The almond is not a true nut but belongs to the Rose family. All varieties produce better if pollen from another tree is available. Peaches and almonds, being of the same family, will pollinate each other.
Butternut has an inhibitory effect on plants within its immediate vicinity, but to a lesser degree than the black walnut. (See Walnut entries.)
Butternuts
This native of Brazil has become naturalized in many tropical countries and will grow on sandy soils in Florida. Cross-pollination is not necessary.
The chestnut blight has just about wiped out the native American species. However, much work has been done to develop disease-resistant varieties, and a revival of this tree is in progress.
Plant two or more varieties for cross-pollination.
In ancient times many believed that a forked hazel twig had supernatural powers. Such twigs are mentioned in the Bible, while the Romans also describe the magical quality of the branches and told of hazel divining rods being used to find water and precious minerals underground.
Hazelnuts
Hazels furnish valuable cover and food for wildlife. Homeowners also plant them as ornamentals or to shelter other plants. In some forests hazels form such dense thickets that tree seedlings cannot grow and heavy machinery is needed to uproot them so more valuable timber can be planted.
Hazel trees and bushes are beneficial in pastures and elsewhere against flies. Cows like to nibble on the leaves, which increase the butterfat in their milk, while the tannic acid also acts as a cleansing agent for their digestive systems.
It is recommended that two varieties be planted for cross-pollination and better crops.
The hickories, like the walnuts, have male and female flowers growing separately on the same shoot of the current season’s growth. Many varieties appear to be self-unfruitful, so it is good practice to plant several varieties together to ensure cross-pollination.
These trees in all their varieties give no evidence of crossincompatibility, and all will bear larger crops if two or more varieties are planted together.
Pecan trees like plenty of nitrogen. In the orchard, plant a winter and spring cover crop such as clover, which harbors nitrogen-fixing bacteria. For a lawn specimen, let a dense mat of grass grow near the trunk to conserve soil moisture and prevent sunscald of the roots. It is good to mulch with grass clippings, too.
Pecans
The casebearer and hickory shuckworm, the most serious pecan pests, are best foiled by releasing trichogramma wasps in the orchard. Do not store pecan meats near onions or oranges.
Grafted varieties of these self-fruitful trees usually produce each year, while wild trees generally produce well only in alternate years, some only every third year.
Black walnut trees are known to produce a substance called juglone, which is washed from the leaves to the soil, inhibiting the growth of many plants within the area where the trees grow. Cultivated plants not compatible with black walnuts are apples, alfalfa, potatoes, tomatoes, blackberries, azaleas, rhododendrons, and heathers. The butternut also seems to have this quality, but plants near it are less severely affected. (See also Sycamore in the Trees and Shrubs chapter.)
Walnuts
Toxicity is contained in the roots of black walnuts as well as in the leaves, and because of this many plants will not grow near the tree. But not all are discouraged. Right at the drip line of a black walnut I have a bed of rainbow-colored iris, interplanted with daylilies, grape hyacinths, and daffodils, none of which appear to be in the least affected.
Drawbacks aside, the black walnut is prized for its valuable wood and delicious nuts. In addition, the tree’s leaves scattered around the house or put in the dog kennel will repel fleas.
A Russian remedy to prevent sunburn is to rub freshly ground walnut leaves on the skin. The dark juice of walnut hulls applied to ringworm is said to heal the scalp. (See also Walnuts, English, below.)
Unless you live in a favorable climate, you will probably be more successful with a tree of the Carpathian type, which will do well farther north.
Walnuts are monoecious — that is, the male and female blossoms are separate on the same tree. They are self-fertile but produce better in plantings of several nearby.
English walnuts do not have the level of detrimental leaf and root excretions found in black walnuts, but their shade makes it difficult to grow some plants nearby. Many of the fruit mints, such as apple, orange, pineapple, and spearmint, will do well, however, as will angelica, sweet anise, and other herbs that like filtered sunlight.