Answer: Your bing and rainier cherry trees are good choices for Seattle area gardens and they are the right companions for good pollination. If the cherries are dropping before ripening you might cut into them and look for little worms. The cherry fruit fly is common in your area and when an egg is laid in the fruit, the worm feeds on the fruit and causes it to drop. It's difficult to control the pests but your local cooperative extension office would suggest you hang a few traps in the tree to see if you can catch the adults. These traps are red and sticky so the adults get stuck on them. Aside from these insects, about the only other cause of immature fruit dropping is poor pollination. Since you have a second cherry tree, that's probably not an issue with your tree. Wish I had more ideas for you!
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