That's annoying I had the same with the cherries. Last year nothing the tree was sick I though it would die. Seems to be a cherry tree issue. The year before that I covered the part of the tree and had plenty. One I tried the cd hang in the tree trick but that didn't work. The birds are very brutal and reign the world. If you pick them green they won't ripe? I did it with tomatoes that worked well, although it was fine if they remained green for green curry.