will powdery mildew kill my trees?

I have a tamukeyama...bloodgood...and kamagata all planted this year. All are infected with powdery mildew with tamukeyama being the worst. Will it kill them? What can I do? I live in Ny zone 6. Any help will be appreciated.

 

Hello,

This season is by far the worse for disease in my area and the NE US. It's due to high humidity and all the rain we had in the first half of the season.

The powdery mildew will not kill your trees (unless they were already struggling to live before the outbreak), but if left untreated it will cause them to defoliate. I use Bayer advanced disease control to treat powdery mildew, but its not for sale in NY. I would go to a local garden center and buy a disease control spray to treat your maples. Also, I would avoid evening over-head watering. Try to avoid getting the leaves wet when watering.

The varieties of maples you listed typically don't have problems with powdery mildew (with the exception of this season). If we have a "normal" season next year and the problem continues to persists, then consider moving the trees to an area that gets more air movement and sun. But keep in mind this season is awful for disease outbreaks, so more than likely it will not be a problem next year.

 

Many mildews become conspicuous in summer because there is some dry weather but leaves may still be dampened, especially at night. The spores need dry conditions to blow around in and a moist leaf surface to germinate on. If the leaf is instead dry on the outside or being washed by downpours at the time of sporulation that is not favorable for mildew development. You can actually inhibit mildews somewhat by washing plants off with water - but not, of course during conditions when the plants will then stay wet for a long time afterward.

With Japanese maples specifically you also do not want these to be subjected to cool and wet conditions in the fall as this encourages bacterial blight.

 

This year has been awful. My tomatoes all cracked and rotted. I hope the trees survive and next year is better. Now I have to worry about the winter winds.