For Woodlot owners
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Like all native Wisconsin trees, ash trees play an extremely important role in forest ecosystem function. With emerald ash borer (EAB) now in Wisconsin, however, there are concerns about whether forest landowners should be harvesting ash before EAB arrives in the local area. The following management recommendations regarding managed forests and EAB are from Wisconsin DNR forest health specialists. Read about them in more detail in the Related Documents section below:
- Until EAB is found in the local area, continue regularly scheduled harvests.
- In stands where ash forms 20% or more of the basal area, reduce the ash component during regularly scheduled thinning or harvesting.
- When selecting ash trees to thin, first remove those that have low vigor and quality, maintain dominant and co-dominant ash trees with good form/health, and remember to follow the stocking guidelines for your forest type.
- During regeneration activities, promote species other than ash. In certain stands, this may require cutting or herbicide use on ash regeneration. The goal should not be to eliminate ash. Try to keep ash regeneration to 10% or less of all regeneration.
- If your land is located in or near EAB-quarantined counties, be sure to contact your forester to learn if you should adjust your management plan. For more on EAB quarantines, visit the State and Federal Quarantines section of this website.
- Know the risks of moving logs and firewood from and to your land. Visit the firewood regulations section of this website for more information.The Reality of EAB in Forests
Research on EAB in forests in Michigan and Ohio has grimly shown that all black, green, and white ash trees are susceptible to EAB attack regardless of ash density, total tree density, ash basal area, total stand basal area, ash diameter (above 1 in.), tree health, and species diversity. Ash survival decreased 30-50% over three years in monitored southeastern Michigan infested stands, and models developed from field observations predict that a healthy forest will lose 98% of its ash trees in 6 years.Rays of Hope for Ash Trees
Some progress has been made in managing EAB populations. A tiny native wasp was discovered killing EAB larvae at two sites in Michigan. Between 24% and 56% of EAB larvae at these two sites in 2008 were parasitized by this native wasp. We may yet discover more native insects that attack EAB and help reduce their populations. Scientists have released three parasitic insect species that are natural enemies of EAB in China at various locations in Michigan, Indiana, and Ohio. Two of these insect species have succeeded in establishing themselves at release sites.
Aside from biological controls, researchers have shown that a variety of chemical and microbial insecticides can protect trees from EAB attack. Many of these insecticides are available to homeowners to protect their ornamental ash trees, but some of them need to be applied by a certified and licensed pesticide applicator. They may have a role in protecting some valuable forest trees.
Regarding the resiliency of native ash, resistance to EAB has not been evident in ash to date. That is not to say that resistant native ash do not exist. In Michigan, ash regeneration on sites where EAB had killed overstory ash trees was common on mesic to dry-mesic sites, but the long-term outlook for this regeneration is poor since EAB will infest it once it reaches a large enough size.
Currently, in Michigan's Upper Peninsula, researchers are applying an array of management tactics to attempt to slow ash mortality due to EAB in two neighboring sites. If results from this project are positive, we may be able to apply them to Wisconsin's woodlands to buy researchers and our ash more time.
Finally, there is no way of predicting when EAB will arrive in a given stand. Researchers have observed that the spread of low-density EAB populations, without humans moving them, may be less than 0.6 miles/year, so a given ash stand in Wisconsin may not be affected by EAB for a long time. Artificial movement of EAB in firewood, nursery stock, logs, and other ash products may increase the rate of spread dramatically.For more information please contact your county DNR forester.
Management recommendations for woodlot owners
A list of Wisconsin Wood Residue Brokers, for property owners looking for a useful place to take woody "residue" after pruning or cutting.
Managing Emerald Ash Borer (EAB) Infested Wood: Regulations and Recommendations for Transport, Storage, Utilization, and Disposal (in PDF format).
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