There is no permanent solution to this problem. Take heart, though: Commercial growers use a spray to thin fruit. These sprays reduce the crop by applying plant hormones that cause fruit drop. When they're applied during or right after bloom, the mess is negligible. A commercially available fruit preventer is Florel. The spray must be applied during bloom, and must thoroughly cover the entire tree. Ironically, when you remove the crop, the tree puts more energy into the next year's fruit buds, ensuring a big crop if you let it go. If you really don't want the fruit, you may be better off removing the trees and planting ornamental trees that produce flowers but no fruit.