Question of the Week – Number 2: April 23, 2020

“What is wrong with my live oak? This has developed in the past couple of weeks.”

This is oak leaf blister, and it’s been the topic of about half the questions people have been asking me.

It is a fungal issue that shows up on new growth in the spring. But the good thing is that it’s not especially harmful in the long term. These affected leaves will soon fall to the ground and new, healthy leaves will replace them. Soon the affected trees will look fine again.

At this point there isn’t any real call to action. If you were going to spray for this disease, you’d have to do so as the buds were just emerging in March.

Oh, and I’ve also had questions about it affecting Shumard red oaks – it’s definitely not reserved just for live oaks.

When I want really reliable web searches I always include the word “university” at the beginning of my key words. That gets me out of the blogs and public opinion discussion groups and into real science. If you Google “university plant pathology oak leaf blister” you’ll find it on a dozen or more university websites.

Having done that, here is what Texas A&M has to say about oak leaf blister.