Japanese maple trees are native to Japan, China and Korea, but they are grown widely in the United States for their beautiful foliage. According to the University of Illinois, Japanese maple trees are hardy between USDA Zones 5 to 8, and they need moist, well-drained soil in which to thrive. One of the downsides of growing Japanese maples is the pests and diseases they are susceptible to.
The U.S. Forest Service warns that aphids and scales are both pests that attack Japanese maples. Aphids will feed on the leaves and cause them to drop. Scales create cottony masses around the branches of the tree. Japanese beetles will also attack Japanese maple trees and eat the leaves, according to Bartlett Tree Research Laboratories. All of these pests can be controlled with pesticides.
The Bartlett Tree Research Laboratories and the U.S. Forest Service caution that Japanese maples can suffer from scorch caused by lack of water and from drying out during hot or windy conditions. Root problems, such as root rot and root collar canker, also occur in Japanese maples if they are grown in poorly drained soil. Verticillium wilt will occur if the Japanese maple is grown in soil with nematodes present in it. Both diseases show signs of wilting leaves and can cause the death of the tree.
Nutrient deficiencies can be a problem with Japanese maples as well, according to the U.S. Forest Service. Japanese maples need manganese, and without it they develop yellow leaves with dark green veins. To combat this, the tree needs manganese capsules implanted in its trunk.