Rotate with crops that are not seriously affected by this organism. Practices which hasten decomposition of crop residue may help decrease the population of the fungus in the soil. Browning or yellowing of the leaf margins and brownish or discolored irregular areas on leaves are common symptoms of chemical burns. Severe injury may be evidenced by distortion of new leaves, or defoliation, but unless some serious mistake has been made, spray or dust injury is not an important consideration. Pesticides in emulsifiable formulations are more likely to cause foliage burn than wettable powders, particularly when combined with wettable powders.
Stone fruits are sensitive to copper.
Bordeaux mixture causes russeting of apples and may stunt cantaloupe and watermelon leaves. Copper compounds should be used with caution on any cucurbit crop. Injury is most likely to occur when materials are applied to wet leaves and under damp, slow-drying conditions. 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.