Emerald Ash Borer (EAB)
EAB in Ramsey
On December 11, 2019, EAB was confirmed in two trees in Ramsey. It appears that one tree had been infested for several years already simply based on the amount of woodpecker activity throughout the tree and along the trunk. The second tree appeared to be more recently infested as very few signs of EAB were visible other than a single larval gallery and exit hole.
The confirmation of EAB in Ramsey is not really surprising giving the proximity to other known infestations. Additionally, EAB had been found in Anoka County already, dating back to 2015. At that time, Anoka County was entered into a state and federal quarantine in an attempt to limit the further spread of EAB. The find in Ramsey does not have any impact on the existing quarantine.
EAB is an invasive insect from Asia that was first discovered in Detroit, Michigan in 2002 and was confirmed in St. Paul, Minnesota on May 14, 2009. Since that time, EAB has been confirmed in at least nineteen (19) Minnesota counties. The Minnesota Department of Agriculture keeps up to date information on new finds and quarantines.
EAB is responsible for the loss of millions of ash trees in other states already. Minnesota has the second largest population of ash trees in the country and so the economic and environmental impact of EAB could be devastating. EAB appears to attack all types of native ash trees (Green Ash, White Ash, and Black Ash) regardless of whether they are healthy or under stress. Adult insects are slender, bronze or golden green with dark metallic green wings, and about ¼ to ½ inch in length. However, it is the larval stage that causes all the damage. The larvae can be 1-1¼ inches long, are cream colored with a brown head. EAB larvae feed on the tissues just beneath the bark and can ultimately girdle a tree.
Signs of EAB
The larvae feed on the cambial area between the inner bark and wood, which disrupts the trees ability to transport sugars from the leaves to the roots as well as the water and nutrients from the roots to the canopy. Over several years time, an infested tree will die. Note that unlike some species, when ash trees die, they can become fairly brittle rather quickly, resulting in possible hazard tree conditions. One of the best tools for early detection of EAB is to look for evidence of woodpecker activity during leaf-off conditions. Other signs of an EAB infestation may include the following:
- Woodpecker Damage
- Dieback in the upper canopy (PDF)
- Epicormic branching on the trunk of the tree and woodpecker damage evident on the bark (PDF)
- S-shaped galleries created by the feeding of larvae just under the bark (PDF)
- Single larval gallery (PDF)
- D-shaped exit holes from where the adult insect emerges from the tree (PDF)