WALNUTS
IN A NUTSHELL
Black Walnuts
The Eastern Black Walnut, Juglans nigra, is appreciated as a shade tree as well as for its distinctively flavored nutmeats and beautiful wood. The tree occurs naturally from southern Canada to the Carolinas and west to Iowa, Nebraska, and Kansas.
Nuts or Wood?
While any black walnut tree can produce nuts, growing trees specifically for nut production differs dramatically from growing for high quality timber. Trees in the nut orchard have short trunks and wide spreading branches: all of the leaf energy is channeled into producing nuts rather than wood. Improved cultivars which produce nuts with a high percentage of kernel (20-30% as compared with ~6% from wild trees) that crack out into large pieces are grafted to wild or improved stock.
General Production Notes:
The best walnut production sites have deep, well-drained, fertile soils. Plantings are generally made on a 40'X40' spacing, although some growers recommend 60'X60'. There are many cultivars available from commercial nurseries or, for those who can graft, as scionwood from other growers. These improved varieties crack more easily and produce larger pieces of kernel with less picking. It takes less time to bring improved cultivars into production than wild seedlings but plan on a minimum of 10 years from planting to a significant harvest.
Black walnut trees are subject to late summer anthracnose outbreaks which may reduce nutmeat quality. Some insects cause damage, particularly the fall web worm and the walnut caterpillar, although chemical control is seldom required. Young trees left unprotected may be damaged when they are browsed or rubbed by deer.
One or two trees will provide a family with a generous supply of nutmeats: a single vigorous tree may produce 150 pounds of nuts in one season. If you are considering a commercial venture using hand labor to harvest nuts, you should probably limit your orchard to a maximum of 10 acres. An orchard can produce 1-2,000 pounds of hulled nuts per acre (that means you'll be picking up approximately 3-6,000 pounds of nuts WITH hulls!). Averaging 500 pounds per day (a half acre or less when trees are in full production), your fall will be spent gathering nuts. If you decide to plant several different cultivars, plant them together in blocks: the commercial buyers want lots that contain a single variety.
Harvest Equipment Needs:
Gloved hands, five gallon buckets, and nut wizards (a rolling wire basket) suffice for small orchards. It will take a 50+ acre orchard to justify the economics of purchasing a mechanical harvester unless you can find other growers who will share the cost and use of a machine. Some mechanically-inclined growers have modified a small pecan harvester which sweeps up nuts that have fallen. A tree shaker speeds harvest. Walnut hulls should be removed immediately after harvest to reduce the possibility of darkening the kernel. It doesn't take long for the green hulls to become a black gooey mess. If you are selling the nuts to a commercial processor, they will probably have a huller on site. If you opt not to sell the nuts to a commercial buyer, hullers will generally process them for you at a modest cost. If you have your own equipment, hulling can be done in your orchard as you harvest the easiest way to quickly dispose of the hulls.
Markets:
Hammons Products Company of Stockton, Missouri is the largest (and the only) significant commercial buyer and seller of black walnuts. Most of the nuts they sell are gathered from wild trees by individuals who transport them to hulling sites in a multi-state area. They are paid according to the final, hulled weight of the nuts brought in. Hammons pays a premium for nuts from the improved cultivars but these must be transported to their Stockton facility. In addition to nutmeats, Hammons also sells the ground shell which is used in cosmetics, as well in industrial applications.
Fair Warning:
No commercial operation should be undertaken without a thorough understanding of the potential threat of Thousand Cankers Disease, a fungal infection spread by a small beetle which has decimated black walnuts planted in the western United States. It was identified in black walnuts in Knoxville, TN in July, 2010, in Richmond, VA in July, 2011, and in Buck County (north Philadelphia), PA in August, 2011. This disease has the potential for decimating both wild and cultivated trees, much like Dutch elm disease and chestnut blight.
Professionals from many scientific fields as well as black walnut growers met in Lafayette, Indiana in mid-June, 2017 to reassess the threat of Thousand Cankers Disease. The consensus was that, although TCD remains a serious threat to black walnut trees grown in the West, there was room for cautious optimism that the disease would not have similar devastating affects on black walnuts growing in their native range.
Resources:
The following resources are available on line. Our spring and fall MNGA meetings are held at nut orchards and provide an opportunity to see various practices in action.
Flowering and Fruit Characteristics of Black Walnuts
US Forest Service Thousand Cankers Pest Alert
How to Diagnose Black Walnut Damage
Growing Black Walnuts for Nut Production
(includes information on Walnut site suitability in MO)
USDA:Forest Service/Purdue/Walnut Council Thousand Cankers Disease Information Sheet
July 2020 Black Walnuts