Physiological leaf scorch is caused by excessive evaporation of moisture from the leaves. If the roots cannot absorb and transport water fast enough to replenish this loss, the leaves turn brown and wither. The bacterial leaf scorch pathogen, Xylella fastidiosa, can also cause scorching of leaves by plugging up the water-conducting tissues. If practical, apply a layer of mulch over the root system. Always plant trees adapted to your climate.
Adults survive the winter under peeling bark of the sycamore tree.
They become active in the spring at about the same time as leaves begin to develop. The adult female lays eggs on the leaf s undersurface, attaching them with a brown sticky material. The nymphs are wingless, darker than the adults are and covered with spines. Both adults and nymphs feed on the undersides of leaves. Around the feeding sites, the leaf tissue turns yellow.