We have discovered red headed ash borer on our 25 year old red maple tree - Ask Extension
Hello, This spring our red maple was slow to leaf out after maple seeds developed and this week it appears that leaves are dying. We had noticed the ...
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We have discovered red headed ash borer on our 25 year old red maple tree #870085
Asked May 25, 2024, 5:54 PM EDT
Hello, This spring our red maple was slow to leaf out after maple seeds developed and this week it appears that leaves are dying. We had noticed the last year or so that the bark at the base of the tree had started to peel away. We did not notice any bugs up until now. However today we have seen many red headed ash borers scurrying around the tree trunk and now see small holes. The only other strange thing we noticed was the last year of covid and this past fall, half the tree turned red in mid August much earlier than the other half of the tree. Any chance of treating the tree…..or is it too late? Thanks!
Montgomery County Maryland
Expert Response
The wood-boring larvae of Red-headed Ash Borers feed on dead and dying trees, so are only a secondary pest that arrives after some other factor first caused significant stress or damage to the tree. The borer galleries (tunnel systems) visible from the area of missing bark are not due to this beetle species, but they may be from Bark Beetles. (You can learn about how bark beetles damage trees, and how that damage compares to similar-looking borers called Ambrosia Beetles, in the linked page.)
Drought stress as well as over-saturated roots are common precursors to wood-boring beetle infestation, since they can detect trees under stress and choose them as preferred hosts. (Fairly few borers target seemingly-healthy trees.) Last year's season-long drought, for example, which affected most of Maryland, might have played a role, though it's hard to tell, since a beetle infestation might have begun years prior. Red Maple tends to be quite tolerant of wetter soils, so in this case over-watering is less likely, though we can't rule-out any impacts from the excessive rainfall we experienced back in 2018 and 2019, especially if the soil is compacted or drains poorly.
The early fall color you noticed was likely tied to the tree's decline from either bark beetle borers or other overlapping factors. Missing bark indicates dead cambium (sapwood) in that area of the trunk, which is not something the tree can heal since insects have already begun to degrade the wood underneath. Given the poor canopy condition in the photos and the existing trunk damage, the tree will not recover and will need to be removed if its eventual fall risks damaging property or harming people. (Otherwise, dead trees can still be valuable to wildlife like woodpeckers, owls, bluebirds, etc.)
Miri
Drought stress as well as over-saturated roots are common precursors to wood-boring beetle infestation, since they can detect trees under stress and choose them as preferred hosts. (Fairly few borers target seemingly-healthy trees.) Last year's season-long drought, for example, which affected most of Maryland, might have played a role, though it's hard to tell, since a beetle infestation might have begun years prior. Red Maple tends to be quite tolerant of wetter soils, so in this case over-watering is less likely, though we can't rule-out any impacts from the excessive rainfall we experienced back in 2018 and 2019, especially if the soil is compacted or drains poorly.
The early fall color you noticed was likely tied to the tree's decline from either bark beetle borers or other overlapping factors. Missing bark indicates dead cambium (sapwood) in that area of the trunk, which is not something the tree can heal since insects have already begun to degrade the wood underneath. Given the poor canopy condition in the photos and the existing trunk damage, the tree will not recover and will need to be removed if its eventual fall risks damaging property or harming people. (Otherwise, dead trees can still be valuable to wildlife like woodpeckers, owls, bluebirds, etc.)
Miri
Thank you for your reply and that is really depressing- I think it drains well on the hill on our front lawn, but not sure about the drought. Just very sad to lose it, was fantastic colour in the fall, and we are Canadian, so why we planted it when we moved in…
The arborists are coming next week to assess and provide a cost for removal.
Thanks again for prompt response.
Diana
You're welcome.
