Black walnut is one of the most valuable hardwood species native to North America. Its nuts are edible and its wood is highly prized. 1. Description The Black Walnut is confined to the Carolinian forest zone and part of the Great Lakes - St. Lawrence zone from Kingston out to Goderich, that is in Zone 6 or warmer. If protected, the tree can be grown considerably north of its natural range. The Ottawa area Chapter of SONG has compiled a list of significant successes in Eastern Ontario either plantings or natural trees. This information is contained in its Inventree file. The most notable locations for black walnut are: Richmond Village - planted trees; Manotick Village - planted trees; Woodlawn village - planted trees; Gloucester Township - National Capital Commission (NCC) Greenbelt on the Borthwick Ridge - planted trees; Chesterville - planted in park; Britannia Filtration Plant, Ottawa - planted; Williamstown village - planted near cemetery; Oak Valley on the South Nation River- Irene Woolford, a new Chapter plantation in the South Nation Conservation Authority area; Baxter Conservation Area - Rideau Valley Conservation Authority's (RVCA) "Baxter Nut Grove", supported by the Ottawa Area Chapter of SONG; Wolfe Island - Bob Scally, planted; White Lake area - George Truscott, planted; and the National Arboretum, Ottawa. Other possible walnut varieties include the Carpathian walnut, Juglans regia L., and the Japanese walnut, Juglans sieboldiana maxim. The former varieties produce prolific crops in the western and southern USA The latter is hardy in southern Ontario. In eastern Ontario it is growth as an ornamental. Horticultural varieties (8), however, have nut production possibilities in Eastern Ontario. 2. Fruit Walnut varieties have been propagated for their nut meats. Occasionally a tree appears with excellent nut producing qualities. Look for trees with: large size nuts; good nut meat yield, plump, well flavoured; thin, easily cracked shells; the two halves separate easily; consistent whitish nut meat; light coloured skins, not dark skins. If one of these is found it should be carefully tended by removing undesirable competition, pruning, fertilizing and protecting. Scions should be collected and grafted to a sturdy walnut root stock. Groves using the grafted stock should be established. (i) Yields (12) (1) A mature walnut will yield from twenty five to fifty kilograms (fifty to one hundred pounds of nuts. About three quarters of a square meter of trunk cross-section at one and a quarter meters above the ground per hectare (about a half square yard per acre at breast height) of land produces the best nut crops. (ii) Uses The fruit has many uses. The hulls yield a permanent yellow dye. The shells can be used as buttons, ornaments, mulch and fine abrasives. The meat has a strong distinctive flavour (18) for specialty baking and toppings, following recipes (17) for walnuts published in the Chapter's nut cookbook. De-husk nuts immediately, and dry in a cool, well-ventilated area. Black walnuts can be de-husked several ways. One is to cut the husk into four wedges with a paring knife, and peel off the sections by hand. Use kitchen gloves to prevent the copious black stain from tanning your skin. A second method is to roll the nuts underfoot on a hard surface, then wash them down. A third method, suitable for large volumes, is recommended by Fred von Althen. Put a quantity of nuts into a cement mixer along with a few fist sized rounded stones and some water. Let the mixer run about a half hour. Drain, recover the nuts and dry them. Doubtless, there are other methods. (iii) Crackability Walnuts are difficult to crack. Use a hammer on the nut's suture line, tapping lightly. Use an inertial-type cracker . Place the nut end-on in the cracker so the striker hits the nut on its pointed end. In any case, the long term objective is to grow varieties that crack easily. 3. Wood The wood is prized for fine furniture and fittings either as dimension lumber or veneer. About one and three quarter square meters of trunk cross section per hectare (about five square feet per acre) yields the best timber volume. The wood is heavy, hard, strong, straight-grained, diffuse, porous, and dark brown with paler sapwood. Burls and roots are very valuable. 4. The Growing site The tree prefers a deep (about one and a half meters or five feet), well-drained, non-acidic loam. A slope is preferable to allow cold air to drain away. Protect from north winds with a windbreak. As with any orchard, access must be available for year-round silviculture. 5. Site Preparation (5) (9) Complete site preparation is preferable for successful establishment and rapid growth. At the Baxter Nut Grove, each individual tree site was treated with Roundup¨ specifically to kill the quack grass prior to planting. Walnuts may be inter-cropped if wide spacing is used. Be sure the tree has room to expand its feeder roots without competition from undesirable weeds. 6. The Planting Stock (8) Selected stock should be planted. Seedlings of known origin are desirable but do not produce completely true to form. Grafted stock from at least two varieties is the most desirable material. Walnuts generally bear every two years so alternate year cultivars are required. Wind pollination requires male and female flowers to be in synchronization for successful fertilization. Commercial nurseries may be able to supply tested, hardy horticultural varieties. 7. Planting the Stock Plant at pre-determined spacing. At the Baxter Nut Grove, three specimens were planted in a triangle in each planting. This strategy significantly improves the chances that at least one tree will survive (the others, if necessary, would eventually be removed leaving the best tree growing in that spot). Make a detailed management plan based on your objectives and use it as a guide. Preferably, walnuts should be planted in situ, as seed, rather than transplanted. If transplanting is necessary, seedlings two or three feet in height succeed best. (ii) Cut off large seedlings, leaving a two to three inch stem and a shortened tap root pruned free of defects. (ii) For an inter-cropping and nut production site, prepare the site fully the year before. Plant the trees at either fifteen meter (about forty foot) spacing or three meter (about ten foot) spacing in the inter-crop rows. Cull out (thin) undesirable trees to attain the fifteen by fifteen meter (about forty by forty foot) spacing. Choose an intercrop of hay, oats, etc. and plant it between the rows leaving at least a two meter (about seven foot) strip for the trees. Walnut in mixture with red or white pine, planted as a nurse crop to enable the walnuts to get started, have proved successful in eastern Ontario.(ii) Walnut roots produce a natural substance called juglone which is toxic to some plants, especially pines. Consequently, when the walnuts have reached a robust size, the juglone eliminates the pines from the plantation, releasing the walnuts. Walnuts may also be mixed with other tolerant hardwood species at closer spacing. Plant early in the spring by hand. 8. Tending (5) (9) Keep the root zone free of weeds. Mulch the trees with sawdust or wood chips. At the Baxter Nut Grove, the trees are mulched with wood chips to a depth of about five centimeters (two inches). The mulch is replenished as it decomposes. Weeds that come through the mulch can be eliminated with Roundup. Site preparation should have eliminated the original actively growing weeds. Simazine applied early in the spring at from four to seven kilograms of active ingredient per hectare should then control most germinating annual weeds. A spot touch-up with Roundup¨ may be necessary for tough plants like quack grass. Also, do not use a metal pipe as a tree stake because it will conduct frost to the root system. (iii) 9. Pruning Correctively prune each tree over the years to form a single clean stem at least three meters (about nine feet) high for veneer logs or about six meters (about seventeen feet) high for timber. This will ensure a sound, knot-free log. Regular orchard pruning techniques, producing a full sound crown, also should be used. 10. Fertilization Walnuts require a high level of fertility. Annual soil tests will indicate deficiencies in nitrogen, phosphates, or potassium and trace elements like zinc, copper, iron or boron. Fertilize early in the spring. Do not encourage excessive shoot growth into the fall frost period by fertilizing after July 15th. 11. Special Propagation Techniques for Black Walnut Walnut may be propagated successfully vegetatively. Grafting, budding or root layering are all possible. When grafting be sure the scion base can drain off accumulated sap. Leave a small unwaxed hole at the base. To ensure a good veneer log, set scions on the root stock less than one and one half inches above the ground. Use one or two year old seedlings as root stocks. If a tree performs poorly as to form, cut it off at ground level in the fall and it will send up a strong sucker the following spring. Cut off any competing suckers.(ii) A homemade stratification box was constructed by Bob Scally and works well. Bob describes mixed plantings, transplanting and protection from rodents. (iv) Alec Jones gives useful tips on propagation in the Nuttery newsletter, vol. 7, no. 4. Fil Park describes underplanting a hardwood woodlot on an island in Big Rideau Lake, also in the Nuttery, Vol. 7, no. 4. Irene Woolford has started a black walnut/white pine mixture in Oak Valley on the South Nation River (South Nation Conservation Authority) (vii) as the second Chapter nut plantation project after the "Baxter Nut Grove" near Kemptville.