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

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 esculentumMill.) 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 sativusL.) 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 frutescensL. var.grossum) was increased by exposure to 2.1 g/ha and severely depressed by 104 g/ha. Cucumber (Cucumis sativusL.) fruit shape was distorted at 11 g/ha and yield was reduced slightly. Lettuce (Lactuca sativaL.), onion (Allium cepaL.), and cabbage (Brassica oleraceaL. 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 vulgarisL.) yield was decreased by exposure to 22 g/ha, but potato (Solarium tuberosumL.) 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.