I have an ornamental cherry (I think it is called a Maytree or May Cherry) that was planted about 6 years ago. It seems quite robust every Spring and has grown to nearly 18-feet in height. The problem is that many leaves are turning now, becoming red and dropping off in early July. For the past two years, a large colony of aphids attacks it in April. I respond with lady bugs and am assisted by a fleet of Wilson's warbler; who pick the tree quite thoroughly for a week, before migrating off. I also note that, on occasion, sap oozes from the trunk near to where it meets the soil. The soil is clay, but the original planting went deep, so that (I think) the drainage is okay -- reaching to a layer of sand underneath near lake level. Should I be doing something for the tree? Is this merely an aphid problem that the tree will eventually conquer or is something more nefarious involved?
I'm sorry, I can't answer your query. I'm just trying to keep things organized here. The term "May Cherry" seems to be used for Amelanchier, not actually a cherry. And I see that "maytree" is a term used for Hawthorn (Crataegus mongyna). If you're writing about an actual cherry, you're in the right place. Otherwise, I could move this posting to Outdoor Gardening in the Pac Northwest, which might get more coverage for you. Presumably, the answer would be the same whatever the tree is. Still, if you could post a few photos (and include one of the flowers if you have it), I'd appreciate that, so we can keep the names straight in the cherry forum and maybe help you get the right response (if someone knows the answer to your question).
It is not a hawthorn. It is some kind of cherry: The leaves and bark look like cherry and there are small black fruit. I'll investigate further; but I think the post is in the right place. Thanks! (I'll get some photos.)
Probably Prunus padus, otherwise similar P. virginiana is often planted. With the latter in particular you might be having some problems with impeded soil drainage and root rot. Otherwise scattered dying back of twigs could be bacterial.