Tools Used in the SLAM Project Areas
Girdled Ash Trees as a Survey Tool
By Steve Katovich, USDA Forest Service
The SLAM project primarily uses girdled ash trees to delineate and monitor EAB populations. Scientists have learned that EAB beetles are much more attracted to stressed ash trees than to healthy ash trees.
How do you “stress” an ash tree?
Trees can be easily stressed by removing a band of bark around the circumference of the tree trunk in the spring time before adult beetles have emerged. These “girdled” trees emit a number of chemical compounds into the air that adult beetles are attracted to. EAB adults prefer to feed on the leaves of stressed ash trees and more importantly, female beetles are much more likely to lay eggs on these trees than on healthy trees. So, girdled ash trees are the best survey tool available to delimit the boundaries of a known EAB population, especially a population that is relatively new to an area and still at very low levels.
Eggs hatch into larvae, then each individual larva quickly chews a tunnel (called a “gallery”) under the bark. In fall, the girdled trees are felled and the bark is carefully peeled off. The S-shaped galleries of EAB are very distinctive and generally confirm that the tree is infested. If no galleries are found then it is assumed that EAB has not yet spread into the area around that tree. If larvae are present, their developmental stage is determined and the numbers found in each tree are recorded. Scientists can use data from girdled trees to evaluate the density and potential growth of the EAB population in the area.
More information can be found on this weblink: http://www.na.fs.fed.us/fhp/eab/survey/eab_handout.pdf
and in these publications:
Systemic Insecticide Injections – One Option Used in the SLAM Pilot Project
Systemic insecticides are one option for controlling populations of emerald ash borer (EAB). A systemic insecticide is a product that is injected into the tree, typically at the base of the trunk. The tree transports the insecticide up the trunk and out to branches and leaves. The insecticide product controls adult EAB beetles when they feed on the leaves and may also control the larvae feeding under the bark.* Trunk injections with systemic insecticides reduce exposure for applicators. There is no drift, a problem that frequently occurs when insecticides are sprayed onto trees. Because the insecticide is contained within the tissues of the trees, insects that do not feed on the treated tree will not be affected. A systemic insecticide sold as TREE-¨Age™ is currently used in the SLAM Pilot Project. This product has been tested in research studies conducted in Michigan and Ohio. Results indicate it provides highly effective control of EAB for at least 2 years.
(see http://www.emeraldashborer.info/files/Multistate_EAB_Insecticide_Fact_Sheet.pdf) This product must be applied by professionals.Researchers test the effectiveness of systemic injections in ash trees versus other methods of control.
* SLAM treatments are not necessarily done for long-term protection of individual trees. Rather, trees are injected to create trees that are toxic to EAB so that we can try and keep the local EAB population at low levels. If homeowners or local landowners want to protect their tree long-term, they will need to retreat trees in the future.