Nutritional chlorosis, however, displays a shaded or gradual fading of green from the yellow interveinal space to the green midrib without secondary veins. Foliar spotting may be a result of herbicide spray drift. Also, burn may occur where cupped foliage maintains direct contact between herbicide spray droplets or granules on plant foliage. It is essential that any herbicide residue be washed off the foliage of nontarget plants promptly after application. Overall necrosis, or death of tissue, is caused by a number of products and can occur in advanced stages of herbicide poisoning due to gross misapplication of chemicals.
Epinastic growth is foliage or stems which are abnormally twisted, cupped or otherwise distorted.
These symptoms often indicate some type of phenoxy herbicide damage. Chemicals of this type are root and shoot absorbed, which can cause injury in several different ways. Spray drift, root uptake and volatilization may all occur in this category. Symptoms are like those seen on dandelions or other weeds soon after application of a broadleaf weed killer to the lawn. Commonly grown woody plants in Oklahoma, such as redbud and grape, are two of many species very sensitive to minute amounts of phenoxy herbicides.