Red Oak Disease

Asked May 31, 2020, 4:43 PM EDT

We have a red oak that was planted as an acorn approximately 20 years ago. We noticed small yellow spots on several leaves. We also have reddish leaves at the tips of the higher branches. We are wondering what is causing the damage and if it is treatable. These pictures were taken 5/31/2020

Macomb County Michigan

1 Response

Hello,

Thank you for your pictures!

The yellow spots on the leaves look like oak leaf blister. If you see that they are raised a bit then this is the likely cause. Leaf drop does occur with this. The holes within the some of the leaves could be the result of the shot hole leaf miner. Both issues don’t cause any real harm to your tree and no treatment is necessary.

More information:

http://plantclinic.cornell.edu/factsheets/oakleafblister.pdf

https://bygl.osu.edu/node/1576

The leaves that are reddish looking on the higher branches is interesting. I believe this is due to weather conditions when those leaves were leafing out. The summer like conditions we had followed by a freeze may have stopped the green pigment from fully developing. An excerpt from the below article explains:

…” In 2002, for example, an early April heat wave triggered rapid leaf and flower development,” said Wilmot. But it was spring, after all; the heat wave faded and cold air returned. “Leaf development stalled and the partially emerged leaves had to withstand several weeks of cold.” This can be very dangerous for tender young leaves, and, as it turns out, it might explain those springs when there is more red than green in the canopy. And, get this: all that red may actually help protect those vulnerable young leaves.

Hardwood leaves are normally tinged with some red when they first appear. Gradually, they appear more greenish as they produce the all-important green pigment, chlorophyll. But this requires light and warmth. If those newly emerged leaves are greeted by a cold snap or prolonged cloud cover, they cannot make chlorophyll and will remain reddish for an extended period.”

The following link includes the full article.

https://northernwoodlands.org/articles/article/why_do_leaves_in_spring_sometimes_appear_more_red_than_green

The picture of the truck is one of concern. There are many things like borers, cankers and other types of bacteria that can display this type of wound. I can’t make a determination from the picture. Therefore I am recommending an onsite analysis from a certified arborist as soon as possible. This is the time of year that oak wilt can begin and I would hate to see this progress into that.

A certified arborist can found in your area by using your zip code from the ISA (International Society of Arborists) website. Make sure your selection states certifiedthey are the ones that have the proper credentials and education for tree diseases.

https://www.treesaregood.org/

https://www.treesaregood.org/findanarborist

I am also providing additional information on oak wilt.

https://www.canr.msu.edu/news/understanding_oak_wilt

https://www.canr.msu.edu/news/oak_wilt_disease_1

For future reference on other oak tree problems:

http://www.missouribotanicalgarden.org/Portals/0/Gardening/Gardening%20Help/Visual%20Guides/Oak%20Problems.pdf

http://www.uky.edu/Ag/Entomology/treepestguide/oak.html

If you have any further questions don't hesitate to contact AaE again.