Chestnut Pests and Disease

What pests, diseases, and cultural practices should every chestnut grower know about? The short answer: chestnut blight and Phytophthora root rot for diseases, chestnut weevil and gall wasp for insects, and proper site selection plus soil fertility for cultural care. Below are the details that matter on the ground.

Diseases of Chestnut Trees

Chestnut blight and Phytophthora root rot are the two major diseases of chestnut trees.

In eastern North America, where chestnut blight occurs, it is best to plant blight-resistant Chinese chestnuts. It’s important to realize, though, that Chinese chestnut trees vary considerably in blight resistance. Some individuals are quite susceptible while others are essentially immune to the disease.

Phytophthora root rot is mainly a problem on wet soils. There is genetic variation in susceptibility to phytophthora, but the best control method is to plant trees on well-drained sites. There aren’t any good fungicide treatments for either of these diseases.

Insect Pests of Chestnut Trees

There are many insects and mites which feed on chestnut leaves. Usually, the infestation levels are low enough that they don’t cause any economic damage, and control is not necessary. However, insects such as caterpillars and Japanese beetles occasionally become serious enough that control is warranted.

The chestnut gall wasp, which was introduced in the 1970s, has now spread over much of the eastern USA. It’s a serious insect pest that affects shoot growth, but has its own bio-controls that eventually render it a minor pest.

Ambrosia beetles, which attack large stems (especially graft unions), have caused serious problems in the South and Pacific Northwest.

In eastern North America, the chestnut weevil is probably the most serious economic pest of chestnuts. The larvae feed on chestnut kernels resulting in “wormy nuts.” Chestnut weevils are fairly easy to control with prompt harvesting of the crop or with insecticides. In spite of these and other insect pests, many growers produce quality chestnuts without application of insecticides.

Cultural Practices and Care

On good sites, chestnut trees will survive and grow with little or no care. However, from an economic standpoint, cultural inputs are justified in terms of increased yields, increased nut size, earlier yields, and consistent yields.

Maintaining adequate soil fertility is probably the most important cultural input — fertilize them as if they were peach trees. Other important inputs are weed control around young trees, mowing the orchard twice or more per season, and mulching the trees. Irrigation is probably justified on most sites.

Chestnut trees require much less pruning and training than other fruit trees. Pruning is done mainly after bearing begins and consists of removing lower branches to allow harvesting.

Get Advice for Your Site

Just contact us if you have any questions about chestnut trees, planting decisions, or your order for chestnuts, chestnut trees, or chestnut seed. For related growing information, see our pages on selecting chestnut trees, planting and care, and preparing chestnuts.