Pest and Disease


Chestnuts have relatively few pests. First you will need to identify the pests and in many cases you can apply cultural and chemical management practices.

  1. Identify what type of bug(s) it is, by either self identification or by contacting your county local extension office to help with identification.
  2. Go to your local garden center to make your purchase most offer an array of either traditional or organic products. * important to consider the benefits in using organic products vs using traditional products and the Negative impact many chemicals have on pollinators (bees, butterflies etc) and our waterways.

Helpful Resource link to many common pests. Click HERE 

Japanese Beetles can be a severe problem in certain areas. Click HERE for recommendations on control techniques. Click HERE for more control techniques

Chestnut Gall Wasp – introduced by accident on budwood brought in illegally from China, this small wasp lays its egg in the growing shoots of the tree, causing a red colored gall to form and contorts the growth of the shoots. It can dramatically affection nut production. However, there is a predator wasp of the native Oak Gall Wasp that also preys on Chestnut Gall Wasp, and the population rise in Chestnut Gall Wasp usually triggers a rise in the predator wasp, and eventually the Chestnut Gall Wasp population declines and gets back into ecological balance. For more information click HERE.

The best prevention is to never buy trees from nurseries that are in Gall Wasp territory (essentially all of the eastern U.S. except Florida). You cannot tell if budwood or trees are infected because the larvae are microscopic and not visible to the eye.

Chestnut Weevil – this pest is spread throughout much of the eastern U.S. It is a small insect that lays its egg in the forming nuts on the tree, resulting in a worm inside the nut. The nuts fall to the ground, the worms crawl out of the nut and burrow underground, emerging the next summer as adults to repeat the cycle. There are chemical, cultural and post-harvest treatments available to control chestnut weevils. Ideally, a combination of cultural and chemical management would control the pest and eliminate the need for post-harvest treatment, which can diminish quality and the marketable yield. For more information click HERE.

Ambrosia Beetles – Ambrosia beetles were introduced into the Southeastern United States from Asia. Although it is still primarily a southeastern pest, the beetle is spreading into other areas.

They are rarely seen because of their small size and the fact that they spend most of their lives inside trees.

Most ambrosia beetles attack weakened, injured or dying trees and shrubs. Some attach fresh-cut wood as well. A few species attack apparently healthy trees and shrubs.

The first signs of damage by this beetle are fading or wilting of the foliage on the terminals of infested twigs and branches. Close inspection will reveal the presence of a tiny entry hole on the underside of the affected branch.

The symptoms of an infestation and granulate ambrosia beetle damage are unmistakable. As the female beetle tunnels, strands of boring dust, which look like toothpicks, extend from the tree. Young trees infested with the beetles usually die, but older trees may survive.

These beetles carry a fungus in their mandibles with which they inoculate the trees they infest. The larvae feeds on the fungus colonies, and it’s the fungus that is usually fatal to the tree.

Ambrosia beetles sometimes attack healthy trees, but they are especially attracted to trees suffering from stress. The insects enter at sites with damaged bark. Most ambrosia beetle prevention begins with reducing stress associated with trees.

Prevent stress as much as possible by watering the tree deeply during dry spells and keeping it on a schedule of regular fertilization as recommended for the species. Remove and destroy severely infested trees to prevent the infestation from spreading.

The initial attack by this beetle occurs in the spring. The first major adult is in mid-to late-February when temperatures exceed 65F.

As the female bores into the wood, a thin, toothpick-like strand of sawdust is pushed from the tunnel. This may extend an inch or more from the surface of the bark. While the females prefer to attack stems under three inches in diameter they will attack stems up to eight inches in diameter. The entry hole is about 2 mm in diameter. The tunnel goes straight into the heartwood and then opens into a cave-like brood gallery with one or two side galleries.

A major emergence of females occurs in early spring. Host plants may be heavily attacked at this time. If the host is vigorous enough, the beetles may be drowned or forced out by heavy sap flow. If the host is weak or not producing large amounts of sap, the attack will be successful.

Sprays that contain pyrethroids are effective at preventing ambrosia beetles from entering a tree. Use the spray according to the label instructions when you know that there are ambrosia beetles in the area. You may have to spray as often as every two or three weeks

If these treatments fail, and the trees die, all the research says to cut down the dead tree and burn it. Chipping does not get rid of the beetles.

Homeowners with valuable trees on their property should consider consulting an arborist. These professionals can assess a tree to determine the extent of the infestation and help you decide whether to try to save the tree. They also have additional products at their disposal that may help prevent the spread of infestation. For more information click HERE

Alachua, FL

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