Foliage burn is most likely to occur when materials are applied to wet foliage or when extremely high temperatures follow application. Severe injury to foliage may result from spraying plants with equipment contaminated by previous use with hormone type herbicides. Common symptoms are severe growth abnormalities of leaves and leaf roll. Some herbicides are taken up by plant roots and cause a marginal burn. This burn develops inward to the veins of the leaf as the material is concentrated.
Defoliation eventually occurs.
New leaves are then formed which may also burn and defoliate. This will continue until the plant either dies or the chemical is no longer present in a toxic level in the root zone. Equipment used to apply herbicides should be well marked and should not be used for disease or insect control purposes. Some trees and certain ornamentals are sensitive to herbicides that are blended with fertilizers.