Birches (Betula spp.) are medium to large deciduous trees. They are prone to numerous pests, diseases and environmental problems and are relatively short-lived, especially in hot, dry areas where they may only survive for 20 years. Birches grow best in full sun in moderately moist soil. They need regular irrigation when planted in dry, sandy soil.
Yellow or brown foliage is a symptom of leaf scorch of birches. It is caused by hot, dry winds, drought or a nutrient deficiency. Affected trees usually recover once normal conditions return. Tattered leaves on birch trees are caused by freeze damage that occurred to the leaf buds before they opened, and no treatment is necessary. Several conditions cause the bark to split on the trunk or branches of birch trees. Vigorous growth caused by wet conditions after a dry spell can result in splitting bark. Severe cold weather followed by a rapid thaw causes frost cracks, and areas of bark damaged by sun scald can also split.
The most widespread pest on birches is the bronze birch borer. The birch leaf miner and the birch skeletonizer are also commonly found on birches. Other pests on birch trees include aphids, caterpillars, leafhoppers, sawflies and worms. Pests can be controlled with an insecticide approved for birch trees. Apply the pesticide according to the manufacturer’s directions.
Birch trees are susceptible to several fungal and bacterial diseases that cause leaf blisters, leaf spots and leaf rust. Most diseases of the leaves are not harmful. Other fungi cause twig die-back and cankers, which are dead areas of bark. Powdery mildew is a white to gray fungus that grows on leaves and stems in warm, moist conditions. Sooty mold is a fuzzy, gray fungus that grows on the honeydew secreted by the aphids. Some fungal diseases can be treated with fungicides approved for birch trees and applied following the manufacturer’s instructions. Some fungal diseases, especially cankers, have no treatment and cause the tree to decline and die.