Ash anthracnose is a disease that affects Denver ash trees causing black blotches on leaf margins, leaf distortion, and small brown spots on leaves. To help reduce stress on Ash trees when affected by anthracnose, it’s important to fertilize them to help reduce reoccurring stress. Anthracnose is not usually damaging enough to stress a tree in a single year. However, when they are defoliated for three or more years in a row, they will become stressed and are susceptible to pests that could eventually kill them.
One of these pests is the ash leaf curl aphid - also called the wooly aphid because of the thread they create to cover their bodies. To survive, they feed on plant juices on the underside of ash leaves. When an aphid does this, it causes leaves to curl and become deformed. Usually, aphid’s natural enemies are good at keeping the population down, however, because of their rapid reproductive rate and short life span, there can be damaging population explosions.
It’s helpful to keep your tree healthy so that an infestation doesn’t damage or stress your ash tree. In hot weather, make sure that you water your tree frequently. With larger infestations, make sure to call American Arbor Care, Denver’s professional tree service, and use a proper insecticide for the problem. Check out our other advice for managing pests and diseases in your lawn