I am sorry for this delayed reply to your gardening question. The spring rush has brought a deluge of questions and we are working hard to catch up!
Oaks do get a powdery mildew on the foliage and burr oaks are definitely susceptible. But the disease doesn't pose a bit threat to the tree and they survive and grow just fine with it. Burr is a native tree to your area and so I wouldn't worry about it. If you want to spray to control it I suggest sprays of either potassium bicarbonate, or neem oil, or bayleton every 10-14 days for 2 or 3 sprays. Then when it comes back later in the season be ready to spray once or twice again.
Thanks for the question. Best wishes for a wonderful gardening season. Please stop in again soon!
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