I have a red Acer tree (about six years old)up the trunk there are signs of white power with brown spots. I have brushed them off and my tree appears to be healthy. What could this be?

  • Hard to tell from only your description, white powder, brown spots... Can you brush the brown spots off? Do you have a picture of it?
    – benn
    Jul 6, 2018 at 16:46
  • Round here, acer bark likes to crack in spirals around the trunk due to winds. That makes a lovely avenue for infection. Oct 5, 2018 at 15:17

1 Answer 1


Probably horse chestnut scale by the sound of it, which is common on Acer, particularly Acer palmatum varieties. If the tree is very large, its usually not possible to treat, but it seems not to kill the tree anyway. On smaller trees, its relatively easy to deal with because its on the woody parts - its not uncommon to find it also on the pot (if its potted) or on a wooden fence behind the tree. I just use disposable cloths lightly moistened in methylated spirits to rub them off, then wipe over the treated parts with a wet (with water) cloth afterwards. Info and image here https://www.rhs.org.uk/advice/profile?PID=650

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.