White Hair Is Growing on My Tree Leaves

Powdery Mildew

• A white fungus resembling mass of white hair growing on tree leaves is a symptom of powdery mildew. This fungal disorder appears on the leaves of nearly all types of trees. The white hair is actually millions of fungal spores acting as the disease's reproductive mechanism, spreading it to adjacent leaves and other plants via wind, rain and birds.

Powdery Mildew Damage

• Powdery mildew thrives in humid environments and is less severe in arid climates. In addition to leaves, it may form on buds, flower, twigs and fruit. The leaves eventually curl, yellow and fall from the tree. Powdery mildew is primarily an aesthetic problem and rarely threatens the tree's overall health. Chemical control is usually not warranted unless the infection carries on for several growing seasons. At that point, the disease threatens the tree's vigor.

Fall Webworm

• The fall webworm (Hyphantria cunea) infests nearly 90 types of deciduous trees. It lays masses of eggs resembling white hair growing on tree leaves. These egg masses each contain several hundred, light-yellow eggs. Although adults emerge throughout the growing season, the adult female normally appears in June and lays her eggs on the undersurface of leaves. Larvae hatch within one week and immediately begin feeding on the foliage.

Webworm Effects

• The silken webs that the bug spins over the foliage at the end of branches are webworm infestation signs. These webs provide protected feeding areas for the larvae. The webs increase in number as the season progresses. The webs also may dangle from the tree through the winter, further increasing the illusion that a mass of white hair covers the tree. The tree may defoliate but rarely dies from the webworm's feeding.