trunk problem with Sunset Maple

Asked June 26, 2020, 4:30 PM EDT

We have 3 Sunset Maples. All appeared to be fine. I just noticed today (only because the damage faces the neighbors) that one of them has a huge trunk split issue. We have another triple trunk maple that had a very small, somewhat similar issue when first planted (and it was 15 feet tall) but that issue seems to have gone with a minor scar. This one looks very bad. We'd like to know what it is and is there anything we can do to treat it. We have had the dots on the leaves too when it is very dry but that comes and goes. Thanks.

Allegan County Michigan

1 Response


Some trees, Sunset Maple included, have very thin bark when young. Vertical cracks in trunks are most often caused by frost cracking and sunscald in winter. Sometimes these opening are from mowers or weed whip damage, or trunk bark injured during planting. The wound will start to close, then frost cracking re-opens the wound each winter. There are things you can do to help the wound completely close.

You can help by giving it water during droughts, like the one we have had this past month. Trees need about 1 inch of water per week throughout their root zone, when soil is dry in the top 2-4 inches.

Mulch in a circle around the tree, keeping mulch no deeper than 3-4 inches and mulch pulled back from the trunk several inches so it does not touch bark. This removes competition for water with other plants and grass. It also removes the need to use a mower or weed whip near the trunk. Hand weed the area only. Mulch against the trunk can cause bark to rot. I see you have used stone mulch. This too should be kept back several inches.

The tree was planted too deeply in the soil. A certified arborist has the special tools to excavate the root collar, where the main roots branch from the trunk. This will improve the health of the tree and likely extend its life.Root zone aeration and spring fertilization also helps. Find certified arborists by zipcode here –

In late fall use a paper, pierced plastic, or burlap tree wrap on the trunk. This shades the trunk keeping it cool to help prevent sunscald and frost cracks. Remove the tree wrap each spring, and replace it in fall. After 5-7 years the bark will probably be thick enough to stop wrapping it.

Here are references for you-

Young tree care, and planting depth/root collar—-

Winter protection-

Frost cracks and tree care afterward—

The spots on the leaves may be galls.These are harmless to the tree

Later in the summer you may see tar spot develop, which infects the leaves in early spring. It , too, is cosmetic and doesn’t harm the tree.

I hope this helps keep your trees healthy.