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Plant Diseases/Damage to Outer and Inner Bark Autumn Blaze Maple


 Autumn Blaze Maple Insect Cropped
Autumn Blaze Maple In  
Full Area of Damage
Full Area of Damage  

I planted two 3 inch caliper about 15 foot high Autumn Blaze Maples in the fall of 2010. They sometimes develop cracks in the bark in the spring which heal over within a growing season.

The one tree which is about 5.5 inch thickness measured 6 inches off of the ground, has an area about 2 inches wide by 3 inches high which had a bark crack on the left side and a hole in the top and bottom of the right side of this area. Pushing on the outer bark I could feel it was hollow behind it.

I did notice a dead mothlike bug with folded wings with its butt sticking out of the crack. The butt was kind of striped. I pulled out the bug laying it on the ground but it was gone when I returned later. Not sure if it just blended in well with the mulch or something ate it.

I stuck a stainless steel hooked prob into the holes and out popped an insect which is displayed in the attached photo. There was a second identical insect that came out of the other hole. There was soft wet powdery dead material coming out of the holes.

Since the area behind the bark was hollow and the bark seemed to be dead over this area, I carefully removed it starting from the crack on the left. I have attached a photo of the area after the bark was removed.

Besides the outer bark I removed, it appears the cambium and maybe phloem inner bark areas are gone in this area in the photo. Please also notice a crack in the inner wood. This crack travels up higher than the exposed part of the wound. This wound is about 36 inches from the ground level.

What options are there to address the wound in the tree to stop further damage?

Could I apply some type of caulk to seal the crack in the inner wood? Are there a compounds like tree wax, cement, etc that I can use to fill the 2 inch by 3 inch void in the missing outer bark, the cambium, phloem missing layers?

My goal is to stop fungal infections and stop other insects from making this part of the tree trunk a home.

I appreciate any ideas you have to offer to seal this area.

Thank You,


ANSWER: The picture of the insect is an earwig it is feeding on the fungi under the bark and not what is causing the problem. The damage looks like a borer. These beetles bore into the bark and live under the bark and into the wood. I would spray the tree with an insecticide called Merit or one called Onyx. You can also use a product called Bayer Advanced Tree and Shrub Insect Control. It is applied to the soil around the tree and the roots carry it to the parts of the tree and when an insect feeds it is killed. It will protect the tree all season long. Check with your local garden type store for these insecticides. j

Also borers attack trees under stress. So I would fertilize the tree with 10-10-10 fertilizer at the rate of 1 lb per inch of trunk diameter scattered around the tree and watered in good. Apply just before a rain event and you will not need to water. This will increase the overall health of the tree and help ward off insects like borers.

I would not apply and dressing or caulk to the wounds. You can gently remove the loose bark but the dressing will slow down the healing process. The tree over time will heal over the wound.

---------- FOLLOW-UP ----------


Thank you for your very detailed answer and identifying the culprit as a borer. I noticed a new pair of holes about 3 inches off of the ground on the same tree. There were earwigs in these holes too.

I will look for Merit to spray on the trunk and limbs of the tree. Should I spray the Merit into the crack in the inner wood that goes above the visible wound in the photo?

I do apply Bayer Tree and Shrub to this tree and all the trees I planted and have been doing so for at least three years now adding an ounce per inch of circumference of the tree 4 feet up. I also apply Job's Tree fertilizer spikes every spring. This year I think I added 4 or 5 spikes around the trip line in April. Should I still add 10-10-10?

Thank you for your input!



Yes spray any damaged area with the Merit This will kill the insects under the bark. Since you are using the fertilizer spikes  I would not fertilize with the 10-1010 now but would use it instead of the spikes next spring and then after. The spikes May then dot burn any root that might come in contact with the concentrated fertilizer so I normally do not recommend them.  

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Jim Hyland


30 years experiance in the ID and management of forest diseases and ID of landscape tree diseases.

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