I just bought a house with a beautiful garden, but neglected. I see the palm fronds and some other trees have what looks like dry, white powdery areas on the leaves. The camellias have gray or black spots and the leaves are discolored. The garden has been abandoned for several months. I'd love to make it beautiful again!
Whte Powder on Palms and Other Trees
Certified GKH Gardening Expert
This is powdery mildew. Here is an article or two that you may find helpful: https://www.gardeningknowhow.com/problems/get-the-cure-for-powdery-mildew.htm
You can also try using neem oil to treat the plants.