Sycamore trees are shade-intolerant, slow-growing trees that grow as a single stem with an irregular orientation of its branches and are easily identified by their characteristic peeling bark and palmate leaves. A few diseases can affect a sycamore tree that, if left untreated, may lead to the tree's demise. Knowing what the signs of disease are, treatment modalities and ways to prevent infection may help these trees fight off disease.
Sycamore trees are deciduous flowering and fruiting trees that belong to the Platanaceae, or planetree, family. At mature height, these trees can reach up to 60 to 80 feet tall, according to the U.S. Department of Agriculture (USDA). The California sycamore (Platanus racemosa), Arizona sycamore (Platanus wrightii) and the American sycamore (Platanus occidentalis) are all native to North America.
Types of Diseases
Anthracnose on sycamore trees, also known as sycamore blight, is caused by Apiognomonia veneta, a fungus that forms acervuli--structures that produce spores. According to Colorado State University, sycamore anthracnose is also caused by Apiognomonia errabunda.
Powdery mildews on sycamore trees are commonly caused by two fungi--Phyllacytinia guttata throughout North America and Erysiphe plantani localized in Oregon and Washington, according to Oregon State University.
Sycamore trees are generally resistant to verticillium wilt, according to Utah State University, but the disease can affect compromised trees. Caused by the Verticillium albo-atrum fungus, verticillium wilt affects trees during the hot and dry season of the summer months.
Anthracnose is spread by its spores, and an anthracnose infection manifests as tiny water-soaked lesions on the leaves, according to Utah State University. These lesions eventually spread over the leaves and to the twigs and branches of the tree and eventually lead to their death.
The powdery mildew spreads from its conidia, or spores, that are carried by the wind. Once it lands on healthy leaves, it spreads over their surface, and the fungus takes its nutrients from the leaves. This causes the leaves to become deformed.
Verticillium wilt is very aggressive--it can affect a section of a tree or the whole tree in one season. It infects the trees through the roots and causes the leaves to wilt and die.
According to Utah State University, the use of chemical controls may be necessary during the wet spring months when the fungus is more likely to spread, but preventive measures may lessen the need for these chemical applications.
According to Oregon State University, fungicides can treat sycamore powdery mildew and are best applied when the fungus is most active.
Sanitation controls include removing dead leaves from the ground in the fall, pruning the sycamore tree of damaged branches and supplying the tree with adequate moisture and fertilization to increase the tree's resistance to the disease.
It is easier to promote and support healthy tree growth, with regular watering and fertilization to prevent a verticillium wilt infection, than to treat the disease, since this fungus lives naturally in the soil.
- Utah State University Extension: Ornamental Tree Disease--page 7 and 11
- Oregon State University Extension: Sycamore--Powdery Mildew
- Washington State University: Sycamore Anthracnose (Leaf and Twig Blight)
- SavATree: Sycamore Tree Disease Diagnosis, Treatment & More
- USDA Natural Resources Conservation Service: Arizona Sycamore