Emerald Ash Borer
Infestations in Chapel Hill and Durham!
“The non-native, invasive emerald ash borer (EAB) infests ash trees and is nearly 100% fatal.”
-National Parks Service
Last summer, 2019, we have found emerald ash borer (EAB) infestations in Chapel Hill, Durham, and Chatham County. EAB will do here what it has done elsewhere since its discovery in Michigan in 2002. It will kill over 99% of the ash trees greater than 1-inch in diameter. Whether the ash trees in your neighborhood are plentiful or few and far between, it doesn’t seem to matter. EAB is projected to kill them all. An updated national map can be found here. The pins in the adjacent map shows where we have seen EAB exit holes in infested ash trees during the course of our local tree assessments since the summer. Treatment options, considerations, and additional information found below.
map updated 2/17/2020
Soil Drench: For high-value individual trees on your property the NC Forest Service recommends treating them with preventative insecticides now. Imidacloprid soil drench is a cost-effective do-it-yourself treatment that can be done on an annual basis with no special tools. An Ohio study has shown that imidacloprid applied at the highest allowed application rate was effective on trees up to 22” dbh (“diameter at breast height”). While not currently locally available under the most effective formulations/labelings, this insecticide is widely available online (currently as Quali-Pro Imidacloprid 2F, as Criterion 2F, and as Lada 2F). One gallon of any of these formulations is sufficient to treat three 15” dbh trees every year for seven years. Trees are ideally treated in the spring, but summer and fall applications can also be effective. Product label instructions must be read, understood, and followed.
The Treeist offers soil drench treatments typically at $50 ($40-60) per tree, for trees under 22" dbh.
Trunk Spray: As a (faster acting but more costly) alternative to soil drench treatments, the root flare and lower trunks of trees can be sprayed yearly, in the tree’s growing season, with dinotefuran. Only requiring a simple pesticide sprayer, this treatment can also be performed by a homeowner. Dinotefuran can be purchased here or here as Safari 20SG, with the recommended bark-penetrating surfactant (Pentra-bark) purchased here. A 12-ounce jar of Safari 20SG is sufficient to provide one year of protection for three 13” dbh trees. Product label instructions must be read, understood, and followed.
We can offer this treatment for $10 per inch dbh, only for smaller trees (<18”dbh) where the bark is thin enough for it to be effective. While this treatment is generally not preferable, it can be useful late-season in the first year of EAB emergence in a new area, as a fast acting treatment to protect smaller trees before switching to a longer lasting or more cost effective treatment in subsequent years.
Trunk Injection: For stronger and more lasting protection, and for trees larger than 22-inches dbh, The Treeist, as well as several other local tree care services, can also offer emamectin benzoate trunk injections. This requires special tree injection tools, but the delivery to the tree is more rapid, the effects longer lasting (studies show it to be effective for two to three years), and the small amounts of insecticide are more precisely delivered to the target tree. Costs for this treatment vary with the diameter of the tree.
Beyond the product label directions, this recent fact sheet is the best we've seen for further discussion and directions for the insecticide options. As a companion, this fact sheet gives information on potential side effects and hazards of the relevant EAB insecticides.
For help identifying ash trees, go here.