Acer palmatum var. dissectum, or laceleaf Japanese maple, is a tree native to Japan, Korea, China, southeast Russia, and eastern Mongolia. Today it is found growing throughout the world's temperate climates. It is a small plant that is a popular choice for bonsai, container gardening, or a landscaping accent. The laceleaf Japanese maple may be susceptible to several insect and fungal problems.
Maples of this variety grow best in U.S. Department of Agriculture Hardiness Zones 6-9. This means that the lowest temperature that the plant will tolerate is -10° Fahrenheit (-23.3° Celsius). It prefers sun to light shade and has average water needs. The soil's pH level should be between 5.6-7.5, i.e., acidic to neutral.
This weeping, dome-shaped, woody plant grows to a height of zero to 10 feet (0-3 meters). Its leaves are 1-1/2 to 5 inches (4-12 centimeters) long, narrow, and serrated. They may be green, variegated, red to burgundy, or yellow-green to gold. From early to mid-spring, the laceleaf Japanese maple produces small red-to-purple flowers that hang in clusters. The flowers are followed by winged fruit that contains a 0.23-0.31 inch (6-8 millimeters) seed.
For hundreds of years, the laceleaf Japanese maple has been a popular choice for bonsai because of its beautiful shape. It may also be used in container gardens if its light and soil requirements are met. When used for landscaping, the tree does best when planted about 10 feet (3 meters) away from other trees. Planting in a somewhat shaded area will bring out the red tones in the leaves. These trees are one of the most popular landscaping trees in the U.S. and make a beautiful focal point or accent plant in almost any type of garden.
Aphids are green, brown, or pink pin-sized bugs that feed on the tree's sap. This may cause the leaves to turn brown or yellow or to curl. A laceleaf Japanese maple with an aphid infestation may be treated with an insecticidal soap.
The larvae of beetles, moths and sawflies are called borers because the adult insects bore holes into the tree and deposit the larvae. Borers cause leaves to drop and the tree trunk to scar. They may be prevented by wrapping the trunks in plastic, aluminum foil, or paper tree wraps, particularly after transplanting or when planting a young tree.
Anthracnose is a fungus that causes the leaves to develop sunken spots with pinkish pustules. All diseased leaves should be gathered and destroyed when they drop off the tree. The mulch underneath the tree should be replaced and infected branches pruned.
Canker fungus causes oozing sap lesions on the stems and trunk of infected laceleaf Japanese maples. The leaves wilt and branches die off. Severely infected trees cannot be saved and must be removed.
Mushrooms growing at the base of the laceleaf Japanese maple, thin, wilting foliage, and dieback of the top of the tree may all indicate shoestring root rot. Since fungus cannot live in dry conditions, the tree roots may be uncovered and exposed to air. Soil may be aerated and new organic material added. Very sick trees and the soil around them must be removed to prevent spreading to other plants.