Fertilizer

Shortly after planting, a handful of 10-10-10 can be broadcast around the tree, but not in the tree hole. Excessive fertilizer or a heavy narrow band can result in damage or even death of young trees. The second year and thereafter, add 1 to 4 pounds of 10-10-10 per inch of trunk diameter during winter in the South or early spring in the North. Nitrogen is the most commonly lacking nutrient; deficient trees have weak growth, pale green foliage, and small leaves. In Western areas, walnuts can suffer the effects of many nutrient deficiencies and even excessive toxic amounts of some elements.

Potassium deficiency is common where topsoil has been removed by land leveling, construction, or where the soil is extremely sandy as in and western areas and where excessive nitrogen has been applied in the southern United States. Boron, manganese, iron, copper, and magnesium can also be deficient.

Many States have Cooperative Extension Service laboratories, which will analyze soil and plant tissue samples. Consult local agricultural authorities for advice on taking leaf or soil samples and interpreting results as regards fertilizer needs.

Production of good nuts often depends on pest control. An itemized list of potential spoilers would be long but for each tree species there are only a few notable insects or diseases expected. Consult local agricultural authorities on identifying pests, control measures, and current pesticides registered for use.

The most common disease of pecan trees in humid areas is scab, which affects leaves and nut shucks and can ruin the crop. Crown gall, a bacterial disease which forms tumors at the base of the tree trunk, is also prevalent in some locations. Aphids, mites, spittlebug, and leaf casebearer all feed on foliage. Shuckworm and pecan weevil, as well as spittlebug, are the insects most damaging to nuts. Most pecan varieties have little resistance to scab and no resistance to the above insects. Shagbark and shell-bark hickory are attacked by the same pests as pecan.

One of the most serious pests of Persian walnut in the West is the navel orange worm. The larvae eat the kernel while the nuts are still on the tree. Harvest nuts early and clean up nut husks, leaves, and dead limbs to reduce damage from this pest. The maggot of the husk fly, and codling moth larvae, can cause early season destruction of the immature kernel or stain the kernel in late season. The walnut weevil or butternut curculio may also attack the nut, but of greatest consequence is larval injury to stems and branches.

Walnut blight, caused by bacteria, is found on all walnut species, but the Persian walnut seems the most susceptible. The disease rarely kills a tree but infects trunk, limbs, shoots, and leaves, spreading to the nuts which are destroyed. The bacteria overwinters in dead twigs infected the year before, so complete sanitation practices will help eliminate the pest.

Walnut anthracnose or leaf blotch is caused by another bacterium. Symptoms include defoliated trees and unfilled, deformed nuts. Fungicidal sprays are the usual control.

Another serious problem with all walnuts and some pecan varieties is bunch disease. Symptoms include die-back, stunting, and brooming of growth. The causal agent is a mycoplasm. Control measures are unknown.

Brown rot and shot hole fungus are two serious diseases of almond fruit. Bacterial canker is also prevalent during rainy spring weather and affects blossoms and young shoots. These diseases can be controlled with dormant sprays and fungicide applications in early spring. Insects such as brown almond mite, peach twig borer, and plant bugs can be controlled with insecticides. Red spider mite, as with other nut trees, may occur in late summer, especially under dusty, dry conditions. It can be controlled by spraying.

Insects and diseases have not been a serious problem with filberts in the Northwest. But in the East, eastern filbert blight and filbert bud mite have limited the successful growing of filbert as yard trees. Effective control measures have not yet been developed.

Chestnut blight fungus, the disease that destroyed the American chestnut, may also attack the more resistant Chinese chestnut trees. Pruning weak, shaded branches, as well as suckers, and keeping trees in vigorous condition helps control blight damage on resistant trees. Chestnut weevils (two species of curculio) infect ripening fruit, and feeding larvae cause great damage to nuts. These weevils can be controlled with sprays.

In areas where particular pests cause serious damage, yearly preventive sprays are warranted. Other pests may be controlled by careful observation, taking control measures when you see the pest or damage. Spraying for one pest often may limit other similar pests present at the same time.

Harvest, Storage

Ripening of nuts occurs from August to November, depending on the species and variety. With the exception of chestnut, most nuts have a high oil content and long shelf life. However, harvest nuts immediately after they fall from the tree, especially where there is rodent predation, rainfall, high humidity, or hot weather. Ripe nuts remaining in trees can be knocked off with poles.

Husks of pecan, shagbark and shellbark hickory, chestnut, and Persian walnut open and fall off when the nut is ripe. The husks of black and other walnuts have to be removed. All nuts should be air-dried before storage. Nuts, especially pecans, keep longer if left in the shell and refrigerated at 35 F. Shelled nuts keep well frozen.

Chestnuts, with their low oil and high carbohydrate content, have special needs and should be refrigerated at 35 to 40 under high humidity shortly after harvest. One method is to take the freshly harvested nuts, that have a high water content to begin with, mix them with slightly damp or nearly dry peat moss, and refrigerate in closed plastic bags.

Because so many selected varieties of nut trees are not readily available commercially, amateur growers may decide to do their own propagating. Trees can be grown from seed, but seedlings seldom produce as good nuts as named varieties. However, seedlings can be converted to a named selection by grafting or budding a short stick (scion) or bud of a selection to them.

Techniques used to propagate selected varieties are explained in numerous pamphlets and books. The rootstock and scion are usually of the same or closely related species.

Most temperate climate nuts germinate best if they receive a cold treatment. This may be supplied by refrigeration at 40 F, or simply by sowing the nuts in the fall and letting mother nature furnish the moist cold treatment during winter. Where temperatures well below freezing are expected, a straw or similar type mulch should cover nuts in winter. Protection from rodents, such as wire screening, may also be needed.

How often when the suggestion is made to plant a nut or fruit tree does the answer come back, "Why bother? By the time the tree bears, I'll be gone." Such a response shows an unfortunate short-sightedness and lack of concern for those who come after us. If Johnnie Appleseed or so many others had thought this way, the world would be the poorer for it. The tree planter leaves a valuable legacy behind him, not only in a harvest of wood but in valuable food sources of man and wildlife and a better place to live.