Hello,

It's hard for me to see what's going on from this photo. Are you able to take higher resolution photo or can you get some close-ups of the leaves/branches? What species of tree is it? Once I get some more information, I would be happy to assist you.

Thanks,

Lorelle

Hi there,

Please feel free to send photos to <personal data hidden>. I will likely need closer photos of the leaves/needles to diagnose what's going on. It's often hard to do so from afar.  Do you know what species of tree this is? Where are you located (generally)?

Hi there,

The good news is- this is powdery mildew and is not too concerning! We are seeing a massive surge in powdery mildew in our region (not just on maples, but several hardwood species) likely because of the prolonged cold and wet spring we had. The powdery mildew may inhibit photosynthesis a bit this year, but it will not impact the overall health of the tree. If the leaves start turning brown and falling off, the tree likely has anthracnose, a common fungus disease in maples. Again, the cool, wet weather we had this spring has encouraged fungal growth. If you do notice anthracnose, it would be wise to rake and destroy fallen leaves as they can harbor the fungus overwinter allowing reinfection next year. It it’s just powdery mildew (that’s all I’m noticing), I would recommend waiting until next year to see if the tree is reinfected. If a maple tree is re-infected year after year after year, it may stress the tree out, but one year is not a big threat.

Maple powdery mildew info and treatment (though you don’t need to treat it): https://pnwhandbooks.org/plantdisease/host-disease/maple-acer-spp-powdery-mildew

Anthracnose info and treatment: https://pnwhandbooks.org/plantdisease/host-disease/maple-acer-spp-anthracnose