Q. I have a 6-8 yr. old ash that has this white powdery looking substance on the newer growth. Can you tell me what it is and how to eliminate it.
|Picture from reader of white growth on ash|
A. I have seen this kind of "growth" on several vegetables and herbs as well including peppers and basil over the years. I have sent pictures of these two a good friend of mine, a well-known horticulturist in Arizona asking him what he thought they were. I could tell he was giving me his best guess as well but I don't think he was very sure himself.
Here is a post on something similar I made back in 2012
Although not exactly the same thing it appears to be more insect related than disease or physiological in nature. I wish I could give you a better response than just to keep your eye on it and let me know if things get worse. If things do get worse, then I would direct you towards a soil applied systemic insecticide for the tree if it is needed. That is the best I can do for you at this point.
Perhaps some are other readers might hazard a guess?