Walnut trees are beautiful, tall trees that offer a lot of shade and character to a lawn or garden. They also produce walnuts encased in black shells. If you don't eat walnuts, this can be a nuisance. The walnuts can cause damage when they fall and will attract animals such as squirrels.
Trim branches that you can reach in late fall, a few months after walnuts have fallen. The tree normally will set the bud locations for the next year's nut production a short time after harvest. Cutting these limbs will put the tree's energy into regrowth instead of producing fruit.
Apply a fruit reduction chemical to the tree. Spray it on the branches and leaves. Try to get it on as much of the tree as possible. This spray should be applied in late spring before the nuts start to form.
Add nitrogen to the area around the tree. According to Jerry Parsons, Ph.D., with the Texas Agricultural Extension of San Antonio, large amounts of nitrogen stimulate leaf and limb growth and lower nut production for the tree. Apply it to the soil in spring each year when the walnut tree would normally set buds and again in summer.