Plum trees are susceptible to few insects, but the insects that plum trees are susceptible to are deadly to the plant. Pest infections should be taken seriously, and treatment applied as soon as possible. A healthy plum tree will produce luscious fruit that can be eaten or sold. If pests are allowed to infect the tree, the fruit can be ruined, and the tree may die.
Japanese beetles are small, reddish brown beetles with black heads. The backs of the beetles occasionally have a greenish tint to them in the sunlight. The beetle was transported to the United States in 1916 and has since plagued many plants, including plum trees. The beetles eat the leaves of the plant in grub and adult form. The grubs start their livee in the ground surrounding the tree. Beetles will attack during July to September.
The leaf curl plum aphid is named because plum leaves are one of its favorite foods to eat. The aphids are usually found inside leaves that are curled. The aphid is usually green, yellow or brown and is less than 1/2 inch long. The presence of the aphids cause the leaves to curl, preventing the completion of photosynthesis. This will stunt the growth of fruit or the tree and in severe cases can kill the tree.
The plum curculio is a beetle that is about 1/2 inch long. The adults are brown and scaly and have long pinchers in their mouths that they use to bore into the fruit. The eggs, larvae and adult beetles harm the fruit of the plum tree. The eggs are laid on the fruit, and the adults and larvae eat the fruit.
Rust mites will also attack the plum tree. The mites are less than 1/4 inch long and can be yellow, red, pink, white or purple. Signs of a mite infection include leaves that turn silver and curl up. If these signs occur, look for small patches of the mites on the underside of curled leaves.
Preventing these bugs from gaining a foothold on your tree is simple. Many of the pests can be eliminated with a pesticide spray. Control Japanese beetles by shaking the branches of the tree so that they fall to the ground. Place the beetles in soapy water to kill them. Spray the tree with neem oil when you spy an infection of aphids. A Petal-fall pesticide applied in fall will prevent plum curculio. Control rust mites with a sulfur spray applied in early spring.