Emerald Ash Tree Borer Treatment: Tips On How To Prevent Ash Borer

Marks On Tree Bark From Ash Borer Insects
(Image credit: ziggy1)

The Emerald ash tree borer (EAB) is an invasive, non-native insect discovered in the U.S. during the last decade. Ash borer damage is significant in all species of North American ash trees that become infected. Susceptible trees include white, green, and black ash. Know where your ash trees are located and scout for the pest in June and July as the first step to prevent ash borer from causing serious or deadly damage.

Emerald Ash Borer Characteristics

The emerald ash borer is so named for its emerald, green color. The insect is about ½ inch (1 cm.) long and leaves D-shaped holes when exiting the ash trees interior. The pest lays eggs and leaves the larvae to hatch inside the valuable ash trees, where they create serpentine tunnels that interfere with the tree's ability to move water and nutrients throughout its tissues. Learning how to protect ash trees from ash borer can save your trees.

How To Protect Ash Trees From Ash Borer

Controlling the spread of emerald ash borer begins with keeping ash trees healthy and unstressed. The insect is usually spread through human activities, such as moving infested firewood. Prevent ash borer by inspecting firewood closely before purchasing and buy locally when possible. Do not transport firewood if you live in an area that has an ash borer population. Identifying ash trees is another step to lessen ash borer damage. Insecticidal treatments may slow damage to trees that are valued for shade or historic purposes. Ash tree borer treatment should be applied in May before the adult insects emerge. Ash tree borer treatment is not needed until the emerald ash borer is spotted within a 15 mile (24 km.) radius, unless symptoms are visible on your ash trees. Symptoms include canopy dieback, D-shaped exit holes, and bark splitting on your ash trees. If you see what appears to be ash tree borer damage, you may contact a certified arborist about how to protect ash trees from ash borer and what ash tree borer treatment works best in your situation. The tree professional may do systemic injections to kill larvae already inside the tree. Visible emerald ash borer characteristics and damage may be lessened with soil treatments and bark and foliage sprays. For the homeowner who spots ash borer damage and wishes to do their own ash tree borer treatment, a soil application of imidacloprid can be applied (such as Bayer Advanced). Most chemicals to control ash borer damage require a pesticide applicator license for purchase.

Becca Badgett

Becca Badgett was a regular contributor to Gardening Know How for ten years. Co-author of the book How to Grow an EMERGENCY Garden, Becca specializes in succulent and cactus gardening.