White dust on oak tree leaves
We have a small stand of mature oak trees. I recently notice that many of the leaves are covered with a white dust. It hasn’t been there before that we’ve noticed and we have lived here about 15 years. I looked online and it looks like mildew front the wet Spring. Will it harm the trees Should we have them treated in some way? The trees are very large and we cannot get a photo for you.
Based on your description this sounds like you may be referring to powdery mildew but we cannot say for sure. Take a look at our photos on our website to see if this is what you are referring to. http://extension.umd.edu/hgic/powdery-mildew-trees-and-shrubs
This is a fungal disease that can hit when the weather is cool and humid. No control is necessary. Simply rake all fallen leaves in the fall.