Growth regulator herbicides are often of most concern for drift damage to vegetable crops. This group includes dicamba, 2,4-D, MCPA, MCPP, triclopyr, picloram, clopyralid, and aminopyralid. Some of these herbicides can drift over one mile from where they were applied when volatilized.
Symptoms include leaves becoming cupped, crinkled, puckered, strap-shaped, stunted, and malformed. Leaf veins can appear parallel rather than netted, and stems become bent, twisted, and brittle.
Growth regulator herbicide injury symptoms will be concentrated on the upper part of the plant (growing points).
Growth regulator herbicide damage on tomato. Note leaf cupping, strapping, twisting, and unusual vein pattern.