I have developed a problem with my Autumn Blaze Maple and have included a...

Asked August 27, 2013, 2:00 PM EDT

I have developed a problem with my Autumn Blaze Maple and have included a picture. I live in southern Minnesota and planted the tree in the spring of 2010. It has done very well up until this point. About 3 or 4 weeks ago, the leaves on two braches coming off the trunk, have wilted and dried up. This started in late July or early Aug. Each year I have done some minor pruning to keep its shape by pruning off the ends of some branches. I usually trim it at the end of the season or in spring before it starts to bud but I did do some minor trimming this year during the growing season. Our weather this year was cool and wet in the spring and now dryer and hotter but I do water when needed. Each spring I fertilize by poking small holes in the ground around the perimeter of the tree and adding 10-10-10 fertilizer into the holes (not sure how much total fertilizer I use but much less than 5 pounds). I have looked at the leaves and do not see any bugs/mites etc. My thought is to just leave it alone for the rest of this growing season and see how it looks next season. If there is some reason to cut off these branches to keep the problem from spreading, I would do that but it would significantly diminish the uniform look of the tree. If there is any other info. that would be helpful, please let me know and I can add that. I love this tree and want to save it but am not sure what is wrong or what to do about it. Any help would be greatly appreciated. Thanks.

Freeborn County Minnesota maple trees dead branches

4 Responses

I'm sorry to see this kind of damage on your beautiful maple. A number of things could cause this type of die-back, and at some point you may want to call in a certified arborist to make a careful inspection, but in the meantime here are some things you may be able to do to identify the cause:

Do you see any signs of insect activity on this branch, or on the trunk on that side of the tree? Activity such as holes in the bark? Wood boring insects can cause this kind of damage, and/or they can kill the tree - either through their own activity that causes tissue death under the bark, or by opening the protective bark layer to bacterial or fungal disease. Some insects can be controlled with pesticides, some are much harder to control. Here is a link about these pests:
http://ianrpubs.unl.edu/live/ec1580/build/ec1580.pdf

When you scratch open the bark on the affected branch can you see moist, greenish wood, or is it dry?
Do the twigs on this branch snap off, or are they still nicely pliable? Maples are subject to verticillium wilt which can cause the death of the whole tree. If the cambium shows sort of olive/grey streaks when the bark is peeled back this might be the problem, but it would take a lab test to make sure. Here is a fact sheet about this disease:
http://www.extension.umn.edu/distribution/horticulture/DG1164.html

What do the roots on that side of the tree look like? (you may have to carefully remove some of the soil at the flare to see them). If there is/are roots that seem to be circling around the trunk, rather than growing straight out away from the trunk they may be choking off the circulation of water and nutrients. Here is a link about root girdling. This is one page of a long discussion about this problem. I encourage you to look over the whole publication:
http://www.extension.umn.edu/distribution/naturalresources/components/7501_06.html

Finally, here is a link that will help you find an arborist, if it seems like that would be the next best step:
http://www.extension.umn.edu/distribution/horticulture/M1315.html

I hope this information is helpful. Please contact AaE again if you have further questions.

Mary, I just wanted to follow up on this issue. The branches are still green and pliable. No holes in the tree trunk noted. What I did notice upon close inspection is that the leaves, both wilted and healthy, have lots of very tiny little black bugs/mites? They are smaller than bits of pepper, very hard to see with the naked eye but are all over most of the leaves I looked at. Is it possible these little bugs/mites are causing the problem? See photo included. Thanks again.

Thanks for the additional information. The insects that you are seeing (if they are insects..this could be a sooty mold, too), are very unlikely to cause the damage we are seeing in this tree. Although this kind of "infection" and the insect activity that goes along with it can cause problems, the usual signs affect the whole tree - not just one branch. Here is a link to some photos and explanation of sooty mold:
http://www.extension.umn.edu/projects/yardandgarden/ygbriefs/p440sootymold.html

If you have eliminated most of the other symptoms I urge you to consider verticillium wilt as the most likely reason for that branch die-back. A certified arborist will be able to accurately diagnose the problem and offer treatments, if possible.

Thanks again Mary C. I suspect your thought of verticillium wilt is probably correct. I plan to call a local arborist to have them come out to assess as soon as possible. Working on Labor Day?! Again, thanks.

Roger Fleegel