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WALNUT TREES CAUSE OF GREATEST NUMBER OF QUERIES
Of the hundreds of gardening calls I receive each year, the plant most asked about is the walnut tree.
Questions range from planting walnuts as an investment, harvesting and drying nuts for food, husking and cracking the rock-hard shells, extracting the dyes, and concerns about the toxic "juglone" given off by the plant.
Walnut trees were cultivated in ancient Babylon. Petrified walnuts were found on the table at the Temple of Isis in Pompeii. The Greeks knew the tree as "Persian nut" and the Romans as "Jupiter's acorn."
Ever wonder why we call someone a "nut?" The head-like shape of the walnut led to the nineteenth century use of the word "nut" to mean head, and the accompanying "off one's nut" to mean crazy. Later, the expression "to use one's nut" referred to thinking, "nuts" came to mean cuckoo, which led to "nut case," and these people sometimes ended up in a "nut house."
The two species most familiar to Minnesotans are black walnut (Juglans nigra) and butternut (Juglans cinerea). Interestingly, nearly all packaged walnuts are English walnuts grown in California.
Black walnuts can grow to over 100 feet with a crown nearly as wide. They prefer deep, rich, moist soil and develop an extensive taproot that makes transplanting difficult.
Black walnut wood is harder than oak and extremely stable once seasoned. Historically, black walnut wood has been popular for furniture and was the wood of choice for gunstocks because of its resistance to warping. It's been the wood of war, supplying gunstocks for Revolutionary war muskets and Winchester repeating rifles used in the war on buffaloes. In World War I, black walnut wood was used for airplane propellers.
The extraordinary toughness of the black walnut shell is the major reason it has not had the commercial success of its English cousin. Separating the nut from its fleshy husk can be a challenge. Naturalist Euell Gibbons recommended stomping nuts wearing heavy boots, while some walnut growers drive their pickup trucks slowly back and forth over rows of nuts. Some years back the USDA suggested using corn shellers to remove husks.
Whatever your method of husking, beware of the dye in the husks. A Swiss naturalist visiting the American colonies wrote in 1751: "The green peel yields a black color which could not be got off the fingers in two or three weeks time, even though the hands were washed ever so much."
I remember storing walnuts and butternuts on the south-facing sloped roof of our granary. The fleshy green fruit (anatomically similar to peaches and plums) gradually shriveled and turned dark brown. If memory serves, our methods of husking and cracking involved hammers and the workshop vice. Whatever we didn't eat while cracking, mother added to cookies and other treats.
The butternut's name is most likely attributable to the kernel's high (60%) oil content. Settlers used butternuts to polish furniture, advising that "a single nut kernel is sufficient to thoroughly oil one walking stick."
The butternut's brown dye colored the uniforms of Confederate soldiers a tan closely akin to the modern khaki, which led the Yankees to nickname the troops "butternuts."
The brown pigment in black walnut is called juglone. Exuded into the environment, juglone is toxic to microorganisms, fungi, insects, fish and even some mammals. Sensitive species attempting to snuggle up to a walnut tree are soon afflicted by "walnut wilt" - a slick way of maintaining personal space.
The most sensitive plant seems to be tomato, but other plants that can be affected are alfalfa, apples, asparagus, chrysanthemums, honeysuckle, peonies, potatoes, rhododendrons and roses. Resistant plants include hollyhocks, bellflowers, bee balm, Jerusalem artichokes, snowdrops, grape hyacinths, weeping forsythia, Virginia creeper, begonias, marigolds and pansies.
If you've planted black walnut trees to pay for your retirement, plan to live a long time. A healthy walnut may stand for two or three centuries. The Colbert Ferry Walnut in Alabama marks the site of the ferry that connected the Natchez Trace with the Tennessee River. It still stands and has a girth of 14-1/2 feet and a height of 78 feet. The largest walnut tree in the U.S., towering more than 138 feet, is in California. Minnesota's largest black walnut is in Olmsted County and has a girth of 13-1/4 feet.
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PUTTING DOWN ROOTS:
A Delightful Blend of
Gardening Wisdom, Wit
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by Cliff Johnson |
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