Trees are planted to give shade, to improve landscapes, and sometimes to produce food for man or wildlife. Nut trees provide all of these benefits. Wherever trees can be grown in the United States there are one or more kinds of nut trees suited for the climate.

Black walnut, pecan, and hickory can reach heights beyond 90 feet when mature. Other nut trees are low and spreading, like Chinese chestnut, butternut, Japanese walnut and heartnut. In outline they may resemble old fashioned apple trees. Almond trees are even smaller, while filberts and chinkapin chestnuts are little more than shrubs. If an evergreen is needed, large seeded nut pines are suitable.

The pecan is the most popular nut tree native to the United States. It is a species of hickory and in the same plant family as walnuts. The pecan grows throughout the southern United States from the Carolinas to Arizona and north, along river bottom land, as far as Iowa in the Midwest.

Pecan trees prefer a rich, deep, well-drained soil, and long, warm growing seasons. In the South the frost-free period extends from 190 to 220 days, but it may be as short as 150 days in the Midwest. Although trees will survive in much of the Northwest and Northeast, the cooler summers don't allow development of full kernels.

Numerous varieties have been selected for their fine nuts and other desirable characteristics. Early maturing selections are required for the Midwest. In the high rainfall area of the Southeast, disease-resistant varieties that need less spraying are preferable.

Besides pecan trees there are several other native hickories. Two, shellbark and shagbark, are notable for their sweet tasting nuts. They are hardier than pecans. Though shellbark and shagbark are not grown in commercial orchards, amateur nut growers propagate and grow several selections having large kernels that separate readily from the shell when cracked. Shellbark hickory does best on lowland and river bottom soil. Shagbark is common on thinner, more acid, upland soils.

Eastern black walnut is our most valuable native hardwood, and the nuts are harvested in huge quantities each year. The nuts' tangy flavor isn't lost even in baking.

Black walnuts, native to the eastern United States, are grown from Nebraska and Texas to southern Vermont and South Carolina. They do best on limestone-derived soils.

Persian (English) walnut is an introduced species. Like almond, filbert, and pistachio, it is adapted to the West Coast. These nut trees all originated in arid, mild climates of Europe, Asia, and the Middle East. The climate of parts of California, Oregon, and Washington is similar to that of their native habitat. Hardy members of the species are grown extensively in home and farm yards in the Midwest and East. They are often referred to as the "Carpathian" strain because many originated in the colder Carpathian mountains of Europe.

Butternut is an extremely hardy, native walnut valued for its nuts in the colder areas of our north central and northeastern states. Other species of walnut, such as the Japanese walnut and heartnut and their hybrids, are locally important.

Pecan Varieties
Variety	State of origin	Pollination type*	Relative production	Kernel quality	Disease resistance
Southeast
Chickasaw	Tex.	II	exellent	fair	good
Desirable	Fla.	I	good	good	fair
Elliott	Fla.	II	good	fair	good
Farley	-	I	fair	exellent	fair
Kernodle	Fla.	II	fair	good	fair
Mahan	Miss.	II	fair	poor	poor
Schley	Miss.	II	good	exellent	poor
Stuart	Miss.	II	good	good	good
Southwest
Ideal	-	II	good	good	poor
San Saba Imp.	Tex.	I	good	good	poor
Sioux	Tex.	II	good	exellent	poor
Western	Tex.	I	exellent	good	poor
Wichita	Tex.	II	exellent	exellent	poor
Midwest
			Kernel quality	Remarks
Colby	Ill.	II	poor	Retains foilage late in fall
Fritz	Ill.	II	-	Hardy tree for extreme north
Greenriver	Ky.	II	good	Susceptible to spring frost
Major	Ky.	I	good	Good producer; susceptible to aphids
Perque	Mo.	I	good	Susceptible to aphids, squirrels and birds
* I. Pollen shed before females are receptive. II. Pollen shed after females are receptive. Interplant at least one tree from each group for best pollination.

Commercial production of filbert (hazelnut) is limited largely to Oregon's Willamette Valley where the European filbert variety Barcelona is the principal selection grown. The American filbert, hybrids with the European filbert, as well as some European varieties are grown in the eastern United States. Eastern filbert blight and cold winters restrict their wider use.

Almonds and pistachio are grown in the Sacramento and San Joaquin Valleys of California and to a limited degree in other southwestern States. Spring frosts, high humidity, and rainfall limit their success elsewhere.

American chestnut was destroyed by an introduced bark parasite in the early half of this century. Blight-resistant Oriental chestnut trees, notably the Chinese chestnut, are widely grown for their nuts. They are hardy and thrive wherever peach trees can be grown.

Chinkapin chestnuts, native to the Southeast, are small trees or shrubs that bear small, tasty nuts. The Chinkapin nut size makes them especially suitable producers of wildlife food.

Macadamia is a tropical nut tree of Australia and now an important crop in Hawaii. The tree has met with some success in warmer areas of California and in Florida.

Other trees such as oak, beech, ginkgo and pine, often not thought of as nut trees, can be grown for their nut fruit. Among the nut pines, pinyon pine is native to the arid Southwest, Korean pine is hardy in the Northeast, and Italian stone pine is hardy in the Deep South.

Flowering

Pecans, hickories, walnuts, filberts, and chestnuts have both male and female parts on the same shoot, but in separate flowers. In pistachio the male and female flowers are borne on separate trees. Flowers of these species are not showy and are largely wind-pollinated, except for chestnut which is both wind- and insect-pollinated.

Walnuts and hickories, including pecans, shed pollen about a month after the buds break in spring, while filberts flower during the winter or early spring before vegetative growth begins. Chestnuts, by contrast, flower later, about two months after shoot growth begins in spring.

Many pecan, walnut, filbert, and chestnut varieties or seedlings are unfruitful unless they receive pollen from another tree of the same species. Failure of self-pollination may be due to a difference in time of pollen shedding and female receptivity on the same tree, or a pollen incompatibility. To ensure cross pollination, two or more varieties need to be present in a planting.

Almond—related to peach, plum, and other stone fruits—and macadamia have colorful flowers and are pollinated by honey bees, which are usually prevalent in residential areas. Macadamia is self-fertile. Almond flowers are self-incompatible, so two or more compatible varieties must be selected for a planting to insure pollination.

Numerous superior pecan trees have been selected from native groves. Recently, outstanding varieties have been developed from the breeding program sponsored by the U.S. Department of Agriculture at Brownwood, Tex.

Newer selections of Persian walnut, like pecan, are considerably improved over older varieties. Many of the new Persian walnut varieties bear on lateral branches or spur shoots and are capable of producing more nuts. They have also been selected for hot or for cool climates. Characteristics of several of the older and newer varieties grown on the West Coast are given in the second table.

Persian Walnut Varieties for West Coast
Old varieties	Danger of spring frost damage	Relative production	Kernel quality	best adapted to
Eureka	moderate	good	exellent	cool
Franquette	none	poor	good	cool
Hartley	slight	good	good	hot
Payne	great	exellent	exellent	cool
New varieties
Amigo*	slight	good	fair	cool
Chico*	moderate	good	good	hot
Gustine	moderate	exellent	exellent	hot
Lompoc	moderate	good	good	cool
Midland	slight	good	good	cool
Pioneer	slight	good	fair	hot
Pedro*	slight to none	good	good	cool
Serr	moderate	good	exellent	hot
Tehema	slight to none	exellent	good	hot
Viva	moderate	exellent	exellent	hot
* Good pollen producers for cross pollination with other varieties.

Many varieties of Carpathian walnut are adapted to the Midwest and East. These include Colby, Hansen, Lake and Metcalfe. Unfortunately, such selections are not readily available from nurseries.

The most widely planted almond variety is Nonpareil. Mission, Ne Plus Ultra, and Peerless are often used to pollinate it. However, the newer varieties—Davey, Karpareil, Merced, and Thompson—are also good pollinators for Nonpareil, and produce better quality kernels.

Barcelona is relatively resistant to most insects and diseases but the nuts are poorly filled. Several new hybrids yield more kernel per nut but produce smaller crops. In Washington, Noosack is commonly grown with Alpha and DeChilly as pollinators. Royal is adapted to colder areas along with Gem or Hall's Giant.

Availability of varieties of walnuts, butternuts, heartnuts, chestnut, filberts for the East, and shellbark and shagbark hickories is like that for Carpathian walnuts. Outstanding trees selected for vigor, production, nut size, and good cracking have been named and propagated, largely by amateur nut growers, but few nurseries list them.

Location, Spacing

Pecans and the large walnut trees should be spaced at least 40 to 50 feet from buildings, trees, and other obstacles if they are to remain a long time. Trees on poor soils with inadequate water will reach only half to three-quarters the size of those growing under good conditions. In areas of late spring frosts, plant on the north side of buildings to delay bud break in spring. Or plant on the upper portion of slopes to avoid frost pockets.

Smaller filbert and almond trees may be spaced about 25 feet apart. Almond is drought-hardy and tolerates poor soil, but it must not be exposed to late spring frosts. Filberts have shallow roots and can be grown on relatively shallow soils.

Chinese chestnut trees grow to about 40 feet and should be planted about 40 feet apart. They prefer an acid soil, pH 5.5, in contrast to the various walnuts which generally perform better on less acid soil, pH 6.5.

All nut trees should be planted when dormant after leaf fall and before leafing-out in spring. If the roots of a dug tree are allowed to dry, the tree will probably die. Buy young trees from reputable nurseries.

A narrow, deep hole is required to accommodate the pecan's tap root; roots of other nut trees spread out more as a rule. The hole should be large enough so tree roots are not twisted and folded back.

Once in the hole with soil filled back in, the tree should be gently lifted a little so the roots point down. Final depth of the tree in the soil should be the same as in its former location, and can be determined by the different bark color at the old soil line. Apply water to settle soil around the roots and prevent the tree from drying out.

For the first year after planting, the goal is to keep the trees alive. Ample soil moisture is the most critical factor. An inch of water per week by rain or irrigation is adequate. Excessive daily watering may waterlog the soil and kill a tree as readily as lack of water.

Maintenance of an area around the tree base free of weeds and sod will maximize tree growth. A mulch or herbicides will assist in controlling weeds and conserving moisture.

Pruning can begin the winter after the first summer of growth. Large trees like pecan and Persian walnut should be trained to a modified central leader (main trunk) rather than an open vase. A tree of this type has 5 or 6 main branches radiating from the trunk, beginning at a height of 5 feet to prevent limbs sagging to the ground. The central leader system gives greater strength and results in less limb breakage. After the first 5 years, when the tree is shaped, little pruning need be done except to thin crowded or dead branches.

As trees mature, prune out crowded branches. But don't cut back the terminal portion of pecan twigs, because these bear the fruit. The terminals can be pruned back on most walnuts because they bear on lateral twigs. If the variety does not fruit well on lateral branches, cut the main branches about a quarter of the way back.

On older pecan and walnut trees where seasonal growth is only a few inches, many small cuts may be necessary to thin fruiting wood and open up crowded areas of the tree. This type of pruning will stimulate new growth and rejuvenate the fruiting wood.

Filberts commonly form suckers at the base and grow in bush form. In the Northwest, suckers are removed to maintain single-stemmed trees. In the East, filberts grow best as multi-stemmed shrubs, but thin suckers constantly to maintain tree vigor.

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 arid 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 shellbark 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 kernal 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 dieback, 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.