Hi there! We have a maple (variety: autumn blaze) in our front yard at Dundas and dovercourt. It was planted about 7 years ago and reaches about 15 feet high. Every year it has done so well and I believe it is well established. This year it did not have many leaves. I confess I didn’t water it as much this year, relying on rain. I believe this is part of the problem and I promise to water it more next year. In the meantime, I am wondering what I can do this late in the season. Is there anything I can do to prep it for the winter?
Thank-you for contacting Toronto Master Gardeners with your question.
The Autumn Blaze maple (Acer x fremanii) is a hybrid maple between the Silver Maple (A. saccharinum) and the Red Maple (A. rubrum). The leaf shape and the tendency to grow quickly come from the Silver Maple parent and the beautiful autumn colour comes from the Red Maple. It is possible that the weak new growth of your tree was particularly susceptible to the drought conditions we experienced in Toronto over the past month. If this is the case, you simply need to ensure you water your tree deeply if the weather turns dry again over the autumn. It should come back in good form in the spring.
Autumn Blaze maples (as well as other maples) are also the victim of a variety of diseases. Some of these are cosmetic issues only; others are more serious. Your description could indicate either Anthracnose or Verticillium Wilt. Both are fairly common, and both can be serious. The articles below give good information on diagnosis and treatment. If the only problem you can identify is fewer leaves rather than any kind of leaf spotting, I would suggest working under the assumption that your tree is suffering from an environmental stress rather than a disease. When you observe it next spring, look for any tell-tale signs of an ongoing problem. Prior to embarking on a remedy, you should consult a licensed arborist for a definitive diagnosis and recommended treatment plan.
Best of luck with your tree!