Crab apple trees losing leaves
I have a couple of crab apple trees that look great in the spring but start to lose their leaves in mid-late June. I'm guessing it is some kind of blight but don't know what I can do about it.
Addison County Vermont
The damage to your leaves appears to be a fungus disease, most likely Cedar Apple Rust.Here is a link to a UConn fact sheet dealing with this disease: http://www.ladybug.uconn.edu/FactSheets/apple-rust-disease.php
Apples are prone to a wide variety of fungal diseases, and you may also have apple scab. The tree usually isn't too negatively impacted, even though it looks impressive! If you want to control it, there are a variety of fungicides, both conventional and organic, that you can use to reduce the infestation. Several are listed in the fact sheet.
Your best defense is cultural controls. Good air circulation will reduce fungal problems, so annual pruning is important.
Glad to be of help!