Sick Apple Trees
For the last two to three years the Apple trees in our yard start out in the spring with blossoms. They appear to leaf out then all of the leave yellow and fall off by early to mid summer. By early fall the stArt to be leaves again and even a few blossoms. Some one suggest apple scab but there is rarely any fruit. Please help
St. Mary's County Maryland
Both apple scab and apple rust will cause leaf drop and defoliation. Both also cause the fruit to fall when immature. Yours may never get a chance to develop significantly.
In order to have a good apple crop, you will have to follow a spray schedule. Here is our apple page:http://extension.umd.edu/hgic/topics/apples Go to Apple Problems > Diseases, then to Scab or Rust. There are links to spray schedules.
Repeated years of defoliation will eventually kill your tree. Replant with a highly disease resistant variety.