Bark Beetles - Ask Extension
We have an oak tree that has been killed by bark beetles. We also have a white oak that is a seedling from the Maryland State Tree that is about 30 y...
Knowledgebase
Bark Beetles #860458
Asked March 04, 2024, 11:22 AM EST
We have an oak tree that has been killed by bark beetles. We also have a white oak that is a seedling from the Maryland State Tree that is about 30 years old. It appears that the bark beetles are now attacking that oak. Could you please advice us what to do to save this tree?
Howard County Maryland
Expert Response
Was an arborist able to confirm the presence of bark beetles (or their look-alike ambrosia beetles)? Many types of insects can bore into tree wood, either live wood just under the bark or the wood that's already (naturally) dead in its center. Bark beetles and ambrosia beetles appear to cause similar damage but feed in different ways, as illustrated in this helpful Ohio State article: Bark Beetles and Ambrosia Beetles.
One trait they do share (with rare exception) is the preference to target trees under stress as opposed to healthy trees. Tree stress doesn't always manifest in an obvious way until sometimes weeks, months, or even many years after the injury or adverse environmental conditions arose. This can include an over-saturated root zone (the excess rains of 2018 caused many mature White Oaks to decline years later), drought (this past summer was quite dry for many MD areas), root damage and compacted soil in the root zone, and pruning cuts that did not seal-over properly. Since wood-boring insects often seek-out stressed trees (they can essentially smell the chemicals released due to stress), there is no direct cure for infestation since the source of the tree's stress must be addressed and alleviated (if possible) instead. Beetle larvae tunneling in the wood are beyond the reach of insecticides. Those chemicals which may help to prevent a re-infestation by another beetle generation (which are sprayed on the bark surface) tend to be those that also pose a hazard to any other non-pest insect that encounters the spray residues.
If you haven't already, we suggest having a certified arborist assess the tree in person, where they can look at the canopy (which may be more informative when done once the leaves have emerged, so they can see how full it is), the bark on the trunk and major limbs, and the root zone (including looking for girdling roots), plus the condition of the soil in the root area. Arborists cannot treat or cure most maladies since pesticides cannot reverse any existing damage, but they can help diagnose a cause of decline and look for ways to reduce tree stress. For example, they have equipment which can reveal a girdling root that may be hidden by too much soil or mulch around the tree's base, covering-up its root flare. While potentially expensive to use, it can potentially save a tree's life.
Miri
One trait they do share (with rare exception) is the preference to target trees under stress as opposed to healthy trees. Tree stress doesn't always manifest in an obvious way until sometimes weeks, months, or even many years after the injury or adverse environmental conditions arose. This can include an over-saturated root zone (the excess rains of 2018 caused many mature White Oaks to decline years later), drought (this past summer was quite dry for many MD areas), root damage and compacted soil in the root zone, and pruning cuts that did not seal-over properly. Since wood-boring insects often seek-out stressed trees (they can essentially smell the chemicals released due to stress), there is no direct cure for infestation since the source of the tree's stress must be addressed and alleviated (if possible) instead. Beetle larvae tunneling in the wood are beyond the reach of insecticides. Those chemicals which may help to prevent a re-infestation by another beetle generation (which are sprayed on the bark surface) tend to be those that also pose a hazard to any other non-pest insect that encounters the spray residues.
If you haven't already, we suggest having a certified arborist assess the tree in person, where they can look at the canopy (which may be more informative when done once the leaves have emerged, so they can see how full it is), the bark on the trunk and major limbs, and the root zone (including looking for girdling roots), plus the condition of the soil in the root area. Arborists cannot treat or cure most maladies since pesticides cannot reverse any existing damage, but they can help diagnose a cause of decline and look for ways to reduce tree stress. For example, they have equipment which can reveal a girdling root that may be hidden by too much soil or mulch around the tree's base, covering-up its root flare. While potentially expensive to use, it can potentially save a tree's life.
Miri
