Bears, like many people, love to taste the ripe, tender fruit of plum trees. Drawn by their keen sense of smell, bears can smell ripe fruit from miles away. During the late summer, as bears prepare to hibernate, they'll eat just about anything and everything they can get their paws on. Protecting your fruit trees from bears offers special challenges to homeowners and gardeners, but it can be done in a way that protects both the bears and their human neighbors.
Erect fences around your plum trees or orchard. Depending on your location, and the determination of the bear, picket fences or chain link fences placed around the trunks or span of your fruit trees or orchard may be enough to deter most of them. However, large bears such as grizzly bears or those that are especially hungry may simply knock down such fences.
Place a large square of livestock fencing around the base and under the umbrella of your plum trees. Most animals don't like to walk on wire fencing or grates and will back away from them. Attach and secure the fencing to the ground around the tree with stakes. Livestock wire fencing can be purchased at most feed stores, home centers and ranch supply stores. Fencing that is 12 to 14 gauge works best and is sturdy enough to handle heavy weight.
Install alarms along a fence line or perimeter for a nonlethal solution to bears damaging fruit trees. Bears don't like noise. If you can't afford an alarm system, try hanging empty tin cans or other noisy objects from the fencing. You could also surround fruit trees and orchards with electric fencing if you live in bear country.
Throw stones at the bear. Aim at the bear's rump. Do not ever throw stones directly in the bear's face or vital organs. Stones should not be larger than a golf ball.
Toss big beach balls at the bears to scare them off. Other effective deterrents include opening and closing an umbrella, shaking a big garbage bag, or banging pots and pans together.