Saving Your Ash Tree from the Emerald Ash Borer in PA and NJ
By John Stonaker, Nov 26 2019 12:14AM
The Emerald Ash Borer is a small metallic green beetle from Asia that, in the last 14 years, has killed millions of ash trees and threatens billions more in forests wherever this invasive insect has been found. You must take immediate action to protect your trees because the ash tree dies within 2-3 years of infestation. Pre-treating healthy trees is recommended, as well as immediate treatment of infected trees at the first sign of infestation. No time can be wasted, and treatment must be ongoing to keep this destructive beetle at bay.
The adult beetle does not harm people and does minimal damage to trees, except to lay its larvae under the bark of the ash tree. These larvae remain in the tree for 1-2 years, chewing through the wood right beneath the bark, called the xylem, which carries water and nutrients throughout the tree. As the xylem is destroyed, so is the tree’s ability to provide nutrients to its extremities, and it begins to die.
Signs of infestation
Look for the following signs of infestation:
• Tree canopy die-back: the tree dies from top-down because the xylem cannot carry water to extremities
• Leaves that look discolored or chewed, ragged on the edges because of adult feeding
• Exit holes on trees that look like a 1/8th-inch D-shape or half-circle caused by emerging adult ash borers
• Woodpecker activity as woodpeckers feed on larvae
• Paths called galleries on the inner bark from the larvae feeding on the inner bark and xylem – not visible exteriorly
Appropriate treatment depends on the level of infestation. If the tree has lost more than 50% of its canopy, treatment is not likely to save it. It should be cut down and chipped quickly to prevent spreading, preferably in the fall or winter when the larvae are dormant. All chips should remain local and wood can be burned locally as firewood.
However, if the damage is not yet that serious, you may choose to treat it. Treatment involves the application of chemicals – either by drilling holes and injecting chemicals into the xylem or by heavily treating the bark. These chemicals are then carried through the tree by the xylem, the very part of the tree the larvae feed on. Drenching the soil with the chemical is also a safe option if the tree is healthy enough to draw sufficient nutrients from the soil.
Young larvae are more susceptible than older larvae, so summer applications are more effective. However, if you discover the problem at a different time of the year, do not wait for further damage. Have the tree treated, but consider more frequent applications to kill the older larvae. Foliar spray can also be performed to treat adult or emerging beetles. Pruning of all damaged limbs should, of course, be a part of the treatment.
Pruning and the application of chemicals should only be performed by a licensed tree professional, for your own safety and the safety of your property.
If you have an ash tree and it still looks relatively healthy, don’t press your luck. Immediately contact a qualified tree service to begin treatment, because it is estimated that 99% of untreated ash trees will succumb to ash borer infestation. By preventing an infestation with regular treatment, you can save your tree and prevent the further spread of this invasive pest.