Soft Red Winter Wheat (Triticum aestivum) Cultivar Response to Metribuzin

Abstract

Greenhouse and field experiments, at two locations in Georgia, evaluated the tolerance of several soft red winter wheat cultivars (Triticum aestivumL.) to postemergence applications of metribuzin [4-amino-6-(1,1-dimethylethyl)-3-(methylthio)-1,2,4-triazin-5(4H)-one]. In the greenhouse, none of the cultivars growing in pots tolerated a 0.6 kg ai/ha treatment of metribuzin applied at the two-to three-tiller, six- to nine-tiller, or early-stem elongation growth stages. In nutrient culture, ‘McNair 1003’ was more tolerant to a 0.15 μg/ml concentration of metribuzin than other cultivars. Significant injury and yield reductions of wheat cultivars treated in the field with 0.6 and 1.1 kg/ha of metribuzin occurred. Differences between the cultivars were not uniform over all experiments. Increased injury was accompanied by higher rainfall and low temperatures subsequent to application. None of the wheat cultivars evaluated in the field experiments was injured by the 0.3 kg/ha rate of metribuzin. Acceptable selective weed control was obtained with this rate, indicating that metribuzin could be used in these soft red winter wheat cultivars.