Black walnut is highly prized for its wood, which is used to manufacture
furniture, wood paneling and veneer and gunstocks. While the fruit of
the tree provides food for people and wildlife, the outer hulls have
been used for centuries to make tinctures and infusions to address tinea
infections of the skin (i.e., ringworm) and for use as an internal
vermifuge.
The active compound in black walnut is juglone
(5-hydroxy-alphanapthaquinone), which occurs in all parts of the tree.
Crushed shells on the ground or contamination in bedding material can
produce allergic reactions in horses. Black walnut hulls are also toxic
to fish. In fact, Native Americans would toss the hulls into a body of
water to stun the fish, making them easy to catch.
Black walnut hulls are also used in several industries. During World War
I, they were used like sand blast to clean airplane pistons. The hulls
are still used today as a filler in dynamite, as a non-slip agent in
tires, and as an additive in products used to clean jet engines. The
crushed shells are also found in paint strippers and in certain
insecticides.
