By Julie Christensen
Like maples and oak trees, sycamores (Platanus occidentalis) are found throughout most of the eastern U.S. These stately trees, also known as American planetree, Button-wood or Button-ball tree, are easily identified by their leaves, bark and seeds.
Sycamore trees have large, light-green leaves that resemble maple leaves in shape. They are alternate, simple and palmate with coarse teeth. The undersides of new leaves are coated with coarse, white hair. In the fall, sycamore leaves turn yellow or brown.
The bark of a sycamore is distinctive. Young branches have white or gray bark that may be mottled. Older bark is dark grey to red. The tree’s unique seed balls are tan to brown and 1 inch in diameter. They form individually on slender stems in the fall.
Sycamore trees grow quickly to heights of 100 feet or more. Mature trunks might be 7 feet or more in diameter. Mature trees have a rounded, spreading form. The trees thrive in moist soils and are often found in woodland areas or near streams. They are hardy between USDA Plant Hardiness Zones 4 and 9.
Growing Sycamore Trees
Unlike other fast-growing trees, including cottonwoods and willows, sycamores are strong trees that can tolerate snow and high winds. Unless infected by disease, sycamores are usually long-lived trees. They are easy to propagate from hard wood cuttings and provide ample shade if you have the room for such a large tree.
The sycamore is a massive tree, unsuitable for most home landscapes. Not only is its size a problem, but its aggressive roots damage sidewalks, patios and plumbing. Sycamores are messy trees, as well, dropping ample amounts of leaves, seeds and twigs. Sycamores are planted most frequently in parks and public grounds. They are able to tolerate urban conditions, such as packed or alkaline soil and salt.
To grow a sycamore tree, plant a sapling or hardwood cutting in the spring in moist, deep soil. Keep the soil evenly moist throughout the first growing season as its roots become established. Sycamore trees prefer moist soils, although they will adapt to drier soils as they mature.
Prune sycamores in late winter. Prune out any branches that grow vertically or that rub against one another. If a second leader forms, prune it out to encourage one strong, central branch.
Diseases and Pests
Anthracnose. The most common and serious disease afflicting sycamore trees is anthracnose. The disease is most prevalent after wet, cool springs. It appears as dark, sunken cankers along the trunk and branches. The continual pattern of bud growth and death causes a witch’s broom appearance in the branches. You may also notice black fungal growths on the branches. Leaves become brown and mottled and drop early. To control anthracnose, remove and destroy all leaves in the fall. Do not compost them. Prune out cankered branches in winter when the tree is dormant. Prune the branches 3 to 4 inches below the cankers and clean your tools in a solution of 1 part chlorine bleach to 10 parts water between cuts. Spray trees in the spring at bud break with copper salts, cupric hydroxide or mancozeb + thiophanate methyl. Make additional applications every 7 days until temperatures rise above 65 degrees.
Bacterial Leaf Scorch. Bacterial leaf scorch is a bacterial disease spread by leafhoppers and spittle bugs. It causes leaves to become brown and drop early. It is rarely serious. To minimize damage from bacterial leaf scorch, plant trees in ideal growing conditions to avoid stressing the tree. Sycamores thrive in full sun and rich, moist soil.
Canker Stain. Canker stain is spread through open wounds on the tree so take special care during pruning to disinfect ladders, ropes and tools when moving from tree to tree. Canker stain causes small, sparse leaves and cankers on the branches and trunk of the tree. The wood under the canker is stained blue or reddish-gray.
Aphids are the most common pest to infest sycamores. They appear in droves in spring and suck the sap from the trees. They rarely cause any real damage, although the honeydew they secrete is messy and encourages the growth of sooty mold.
The best defense against diseases and pests is to plant healthy, disease-resistant trees, such as Columbia, Bloodgood and Liberty, which are clones of London planetrees.
Resources for further reading:
Sycamore Diseases – Penn State University
American Sycamore – Clemson Cooperative Extension
When she’s not writing about gardening, food and canning, Julie Christensen enjoys spending time in her gardens, which include perennials, vegetables and fruit trees. She’s written hundreds of gardening articles for the Gardening Channel, Garden Guides and San Francisco Gate, as well as several e-books.
Should there be concern when a mature sycamore has started showing vertical seams spread throughout the trunk of the tree?