Vine maples (Acer circinatum), hardy in U.S. Department of Agriculture plant hardiness zones 4 through 8, are understory forest trees in the wild. In landscapes, they are often focal points and planted singly or as a clump. They have irregular trunks and branches, and they produce nearly round palmate leaves. They are well-known for their bright red and orange fall colors. They suffer from few diseases or infestations; however, they may occasionally contract a disease or acquire a pest when under stress.
Maple decline is a collection of symptoms contracted by maples living in urban environments. Because these maples are planted in disturbed or compacted soils and subject to air pollution, leaves and branches may react by producing smaller leaves or leaves that appear scorched. Decreased vigor could be caused by root girdling brought on by compacted soils, restricted roots or drought. Trees planted near the street may become burned by de-icing salt. This stress may cause the tree to decline, but the general weakness caused by this environment may also invite infestation by insects or diseases.
Vine maples aren't often infested by insects but may invite pests if under stress. One of the most damaging is the Asian longhorn beetle. Although more common in the northeastern United States, certain locations in the West are also vulnerable. Asian longhorn beetles bore into the woody portions of maples and other trees, feeding on the trees juices. Symptoms include holes in the bark, and piles of coarse sawdust appear around the tree's trunk and in branch axils. The insects are quite showy -- they bear black bodies with white spots and long, striped antennae.
Piercing and Sucking Insects
Both maple aphids and red crossed stinkbugs suck on the sap of maple trees, and they may attack stressed vine maples. Maple aphid symptoms include summer leaf drop and honeydew drops on leaves, sidewalks and patios. The adults are green to black bead-sized insects, and the eggs are white. The red crossed stinkbug sucks on the fluids in leaves, similar to the maple aphid; however, it leaves behind no honeydew. The adult is a green, wedge-shaped insect with a red cross on its back, and the nymphs are bright red. The nymphs do the most damage.
Nectria dieback is a fungal disease that feeds on dead tissue, but it may invade live stems and branches weakened by other factors. It causes canker on woody parts of the tree. The first symptoms of the fungus verticillium are midsummer wilting on one side of the tree and brownish streaks in the sapwood. It usually takes a couple of years, but it is often fatal to the tree. Anthracnose is a fungal disease that causes small areas of dead tissue on any part of the tree. These dead areas grow in size and may eventually kill the tree. Anthracnose can mimic leaf scorch when leaves are affected, but anthracnose occurs in cool, wet weather while leaf scorch happens in hot, dry weather.
- Natural Resources Canada: Asian Longhorned Beetle
- Natural Resources Canada: Redcrossed Stink Bug
- Natural Resources Canada: Nectria Dieback
- Oregon State University: Pacific Northwest Nursery IPM
- Pacific North West Plant Disease Management Handbook: Maple (Acer sp.) -- Verticillium Wilt
- Cornell University: Asian Long-Horned Beetle
- Iowa State University: Maple Aphids
- Photo Credit Comstock/Comstock/Getty Images