Maximizing Economic Returns and Minimizing Stem Rot Incidence with Optimum Plant Stands of Peanut in Nicaragua

Abstract

Abstract Peanut growers in Nicaragua use high seeding rates, often greatly in excess of the 19.7 seeds/m recommended for growers in Georgia. Significant yield loss to peanut stem rot (caused by Sclerotium rolfsii) often occurs because of rapid disease spread in high density plant stands. It was hypothesized that lower seeding rates would be beneficial, and field experiments were conducted from 2005 to 2006 in Nicaragua to determine the optimum plant stands for stem rot management, peanut yield, and maximum economic returns. The cultivar Georgia Green was planted in twin rows at seven locations with final stands of 4 to 30 plants/m. Paired plots were either treated or not treated with flutolanil to control stem rot. Stem rot incidence consistently increased with higher peanut plant populations in fields with significant levels (>5%) of stem rot. In fields with more than 5% stem rot incidence, peanut yield and gross income adjusted for seed cost were maximized at within row populations of 12 to 13 and 11 plants/m, respectively, when treated with flutolanil to reduce stem rot. When flutolanil was not applied, yield and gross income adjusted for seed cost were maximized at 10 to 11 and 8 to 10 plants/m, respectively. In locations with low stem rot incidence (<5%), maximum yield and gross income adjusted for seed cost were attained at within row populations of 13 and 12 plants/m, respectively. Nicaraguan growers may maximize their economic return by utilizing seeding rates to obtain final stand counts of 8 to 11 plants/m in fields with severe stem rot and 12 plants/m with low disease pressure.