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   Nov 14

Black walnut trees may be messy, but they have their uses

As a child, I was forced with a specific chore in mid-fall. My mother would hand me a five-gallon bucket and direct me to the walnut trees that lined our gravel driveway, instructing me to gather the fallen nuts that were still encased within their green husks.

I would return home, my fingers stained black from the cracked, crumbling hulls, unable to get the smell of this retched nut out of my sinuses for the next few days. Of course, I now know that a chemical called juglone was the root of the smell. Juglone is present in the meaty outer hulls that cover the walnuts. But now, as an adult, the smell doesn’t seem to bother me at all- as I suppose it’s a nostalgic reminder of foraging for useful things that flank our doorsteps.

Native black walnut trees (juglans nigra) are abundant in North Carolina, and can be found all over the East coast from New England to Florida. A large, upright tree, the black walnut can grow 50 to 75 feet tall with a large canopy. It does best in full sun, but is often seen in wooded areas where it grows tall and devoid of low branches. They prefer moist, well-drained soil. The round green nuts ripen in September, fall to the ground and can be harvested throughout the fall.

For a number of reasons, black walnuts are not a tree that are sought for their landscape value. The most obvious and resound reason is their messy fruit. When the large fruit drops in fall, they create a mess in the yard. When the green husks open, they can stain whatever they touch — patios, driveways, and lawn furniture. The nuts are heavy and crumbly, making them difficult to remove from the lawn. Black walnuts are also one of the last trees to leaf out in the spring and one of the first trees to lose their leaves in the fall.

Perhaps the most practical reason black walnuts aren’t utilized in the landscape is because of their toxicity to other plants. The roots of the tree — as well as leaves and husks — produce juglone, and that chemical can kill or stunt the growth of surrounding plants. This is usually limited to the dripline of the tree, but can be present in the soil wherever nuts have fallen and decomposed.

If you choose to incorporate the native black walnut tree into your landscape, keep in mind that it has many companion plants that tolerate its toxicity, including elm, hickory, persimmon and pawpaw.

So we have all these reasons to steer clear of black walnuts, but what about the beneficial qualities of this tree? There are many uses for black walnut fruit — some practical in our backyards, and some working on a global level.

Black walnuts are an abundant and nutritious food source. They’re a good source of protein, fiber and omega-3 fats. Although I’ve never been a fan of their flavor, most everyone I know enjoys eating black walnuts. Harvesting the nuts and hulling them can be a messy chore, though — one that most people don’t take the time for. The buckets of walnuts I brought home as a child were hulled and cracked in our driveway with gloved hands and hammers, and the finished product used in holiday baking.

Black walnuts serve a number of herbal uses — in traditional medicine and modern herbal remedies. In the 18th and 19th centuries, black walnut husks were used to treat a number of internal and external ailments, including ringworm, skin yeast infections, and gastrointestinal problems. Modern day herbalists use black walnut to make tinctures and powders for fungal infections, such as athlete’s foot.

Black walnut shells serve several purposes in industrial applications, including water filtration and abrasive cleaning.

For example, Hammons Products Company is a large Missouri-based processor of black walnuts. In addition to processing, packaging and distributing black walnut meat, Hammons also grinds the shells for industrial purposes.

When used in water filtration applications, black walnut shells help to separate suspended particles (such as oil) from water. Using the shells as a filter media is both sustainable and long-lasting. When used for abrasive cleaning, ground walnut shells are used in the same manner as sandblasting. The walnut particles are not as harsh as sand, and are often used in historic restoration for removing paint from wood, brick and sheet metal.

From a personal gardening perspective, I see black walnut trees as a valuable native tree — one that plays host to insects that fuel our local bird population. When kept on the outer limits of our yards, these trees serve a great function in our ecosystem, providing us and wildlife with food.

Source: Winston-Salem Journal

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