Here's how. Cut a "V" on the top edge of the board on which the limb will rest so that it doesn't slip off. Long limbs that are heavily loaded with fruit may need a prop in the center and another to support the outer part of the limb. A plastic belt-like material that is about 2 inches wide may also be used. This can be tied to a heavily loaded limb, then to a large diameter limb above for support. Where a large limb is used for support, it is good to have it supporting limbs on opposite sides so the weight is balanced.
Another solution is to wrap a tape or belt material around the tree in a spiral to prevent limbs from bending until they break. Heavy twine may be used, but it should be removed when the fruit is picked or soon after so it does not cut into the bark on the limb.
Check trees regularly, up to two times a week during the last month the fruit are maturing. You will find additional limbs that need support. Tending to the heavily loaded tree limbs will reduce the number of broken limbs and help keep a balance of the fruiting wood in your tree. Next year, prune long, weak branches back to a side branch to help prevent this problem. (Ward Upham)