Why Does My Catalpa Look Sickly?

Have the sections of the tree been defoliated?

Have the leaves and shoots of your catalpa blackened and do the leaves have moist sunken spots on them?

Do the leaves and stems have black to brown spots on them?

Are there purplish to bluish-brown streaks under the bark in the sapwood of wilted branches?

Are the leaves covered with white powdery patches?

The larvae of the catalpa sphinx moth feeds on the foliage and can defoliate the tree. Females lay large clusters of eggs on the underside of host leaves or smaller clusters on twigs and branches. Young caterpillars feed together in groups; older ones feed singly. If the infestation isn't severe handpick caterpillars. Apanteles congregatus is a parasitic wasp, which lays its eggs inside the caterpillar. In more serious infestations spray BTK spray.

These symptoms are caused by fungal disease - Anthracnose. This disease is causing problems to trees mostly in cool and wet springs. In severe cases, twigs can die back and defoliation can occur. All diseased leaves and branches should be gathered and disposed of. Cut branches several inches below the damaged area. Larger trees will produce new leaves, so no control is needed for them.

Spotted leaves usually indicate fungal leaf spot diseases. Some fungal spots are surrounded by flecks or black dots, their spore-bearing fruiting bodies. Often spots come together to form larger patches of dead tissue. Pick off and discard infected leaves. Remove dead leaves to reduce overwintering spore populations.

A soilborne fungus Verticillium causes a disease called Verticillium wilt. There is no way to save a tree once it has this problem. Don't plant catalpas in soil that has sustained other Verticillium-susceptible crops such as tomatoes, peppers, and eggplants. If you suspect Verticillium fungi may be in your soil, solarize it for 1-2 months over the summer before planting Verticillium-susceptible plants.

White, powdery coating on the leaves is caused by a fungal disease Powdery mildew. Powdery mildew usually appears in damp places. Encourage good air circulation around the affected plants by thining any surrounding plants. Water plants from bellow to keep foliage dry. Any affected leaves should be cut off and removed. Any commercial fungicidal spray will protect your plant from further infections.

Root rot can be caused by overwatering or by poorly drained soil. Early in this disease, decreasing watering may be enough to save your plant. As the disease progresses, you may have to dig the plant. Water only when the top two inches of soil feels dry to the touch.