Ash trees are a common tree species in Texas, with five native species residing in the state: Berlandier, Green, Mountain, Prickly and White. These species make up nearly 2% of rural Texas forests and anywhere between 3%-6% of urban forests. This may not seem like a lot, but in Austin, Texas, where there is only 3% ash, there are over one million ash trees.

    Ash trees grant us a variety of benefits. They provide shade from Texas’ harsh summers, purify our air and water, protect the soil from heavy rainfall and help beautify our outdoor spaces. They also provide food for birds, like cardinals and finches, and their wood can be turned into a variety of products. From cabinets to baseball bats, and even the floors of your home, you have ash trees to thank for it. Unfortunately, these marvelous trees are under attack, and they are losing badly. 

    Why EAB are a problem

    Emerald ash borers (EAB) are an incredibly destructive, invasive pest that preys exclusively on ash trees. Native to parts of Russia, China, Japan and Korea, EAB first arrived in the U.S. after hitching a ride inside the walls of a wooden shipping container. In 2002, the first population of EAB was detected in Detroit, Michigan, where the insects quickly spread, moving south until 2016 when they were first detected in Texas in Harrison County.

    Adult beetles are one-third of an inch long, one-sixteenth of an inch wide and possess flat backs with rounded abdomens. Their most obvious giveaway, however, is their metallic green coloration. Their young are much less pretty, resembling a flattened tape worm and can measure over an inch long, with a creamy white coloration. These larvae, specifically how they survive long enough to become full grown EAB, are what makes this insect such a problem in the first place.

    Female EAB lay their eggs just underneath the bark of an ash tree. Those eggs then hatch into larvae, which proceed to dig tunnels into the tree as they feed on it. These tunnels disrupt the flow of water and nutrients throughout the tree, resulting in it slowly dying of malnutrition and dehydration. EAB’s aggressiveness enables them to kill an adult ash tree in as little as one to three years once they have become established.

    Currently, 24 Texas counties are infested with EAB. They are:
    • Bowie
    • Camp
    • Cass
    • Collin
    • Cooke
    • Dallas
    • Denton
    • Franklin
    • Grayson
    • Harrison
    • Hill
    • Hood
    • Hopkins
    • Johnson
    • Marion
    • McLennan
    • Morris
    • Palo Pinto
    • Parker
    • Red River
    • Rusk
    • Tarrant
    • Titus
    • Wise

    Slowing the spread of EAB

    So how do we stop them? Firstly, if you want to stop EAB your best option is to plan ahead, specifically when it comes to the types of trees you plant. Planting a wide variety of trees, rather than just one species, increases your trees’ resilience to outside influences, including EAB. Examples of native species you can mix in with your ash trees include Texas persimmon, cedar elm, flowering dogwood, Texas hickory and many more. Planting a diverse arrangement of trees in this way will make it harder for EAB to establish itself in your ash trees.

    Secondly, you can help slow the spread of EAB in Texas by locally sourcing your firewood, instead of purchasing it from one part of the state and transporting it elsewhere. EAB can survive in firewood for up to a year, if not longer, meaning that by moving firewood you increase the risk of exposing previously uninfected counties to EAB. Learn more about the Don’t Move Firewood campaign, including where you can buy local firewood.

    Being able to identify EAB is also a good way to help stop them, as identifying their attacks early can give you more time to act. Tell-tale signs of EAB activity include ash trees with dead branches near the top of a tree, leafy shoots sprouting from the trunk, bark splits exposing zig zag larval galleries, extensive woodpecker activity and/or D‐shaped exit holes. Once you have identified an infested tree there are several actions you can take, starting with reporting it at 1-866-322-4512, the EAB hotline.

    Once EAB is in an area, however, you still have options. The primary one being to use one of the several commercially available insecticides that are registered for treatment of EAB. Application methods for these insecticides include soil injections, drenches, trunk injections or trunk sprays. Systemic insecticides that list emamectin benzoate as an active ingredient are highly recommended. If caught early, these pesticides can be used not only to eliminate EAB from a currently infested tree, but also to prevent EAB from taking up residence in that tree in the future.

    If that does not work, then your best course of action is to simply remove the tree. Dead trees should be disposed of properly to slow the spread of EAB and ensure the dead tree does not damage or harm any person, pet or property. The best way to do this is to hire a certified arborist who has experience removing trees infested by EAB. You should also always be sure that whoever you contract is insured and bonded in case of an accident, information real professionals should be happy to share. If you end up having to remove the tree yourself, it is vital you destroy it after cutting it down, as solely cutting the tree down will not kill the EAB inside and they may still spread to other trees in the area. The best way to destroy and dispose of an ash tree you have cut down is either to burn it or put it through a woodchipper. EAB can survive for years inside a dead tree so it’s imperative you destroy the tree where it is, rather than transport it elsewhere. Transporting infested trees, even when dead, may spread EAB to currently uninfested counties and make the EAB problem in Texas even worse than it already is.

    At the end of the day, whether you are preventing the spread of EAB or eradicating them on your own property, always remember that Texas A&M Forest Service is here for you. Whether we are providing you with information on EAB, setting traps to capture EAB for study, helping local communities prepare for EAB or alerting you of EAB movements, we are here to help. Click here to learn more about how you can stop EAB. With your help, we can protect ash trees, and all the wonderful things they give us, all across Texas!