Copper containing sprays will also defoliate peaches, plums and apricots. Frequent applications of sulfur may cause light foliage burn on rose and tender foliaged ornamentals when temperatures exceed 85 degrees F. Sulfur should not be used on cucurbit crops such as squash and cucumbers. Injury to plants may occur when materials are improperly applied or applied under adverse environmental conditions. 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.