Insects

Aphids

Borers

Scale 

Caterpillars

Diseases

Several fungi cause leaf spots but are generally not serious to warrant chemical control. 

Powdery mildew causes a white coating on the leaves. The disease is most common late in the season. 

Bleeding canker, caused by the fungus Phytophthora cactorum, forms cankers from which a brownish liquid oozes. Crown symptoms include leaves of smaller size and lighter green color than normal. In severe cases the leaves wilt and the branches die. There is no chemical control. Avoid feeding with high nitrogen fertilizers as it seems to worsen the condition of infected trees. 

Beech bark disease occurs when the feeding site of woolly beech scale is invaded by the fungus nectria coccinea var faginata. The fungus kills the bark and in the process, 
the insects. There are no satisfactory controls for the fungus. Control the disease by controlling the scale with a dormant spray of lime sulfur. 

Cankers infect, girdle, and kill branches. There is no chemical control. Prune out the infected branches. 

During periods of high temperatures and low rainfall beech may scorch. Make sure trees are adequately watered.