Apple tree trunk problem #204655 - Ask Extension

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Apple tree trunk problem #204655

Asked August 05, 2014, 7:10 AM EDT

Please tell me what this is. Is there anything we can do about it? Can it spread to other trees? This tree was planted two years ago and was flourishing until this spring when several bottom branches died. Now the trunk looks like this. The rest of the tree is green and growing, though not as vigorously as before. Thank you.

Delta County Michigan

Expert Response

This is a canker. A disease most likely white rot or black rot has killed the bark and the tissue under it. This has resulted in the black bark and the sunken appearance of the stem. The tree is still growing above the canker as shown by the enhanced bark ridges on the edge of the cut. This is because the actively growing top of the tree is unable to send nutrients down to the roots. There is no way to restore large cankers like this. The top of the tree will eventually die. Apple throw a lot of new shoots and I can see one in the picture where the tree is actively growing. Your best course of action is to cut the tree down below the canker and above one of the new shoots coming from the base of the tree. Be sure that you do not cut so far down that you cut off all the top. Be sure you cut above the graft union and you can rebuild the tree from the new shoots. You can do that now. I would paint the would with a water down interior latex paint immediately after the cut to prevent a further infection by the fungus that caused the canker.
Mark Longstroth Replied August 05, 2014, 5:06 PM EDT

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