Q.Amalanka With White Spots
We planted this beautiful mature Amalanka about 5 years in a London garden with fairy good irrigation in a clay based soil. After the second year, white fungus like spots appeared on all leaves and on the top branches. I have treated the tree with fungicide the past two years but have seen no results. I have not seen any insects on or around it. The new leaves grow with the spots from the start every year. I am attaching a couple of picture for your information. Can it be Phosphate deficiency or something else? Could you please advise your opinion?
Certified GKH Gardening Expert
It looks like powdery mildew, a common problem with ornamentals. You also may have some leaf spot fungus mixed in. The thing about fungicides is they are more effective as a preventative than a solution. Is this a serviceberry? I didn't find a tree with your exact spelling. They are in the rose family and have some of the same problems. Do you have the tree in full sun? That is the best situation for serviceberries. Also, picking up and discarding fallen leaves will discourage the fungi from overwintering.
Here are some articles that may help: