Response of Vegetable Crops to Sublethal Application of 2,4-D

Abstract

Sublethal amounts of 2,4-D [(2,4-dichlorophenoxy) acetic acid] were applied to several vegetable crops in order to determine effect on yield and quality in a simulated drift experiment. Tomato ( Lycopersicon esculentum Mill.) and root crops were most sensitive to 2,4-D; as little as 2.1 g/ha of acid distorted tomato fruit shape and elongated radish ( Raphanus sativus L.) roots. All root crops were rendered unmarketable by 10.4 g/ha and gross yields were reduced by exposure to 104 g/ha. Yield of peppers ( Capsicum frutescens L. var. grossum ) was increased by exposure to 2.1 g/ha and severely depressed by 104 g/ha. Cucumber ( Cucumis sativus L.) fruit shape was distorted at 11 g/ha and yield was reduced slightly. Lettuce ( Lactuca sativa L.), onion ( Allium cepa L.), and cabbage ( Brassica oleracea L. var. capitata ) were least sensitive to 2,4-D. Exposure to 20.8 g/ha did not reduce yields of lettuce or cabbage. Onion yields were reduced by application of 104 g/ha. Bush bean ( Phaseolus vulgaris L.) yield was decreased by exposure to 22 g/ha, but potato ( Solarium tuberosum L.) yield increased at 16 g/ha. Herbicide residues in the crop foliage were proportional to the degree of exposure. Residue analysis combined with foliar symptoms may be useful in predicting crop damage following 2,4-D drift.