About 6 years ago I purchased a 5 ft tall Japanese Lilac tree It arrived with the top cut off so that it would fit in the 5 ft long box. I complained and to cut a long story short the company made good by supplying a non cut plant. I planted both side by side 15 feet apart and things went well until 3 years ago when the cut version developed spots on the leaves and lost its leaves 2 months earlier than the other tree. Last years the same thing happened even though I treated the trees with a copper solution specifically for black spot diseases. This year I sprayed with the copper solution when the leaves had just fully developed and at regular intervals as indicated by the instructions on the fungicide bottle, but as you can see from the attached images the tree is already infested and about to lose its leaves in early August. The other tree is now more than three times its size 18 feet tall and not affected by the black spots. I don't have to water the trees as here in Maine we get regular downpours of rain lasting 10-12 hours at a time roughly every week. Temperatures are about 80F during July cooling slightly in August to about 70F. Any help with this ongoing issue would be appreciated