EAB in Minnesota's ash forests presents several unique management challenges. Black ash is our most abundant ash species and is well-adapted to growing in wet areas. Research is underway to find suitable tree species that might replace black ash, but the conversion to non-ash forests remains a major concern due to limited site accessibility and the expense of planting and growing non-ash trees on wet sites. Here are some general guidelines for landowners managing ash stands or mixed stands with a high percentage of ash:
- Avoid planting ash for ornamental, shade, or reforestation purposes
- If there is a market demand for ash, harvest it and encourage other tree species by planting or natural regeneration
- Call before you cut » Free assistance to help woodland landowners make informed decisions about timber harvest.
- Reduce the percentage of ash trees before EAB infestation through carefully-planned harvesting or tree planting
- Check out the DNR Forest Stewardship Program to receive technical advice and long-range management planning to keep your woodlands productive and in healthy condition.
In addition to the guidelines above, private forest managers are encouraged to consult Ash Management Guidelines for advice on how to manage ash in their forests and woodlands.
Be proactive when managing your ash trees. Ash trees can be treated with an insecticide to prevent infestation by EAB. Treatments must be repeated for the entire life of the tree—according to instructions on the product label—to be effective against EAB. If you are not interested in treating your ash tree, consider having it removed now by a professional tree care company and replant with a tree that is right for your area using sound planting practices. Waiting to remove your tree once it has become heavily infested or dead will end up costing you more money because these trees are difficult to cut down. Consider contacting an ISA-certified arborist to discuss the best course of action for your tree.
Generally, infested trees with more than 50 percent canopy decline are poor candidates for treatment because EAB has already caused significant damage to the tree. Lightly infested ash or trees with less than 50 percent canopy decline can recover if treated with an insecticide.
Begin insecticide treatments when EAB has a moderate to high risk of damaging your ash tree. This occurs when EAB has reached your community or neighborhood. If you highly value an ash tree, you could begin treatment when EAB is in your county, though you may be paying for unnecessary treatments because the risk of EAB damaging your tree is low. EAB can be tracked to the community and often neighborhood level using the Minnesota Department of Agriculture's interactive EAB status map.
The most effective insecticides are injected directly into the trunk. Injection by a professional pesticide applicator is the best option for trees greater than 48 inches in circumference or 15 inches in diameter. Sprayed and poured insecticides are not as effective and can drift or leach to surrounding areas and negatively impact insects and aquatic invertebrates. To determine the best insecticide option for your ash tree, consider contacting a professional who has a Minnesota Pesticide Applicator License, or visit the Homeowner Guide to Insecticide Selection, Use, and Environmental Protection.
What can I do to help?
The rapid spread of EAB is mostly due to human transport of infested ash firewood. EAB is a serious invasive tree pest, and consequently a quarantine has been placed in several counties to help prevent the spread of EAB to other areas in Minnesota. Firewood and other ash products are regulated by the Minnesota Department of Agriculture. It is unlawful to move:
- Ash logs and lumber out of the quarantine counties.
- Ash tree waste such as chips and mulch out of the quarantine counties.
- All hardwood (broadleaf deciduous trees) firewood out of the quarantine counties.
Detailed information about what is regulated is available at the EAB Quarantine and Regulatory Information website.