Most gardeners grow Newport plum trees for their beautiful purple-bronze foliage and spectacular blossoms. While the Newport plum may be one of the hardiest purple-leaved plum trees available, it still remains susceptible to a variety of insects. Some insects do little harm, although they make the tree look unattractive, while the work of other insects can eventually kill the tree. Identifying the insects attacking the Newport plum is a good first step in knowing how to get rid of the pests.
Leaf Curl Plum Aphid
Less than a quarter-inch long, the pale green to yellow, pear-shaped leaf curl plum aphid turns dark green to brown later in the year. Aphids spend the winter as eggs on the plum tree before moving to other parts of the tree in the spring. When aphids feed on the tree's leaves, the leaves start to severely curl up, making the tree look very unattractive and unhealthy. One way to decrease the number of aphids living in the tree includes giving the tree a low-nitrogen fertilizer instead of a high-nitrogen feeding. During a mild infestation, the aphids may also be removed by hand.
Peach Tree Borer
The most destructive insect for a Newport plum tree, the peach tree borer, eventually kills the tree if not handled promptly. The action starts when adult peach tree borer moths lay eggs on the trunks of the tree in August and September. The larvae hatch in 10 days and immediately tunnel beneath the bark wherever they can find an opening. The larvae spend the next 10 months under the bark. When they finally emerge from the tree, borers drop to the soil where they eventually transform into moths. Meanwhile, the damage they create causes large amounts of sap at the base of the tree trunk; eventually, the entire tree may die. One way to manage these insects is to prevent damage to the tree that makes it easy for the borers to get through the bark. Avoiding injury to the tree from lawn mowers and weed trimmers as well as pruning and thinning the tree during cold months helps keep borers at bay.
Eastern Tent Caterpillars
Evidence of tent caterpillars occurs when gardeners see the insect's silky web nests or tents containing hundreds or thousands of caterpillars on their tree. All it takes are a few colonies of these insects to completely strip the leaves off a tree. Since the harm usually occurs in the spring, the tree survives by putting out a new set of leaves, but it expends much energy doing so. An easy way to get rid of the problem requires clipping off the tent from the tree and disposing of it in soapy water. Chemical control also works on ridding the tree of the larvae.