Witch Hazel Tree Leaves Are Turning Brown in June

Gall Aphids

• Witch hazel gall aphids (Hamamelistes spinosus) are insects that infest the witch hazel tree and cause leaves to turn brown as early as June, with the foliage prematurely falling from the specimen. In most instances, a new flush of leaf growth will then occur before the end of the growing season. The life cycle of the witch hazel gall aphid is unique in that it spends part of the season on the witch hazel and the other part on the river birch tree.

Gall Aphid Management

• The gall aphid lays its eggs on the witch hazel in June or July with the eggs overwintering on the tree and hatching the following spring. After a complex process that involves the insect traveling to the river birch tree and then back to the witch hazel, a new generation of aphids begin to feed on the leaves of the witch hazel, turning them brown as early as June. The damage to the tree is chiefly cosmetic and chemical control of the gall aphid is rarely warranted.

Leaf Spot Diseases

• All shade and ornamental trees, including the witch hazel, are susceptible to a large number of fungi that produce a multitude of leaf spot diseases that result in leaves turning brown. Some of the fungi are particular to one species of tree while others may attack dozens. Phyllosticta leaf spot appears on many trees, including the witch hazel, and produces brown spots on the leaves. As the tissue dies, these spots may drop out of the leaves, resulting in a collection of holes within each piece of foliage.

Other Leaf Spots

• Monochaetia leaf spot and Mycosphaerella leaf spot disease also produce a series of brown spots on the leaves of a witch hazel tree. Additional colors and fruiting bodies of the fungus may also appear on the leaves. Eventually, nearly all types of leaf spot disease will result in the death of the leaves and premature defoliation. As these fungal diseases typically overwinter on fallen litter, infected leaves and twigs should be removed and destroyed each fall.