These trees usually have no insect pests. While Chinese Chestnuts are very resistant to the Chestnut blight disease, they are not totally immune to it. If you see cankers growing on the branches and then moving into the trunk, you want to get the advice of a certified arborist immediately.
Fails to Produce Nuts
Caused by Late or Early Frost
Trunk and/or Branches Girdled
Borers - Two-lined Chestnut borer (Agrilus bilineatus) larvae make interconnecting galleries under bark and may girdle the trunk and branches. They are about 1/2 inch long. Adult beetles are 3/8 inch, black with 2 narrow converging longitudinal pale stripes on the wing covers. Larvae work in the inner bark and outer sapwood, pupating in cells in the wood. Other borer pests include - Brown wood borer (Parandra brunnea), dogwood borer (Synanthedon scitula), and twig pruner (Elaphidionoides villosus).
Holes in Leaves
Caterpillars - Caterpillars come in lots of sizes and colors since they are the larvae of many different kinds of moth. When the hungry larvae of these moths, caterpillars, emerge to feed on tree foliage, they are capable of serious damage to the tree if present in sufficient numbers.
Wormy, Deformed Nuts
Weevils - Insects attacking American Chestnuts are insignificant because most of the trees have been destroyed by Chestnut blight. However, 3 species of weevils (Curculio cartrypes, C. sayi and Cyrtepistomus castaneus) may seriously damage nuts of Asiatic Chestnuts. Larvae residing in the nuts can be killed by immersing them in water at 1F for 30 to 45 minutes, depending on the size of the nuts. Gather nuts from the ground daily to prevent grubs entering the soil. If you have chickens, let them run beneath infested trees to snap up emerging adults. Chestnut weevils which lay eggs in the burrs and subsequent grubs eat nut eats.
Dead Blotches on Leaves
Leaf Spot - Leaf spot fungi cause dark red or purple spots on the leaves of trees that rot out, leaving holes in the foliage. Heavily infected leaves turn yellow or brown and fall prematurely. Cool, moist spring weather encourages this disease when new leaves are developing. Shake out all fallen and diseased leaves from the tree and destroy them. Remove all dead branches in the center of the tree to allow better aeration. Mulching helps prevent the disease from splashing up from the ground and infecting plants.
