Sycamore Tree Fungus

The Platanus occidentalis, or American sycamore, is susceptible to a wide number of pests and diseases, including a variety of fungal infections. The consequences range from cosmetic damage to tree death.

Types

• The Apiognomonia errabunda and veneta fungi cause anthracnose, a serious tree disease, in sycamores. Several different types of phytophthora fungi cause phytophthora root rot, while the Botryosphaeria fungus causes Botryosphaeria canker. Other fungi that affect sycamore include powdery mildew and cercospora leaf spot.

Effects

• Trees with anthracnose develop sunken, damaged areas of bark called cankers, as well as leaf curl, defoliation and twig dieback. Phytophthora root rot infects trees from the roots, causing yellowing, limb dieback, stunted growth and plant death. Botryosphaeria canker damages the bark and weakens trees. The Erysiphe plantani fungus that causes powdery mildew creates small, powdery white patches on leaf surfaces. Cercospora leaf spot causes small, irregularly shaped spots on leaves, occasionally resulting in defoliation.

Prevention/Solution

• The Colorado State University Extension suggests planting the London or Oriental plane varieties instead of American Sycamore. Anthracnose infections are prevented by spraying trees beginning at bud break. Many phytophthora root rot outbreaks can be avoided by planting trees in well-drained locations. Irrigating and fertilizing trees prevents botryosphaeria infections. Powdery mildew is prevented by spraying plants with a fungicide before symptoms develop. Cercospora leaf spot is mainly cosmetic and does not require chemical control.