Foliage Curls, Puckers, Turns Yellow. Leaves and blooms become stunted, and ants may be visible in the tree. They are attracted to a sticky honeydew secreted by aphids.
Aphids – Aphids are soft-bodied pear-shaped insects about the size of a pinhead. Either green, brown or pink, they cluster on tender new stems and under leaves to feed. For more information see the file on Controlling Aphids
Leaves Stippled Yellow. There will be fairly obvious fine webbing on leaf stems. The webs look like tiny spider webs.
Spider Mites – Mites are tiny insects about the size of a grain of black pepper. They may be red, black, or brown. They are barely visible, but they cause brownish stippling or pale yellow spots or blotches on the leaves. As mites suck chlorophyll out of the leaves, they also inject toxins into them, discoloring and distorting them. For more information see the file on Controlling Mites
Holes In The Trunk – Visible holes in the trunk near the base of the tree from which brown frass (sawdust) and gum exude show that borers are at work.
Peachtree Borers – Adult peachtree borers are wasp-like moths. They lay eggs around the base of the plum tree trunks in late summer and early fall. These hatch into white, 1 ¼ inch long worms with brownish heads. They burrow into the tree trunk as high as a foot above the ground or several inches below the ground. Young trees can be killed during the first season of infestation. Treat minor infestations by inserting a stiff wire into each hole and killing the worms. For more information see the file on Controlling Borers
Holes In Blossoms, Stunted Tree
Weevil – Weevils are reddish brown in color. They are about ¼ inch long with black snouts. Both larvae and adults may feed on leaves and fruit of the plum tree. The larvae make zigzag paths into roots, fruit, or stems. For more information see the file on Controlling Weevils
Gray, Velvety Mold on Leaves
Powdery Mildew – A coating of white or pearly gray, velvety mold on the ends of twigs, leaves and blossoms of the plum tree indicate powdery mildew. This fungus dwarfs the twigs and kills the terminal buds, spawing the growth of numerous side shoots. For more information see the file on Controlling Fungal Disease
Verticillium Wilt – Verticillium wilt causes leaves on plum trees to wilt and droop during midsummer or early fall. They later turn yellow, curl upward along the midrib, and drop. Leaf damage progress from the older part of the shoot to the younger growth. Prevent this problem by eliminating grasses and weeds around the plum tree. Do not plant vegetables such as tomatoes, cucumbers and peppers nearby. For more information see the file on Controlling Fungal Disease