and 2003, but had similar yields to the B rate in 2004, a relatively wet growing season. Irrigation rate did not result in an overall difference in net return in any year. Plots treated with azoxystrobin had higher peanut grades and lower percent damaged kernels in all 3 yr than no-fungicide and metalaxyl treated plots. Azoxystrobin treated plots had higher yield and net return than metalaxyl treated and no-fungicide treated plots in 2 of 3 yr. Rhizoctonia spp. was the primary fungal pathogen isolated from peanut pods. Use of azoxystrobin resulted in an average net return of $170/ha. Azoxystrobin effects on yield were additive to water status across the entire spectrum of irrigation rates during the combined three years. Peanut producers from this region who want to maximize yield by increasing irrigation rate should use azoxystrobin if there is any history of Rhizoctonia pod rot.