Fertilize trees in the spring and water well during drought to maintain tree vigor. Since this disease is not a serious problem for the health of the trees, chemical controls are usually not necessary. Bark disease, Nectria coccinea var. Feeding punctures made by the insects kill the living bark and produce cracks through which the causal fungus enters the tree. The fungus causes a canker which may be sunken, with small orange lumps of fungal tissue on the surface.
Leaves are usually yellow and small, and the tree lacks vigor.
When cankers are large enough to encircle the twig, branch, or trunk, the foliage wilts, and the parts of the tree distal to the canker die. Infection usually does not occur when the insects are removed soon after infestation. Fertilize trees in the spring and water well during drought to maintain tree vigor. Control the scale to prevent further infection. Leaves of beech are very tender when exposed to hot sun after prolonged cloudy weather, particularly when young.