Emerald ash borer (EAB) infestations are difficult to identify in the early stages of the infestation. Emerald ash borer infestation areas grow via human-assisted movement and through natural dispersion. For these reasons, when new emerald ash borer infestations are discovered, quarantines are enacted on a large scale (county) with the assumption that the infestation is spread beyond what is observed. However, while the quarantine necessarily covers a large area where emerald ash borer may be present, the distribution of emerald ash borer is likely not uniform throughout the quarantine and may be in areas outside these boundaries.
These guidelines ideally should be followed 100 percent of the time when working with ash trees throughout the state of Minnesota. However, once a community is heavily infested* with emerald ash borer, conducting ash tree removals during the emerald ash borer active period may be necessary to avoid risk to public safety and property. Following these guidelines will provide the lowest degree of risk for movement of emerald ash borer.
EAB Active Period - May 1 through September 30
- Avoid removal of ash branches, trees, stumps**
- If removal is necessary due to a hazardous condition then,
- Chip at least outer 1” of bark/wood on-site and transport to the nearest facility that can quickly process the material*** Or...
- Transport at least outer 1” of bark/wood in a vehicle where it is 100% enclosed to the nearest facility that can quickly process the material. Material should remain enclosed until it can be at a minimum chipped.
EAB Dormant Period - October 1 through April 30
- Conduct pruning, removal of ash as desired.
- Transport at least outer 1” of bark/wood to a facility where it will be processed prior to May 1.
- Point at which EAB infested ash are so numerous that year round removal of hazardous trees is necessary to mitigate risk to public.
**Active vs. Dormant Period
Branch / Tree / Stump removal should be avoided during the EAB Active Period for two reasons:
- By postponing pruning until the fall, you can help reduce the risk of EAB spreading. If the tree is left intact during the EAB Active Period, it can provide habitat for EAB adults to lay eggs. But since the adults won’t emerge until the following year, if this tree or branch is cut and properly disposed of during the EAB Dormant Period, any EAB that may exist in the ash material will be destroyed when the wood is destroyed.
- Material moved during the EAB Active Period may release adults at any time during transportation into a previously un-infested area.
***Disposal of outer 1” of bark/wood vs. whole tree
- Only the outer 1” of bark/wood harbors EAB. If this material is removed, the remaining wood may be utilized as desired and does not need to be destroyed.
- Options for effectively treating the material include grinding to a small diameter (less than one inch in two dimensions), burning or burying.