Silver Maple Diseases With Branches Falling Off

Cytospora Canker

• Cytospora cankers are lesions that generally form on the silver maple tree's trunk or branches. The cankers are usually sunken, with raised, calloused borders. Small, black specks within the lesions may be visible. As the infection spreads, the canker girdles (encircles) the area. When the canker circles the trunk, all of the tree above the canker dies. When cankers encircle individual branches, they die and often break off and fall from the tree.

Rot

• Many fungal infections cause the maple tree's roots to rot, which interferes with the tree's normal circulation of moisture and nutrients from roots to crown. Twigs, branches and limbs may become deformed and desiccated. As the tree suffers branch dieback, the dead branches and twigs may drop to the ground. Phytophthora and Armillaria fungi commonly attack silver maple trees, as does Gloeosporium saccharinum. Most fungi thrive in moist, humid conditions. Improve drainage or cut back on watering, if necessary. Treat with a fungicide formulated for the specific pathogen infecting the tree and follow manufacturer's directions carefully.

Insect Vectors

• Insects such as borers and miners may transmit infections to the maple tree. These insects chew their way into the wood beneath the tree's bark, opening the door for infections and diseases to penetrate the tree. Aphids and other insects with suck the vital fluids from leaves, twigs and branches, causing damage and death. Prune away infested areas to eliminate insects and prevent the branches from falling unexpectedly and damaging property or injuring humans. Apply an insecticide formulated to kill the specific insect attacking the silver maple tree. If the insects transmit a disease, treat the tree with a fungicide or bactericide made to treat the disease. Follow manufacturer's instructions.

Verticillium Wilt

• One of the deadliest diseases of maple is caused by verticillium fungi. The infection causes the foliage along individual limbs to yellow and wilt, and the branches die. Acute infections cause the leaves to curl and dry out as they turn abnormally yellow or red. Dieback and branch death follow quickly. Keep the trees healthy to enhance their chances of surviving. Use balanced rather than high-nitrogen fertilizers and water the trees often to counteract the wilt, advises New Mexico State University Extenson. Use a systemic fungicide made to treat verticillium wilt if the tree is young. Mature trees may withstand the disease for years, but continue to weaken, dropping branches and limbs, and may eventually die. Healthy trees can outlive the infection if kept properly watered and fed, but may experience branch dieback every year.