Our oak tree prune

Asked July 24, 2019, 11:15 AM EDT

Trimmed our oak tree, exposed a hollow branch leading to the trunk, should this be plugged up? Is this a problem for the tree??

Itasca County Minnesota

1 Response

We no longer normally recommend any sealing of wounds or cuts as studies have shown that sealing seals in pathogens and the tree does a lot better job of sealing its wounds than anything we can buy.

Oak wilt is a big problem this time of year and pruning oaks is not recommended, but if any damage occurs use of a tree sealer is recommended. However, oak wilt has not been reported in our area yet (See https://extension.umn.edu/plant-diseases/oak-wilt-minnesota). This does not mean that it isn't around, it just hasn't been reported yet and the map shows it is getting very close. So, you should avoid pruning April-July when the risk is high. See https://www.dnr.state.mn.us/treecare/forest_health/oakwilt/index.html

If it is just a branch that is hollow, you can cut it off flush with the tree. See https://extension.umn.edu/planting-and-growing-guides/pruning-trees-and-shrubs. If the trunk has started to rot (is hollow), the tree may be in trouble. If the hole is into the trunk you may want to consult a certified arborist to see if the tree is in danger of coming down (https://www.treesaregood.org/findanarborist/findanarborist)

See https://www.mortonarb.org/trees-plants/tree-and-plant-advice/horticulture-care/trunk-wounds-and-decay for more info on tree cavities.

Good luck with this.