The emerald ash borer (EAB) is not native to North America. It is believed to have arrived in the United States on solid wood packing material from its native Asia. The Emerald Ash Borer was first discovered in southeastern Michigan in 2002. Since its discovery, it has spread to parts of Ohio, Indiana and Canada. EAB is responsible for killing 12-15 million ash trees in this short period of time.
The adult beetles are metallic green, about ½ inches long and difficult to spot in trees. The adults lay eggs in the crevasse of the ash bark near the end of May or early June. The larval stage of this insect’s life cycle causes all the damage as it bores throughout the cambial layer of the tree disrupting the natural flow of water and nutrients from roots to shoots. In the spring, the larva turns into adults leaving the tree with a distinctive D-shaped exit hole.
The natural spread of EAB is about ½ miles or less annually. However, humans have greatly accelerated this process by transporting infested wood and landscape plant material unknowingly. Quarantines are now in place to prevent the movement of firewood, logs or nursery trees.
Michigan State University Extension Agency has provided a Homeowners Guide to Emerald Ash Borer Treatments. They have recommended two types of treatments: an insecticidal soil drench, and/or insecticide tree implants. The product they mentioned as a systemic soil drench is Bayer Advanced Garden ™. The label instructions recommend using 1 ounce of insecticide per inch of trunk circumference to be applied in May. This product is available in most local garden stores. They mention two tree implants, Bonide® Systemic Insecticide Bullets and ACECAP® 97 Systemic Insecticide Tree Implants. These cartridges are implanted into the tree trunk at 4-inch intervals. Follow label directions for drilling holes and inserting implants or bullets. Both products should be applied in late May. Michigan State University does not endorse the products mentioned over others.
It is important to note that these treatments must be applied every season. Homeowners also have the option of contacting tree care professionals to treat their trees. Professional Arborists have access to some systemic products that are not available to homeowners. Professionals also have spray equipment capable of treating the trunk and branches with a bore spray when the adult beetles are known to be laying eggs.
Hopefully, with the concerted efforts of the Universities, Government Agencies, and all concerned citizens, we will be able to save our ash trees for generations to come.