The fruit, leaves and roots of black walnut trees contain a chemical, juglone, that can injure other plants. Ingesting even a small amount of pure juglone can cause a serious poisoning effect in humans.

Black walnuts have higher levels of antioxidants, polyunsaturated fatty acids, and other health-promoting compounds than the more common English walnuts, making them useful in reducing the risk of cancer, heart disease, and diabetes.

Taking too much tannin can cause stomach upset and kidney and liver damage. The bark is POSSIBLY UNSAFE. Taking the bark daily might increase the risk for tongue or lip cancer. When applied to the skin: Black walnut is POSSIBLY UNSAFE.

Source of Toxicity Black walnuts produce a chemical called juglone, which occurs naturally in all parts of the tree, especially in the buds, nut hulls, and roots. Because decaying roots can release juglone, toxicity may occur for several years after a tree has been removed.

Well, the Black Walnut was in fact part of many native American diets but most of the walnuts we eat today are actually English walnuts, which have a milder taste and broader appeal. They also have thinner, easier-to-crack shells. Black Walnuts on the other hand have a bolder, earthier flavor.

Husks of fallen walnuts can become toxic to livestock, and lethal to dogs if ingested due to a mycotoxin called ‘Penitrim A’, which is produced by Penicillium mould.

A pitted shell encases a fibrous, leather sheath that splits as the nuts begin to ripen in the fall and indicates that walnut tree harvesting is nigh. Once you are done harvesting the walnuts, you can eat them right away, but keep in mind they won’t be quite like those purchased ones at the grocers.

The juglone toxin occurs in the leaves, bark and wood of walnut, but these contain lower concentrations than in the roots. Walnut leaves can be composted because the toxin breaks down when exposed to air, water and bacteria. The toxic effect can be degraded in two to four weeks.

Black walnut shavings are a toxic bedding for horses. The innermost wood of the black walnut causes toxicity after oral or skin contact. Bedding containing as little as 20 percent fresh black walnut shavings made from old or new wood can cause toxicity.

Leaves, bark, or wood chips of black walnut should not be used to mulch sensitive landscape or garden plants. Even after a period of composting, such refuse may release small amounts of juglone.

Black walnut tree compatible plants are any known plants that grow under black walnut trees without any sign of toxicity damage. Black walnut tolerant plants include the sugar maple, flowering dogwood and the boxelder to name a few. You can also plant crocuses, hyacinths and begonias.

Black walnuts are one of the most flavorful nuts for snacking, baking, and cooking. These hard-shelled fruits have a sweet, delicate walnut flavor and are one of the most expensive nuts on the market.

Black Walnut Toxicity (Juglone) But black walnut trees are not always good companions in the garden and yard. In fact, they can be toxic to nearby plants. Very often, when sensitive plants are grown near the roots of black walnut trees, the plants die.

Avoid planting tomatoes within the spread of a walnut tree’s root system (two to three times the circumference of its branches) or plant them at least 50 feet away. Don’t plant tomatoes for at least two years in locations where these trees may have grown before.

Tomatoes may grow successfully in the vicinity of a black walnut tree for a while. Yet as the tree and its root system grows, it will eventually reach the garden. Symptoms of walnut wilt are sudden and dramatic.

Walnut leaves can be composted because the juglone toxin breaks down when exposed to air, water and bacteria. However, composting the woodchips for a minimum of six months allows the chemical to break down to a safe level even for plants sensitive to juglone.