Japanese maple trees are often found in many yards and gardens. Home gardeners favour this tree because of its showy fall leaves. Japanese maple trees typically reach heights of 20 feet, but some smaller varieties are available. The Japanese maple tree is not low-maintenance because it is susceptible to insect infestations that affect its health and vigour.
The Japanese maple tree is also known by its scientific name of Acer palmatum and is a member of the Aceraceae family. This tree is often placed in the garden as an ornamental or specimen plant. During the fall, this tree produces a wild riot of showy red, orange and purple blooms. The Japanese maple is susceptible to leaf scorch, tar spot and nutritional deficiencies. This ornamental is also susceptible to a variety of insect infestations, although none cause serious damage.
Scales are a common pest of the Japanese maple. The cottony maple scale is characterised by white tufts placed on host trees. Scale insects are usually more active on indoor plants, but are found on a few outdoor trees and plants such as the Japanese maple, wax begonia, canna and rose. Mealybugs are also common Japanese maple pests. These tiny pests are covered with a waxy coating that looks similar to ground meal, which is where they received their name. Mealybugs excrete honeydew, which places the host tree at risk of developing sooty mould, a black fungus on plant leaves. Aphids also excrete honeydew and are often found on the Japanese maple. Aphids are often brightly coloured, very small and feed on the leaves of host plants.
Examine your Japanese maple tree for signs of insect infestations. The presence of sooty mould is a sign of heavy infestations of aphids, mealybugs or scales. Use a magnifying glass to inspect leaves for signs of insect feeding. Stippling or white flecks in plant leaves is a sign of insect feeding, as well as premature leaf drop and leaf bronzing. Trees infested with insects often have an unhealthy appearance.
Aphids, mealybugs and scales are best controlled by spraying your tree twice each week with a forceful jet of water. This process knocks insects from the tree leaves, reducing their numbers. Japanese maple trees with heavy insect infestations may require horticultural oil applications, as well. These products work by coating the insect with oil, reducing its ability to breathe. Horticultural oils work on contact; therefore, the entire tree must be thoroughly coated for best results. If your Japanese maple tree develops sooty mould as a result of insect infestations, controlling the insects reduces the effects of sooty mould.