Gouty oak gall

Asked May 20, 2019, 3:10 PM EDT

Our ~50 ft. tall, ~5 ft. girth (red?) oak has an extensive gall infestation up to the crown that seems to be progressing. The condition has killed several lower branches but otherwise the leaves appear healthy. The surrounding lawn has rich soil but is poorly drained with frequent standing water. We'd appreciate any suggestions of possible remedies to help save this magnificent tree. Thanks in advance.

Talbot County Maryland insect issues abiotic issues trees gouty oak gall poor drainage oak

4 Responses

The poor drainage that you mention is not good for the tree roots. This may have contributed to the lower branch dieback and not the galls but we cannot say for sure. Check the drainage and see if you can divert the water or improve the drainage conditions and this may help with the overall health of the tree. Make sure mulch is no thicker than several inches and keep away from the trunk.

There are no easy solutions for the gouty oak gall. Management options are limited and not something you can do on your own. It may be something that you will have to decide if you can live with. You would have to hire a commercial arborist with a lift truck. Galls can be pruned when they are green and just forming in the spring. Another option is to spray a dormant rate of horticultural oil when the tree is dormant before budbreak and hope it works. The eggs of a wasp are underneath the dormant buds.

Here is some information on our website and the U of Illinois on galls as well as
https://extension.umd.edu/hgic/topics/shade-tree-galls
https://web.extension.illinois.edu/ccgms/downloads/42438.pdf

Marian



Thanks for your helpful information. We'll try to improve drainage as suggested. Please let us know whether it's also worth following U of I's advice that "[a]ffected trees can be fertilized to encourage healthy growth...." given that this mature tree already has very healthy dense foliage.

PS: Please omit my name from public posting, thanks.