Methyl Iodide plus Chloropicrin Rates and Formulations for Nutsedge Management in Tomato

Abstract

Two independent field studies were conducted to determine the efficacy of methyl iodide (MI) formulations and rates on mixed nutsedge [purple nutsedge (Cyperus rotundus) and yellow nutsedge (Cyperus esculentus)] stands and their effects on tomato (Solanum lycopersicum) yields. In both studies, treatments were rates of two formulations of MI + chloropicrin (Pic) at the 98:2 (v/v) and 50:50 (v/v) proportions. In the MI + Pic 98:2 study, the fumigant rates were 0, 100, 125, 150, 175, and 200 lb/acre in Spring 2004 and 0, 125, 150, 175, and 200 lb/acre in Fall 2004. In the MI + Pic 50:50 study, the rates were 0, 200, 250, 300, 350, and 400 lb/acre during both seasons. Additionally, a grower standard was included in each study, which consisted of plots fumigated with methyl bromide (MBr) + Pic 67:33 (v/v) at a rate of 350 lb/acre. Higher rates of MI + Pic 98:2 and 50:50 significantly reduced mixed nutsedge densities and increased relative marketable fruit weight of tomato. Plots fumigated with MBr + Pic were weed-free at the sampling times during both studies. Data from both studies indicated that MI + Pic 98:2 and 50:50 rates of 125 and 200 lb/acre, respectively, consistently provided the highest marketable fruit weights and mixed nutsedge control, which were similar to those obtained in plots treated with MBr + Pic.