There are numerous insects and diseases, both native and non-native, that stress and kill trees. Insects and diseases that are currently important problems in this region include gypsy moth, Forest tent caterpillar, elm spanworm, hemlock wooly adelgid, butternut canker, beech bark disease, and dogwood anthracnose. Deer browsing continues to have a severe impact on seedlings and young trees in many forest areas in Pennsylvania. Acid rain is contributing to problems with forest health in certain localized regions where trees are exposed to highly acidic fogs and cloud masses on a frequent basis. Also, elevated concentration of ozone during the summer months is causing visible injury to plant leaves.
Most trees have no damage.
Some trees have wounds or damages on them. This does not mean that the damage is necessarily fatal. Overall, the forest is in good condition. Percent of trees over 10 feet tall that die annually from all causes in the Mid-Atlantic Region. Percent of trees that become new saplings annually in the Mid-Atlantic Region.