My maple leaves are covered with powdery mildew even though I’ve cut back on watering. How do I get rid of it?
Powdery mildew is an unsightly white powder that takes up residence on the leaves of many plants this time of year. The good news is that it’s rarely destructive and many gardeners prefer to simply ignore it.
The arrival of powdery mildew has nothing to do with your watering habits, so changing them won't make much of a difference. Unlike the mold that grows in your basement, powdery mildew is more temperature-activated than water-activated. All it needs to grow is warm, humid weather, of which we are getting more than our fair share these days.
The best way to deal with many plant diseases, including powdery mildew, is to take steps to prevent its growth and spread. Now, there's nothing you can do about the weather, but you can ensure that your maple gets adequate air circulation by keeping it properly pruned. And since powdery mildew spores like to overwinter on plant tissue, try to make it a practice to rake up all fallen leaves and dispose of them before winter arrives. If you notice the problem early enough, you can also remove infected leaves and dispose of them in an effort to prevent the mildew from spreading.
Weeds make wonderful hosts for a variety of disease and insect problems and powdery mildew is no exception. Keeping your garden and yard weeded is a great way to keep this fungus at bay.
One way to effectively control the spread of powdery mildew is to thoroughly spray the tops and bottoms of affected leaves with water at one week intervals. This task is best done early in the day since leaving the leaves damp overnight is a recipe for attracting other disease problems.
If you have any questions or comments, please send them to me at vanessa@gardenmuse.ca.
