Leaf scorch is a physiological problem related to watering. The leaves lose water at a faster rate than can be replaced by the plant. Leaf scorch can be caused by anything that can interfere with the uptake of water. Leaf scorch is not a disease and is often caused by a variety of issues.
What causes Leaf Scorch?
Environmental conditions that increase the water demands on trees include hot temperatures, low humidity, high light intensity, and high winds.
Strangely enough, leaf scorch can also be caused by excessive water in the soil. Saturated soils do not allow roots to get access to oxygen. As roots suffocate they start to die and the tree cannot take up water as the leaves are dying out. This situation is most common in heavy clay soils.