With a common name like “pignut hickory,” this is a tree that grabs your attention. And rightly so. Though not well-known outside the eastern part of the US, it is a very attractive, slow-growing native tree. Read on for more information about this useful tree.
I. Appearance and Characteristics
Carya glabra, the pignut hickory, is a common, but not abundant species of hickory in the oak-hickory forest association in the Eastern United States and Canada. Other common names are pignut, sweet pignut, coast pignut hickory, smoothbark hickory, swamp hickory, and broom hickory.
Hickories are monoecious and flower in the spring (3). The staminate catkins of pignut hickory are 8 to 18 cm (3 to 7 in) long and develop from axils of leaves of the previous season or from inner scales of the terminal buds at the base of the current growth. The pistillate flowers appear in spikes about 6 mm (0.25 in) long on peduncles terminating in shoots of the current year. Flowers open from the middle of March in the southeast part (Florida) of the range to early June in Michigan. The catkins usually emerge before the pistillate flowers.
The fruit of hickory is pear shaped and enclosed in a thin husk developed from the floral involucre. The fruit ripens in September and October, and seeds are dispersed from September through December. Husks are green until maturity; they turn brown to brownish-black as they ripen. The husks become dry at maturity and split away from the nut into four valves along sutures. Husks of pignut hickory split only to the middle or slightly beyond and generally cling to the nut, which is unribbed, with a thick shell.
Pignut hickory begins to bear seed in quantity in 30 years, with optimum production between 75 and 200 years. The maximum age for seed production is about 300 years. Good seed crops occur every year or two with light crops in other years; frost can seriously hinder seed production.
Pignut hickory tends to develop a pronounced taproot with few laterals and is rated as windfirm. The taproot develops early, which may explain the slow growth of seedling shoots. Taproots may develop in compact and stony soils.
Pignut hickory is easily damaged by fire, which causes stem degradation or loss of volume, or both. Internal discolorations called mineral streak are common and are one major reason why so few standing hickories meet trade specifications. Streaks result from yellow-bellied sapsucker pecking, pin knots, wormholes, and mechanical injuries. Hickories strongly resist ice damage and seldom develop epicormic branches.
II. How to Grow and Care
Sunlight
Pignut hickory plants are adaptable to grow in partial shade to full sun. However, it grows the best with full sunlight which means at least 8 hours of sunshine should be received.
Temperature
Native to North US, China and the rest of Asia, pignut hickory grows in an annual temperature ranging between 4 to 18 ℃, with 27 ℃ in summer and -15 ℃ in winter. Extreme temperatures observed range from 46 ℃ to -40 ℃. Throughout the distribution of pignut hickory, the mean annual rainfall ranges from 64 to 127 cm. During its peak growing season, rainfall ranges between 51 to 102 cm. Although it seems pignut hickory loves moist, it is somehow drought-tolerant and cannot stand waterlogging.
Watering
Keep regularly watering the newly planted plants after your first watering while transplanting. Once established, pignut hickory is drought tolerant, however, it is necessary to provide them 2.5 cm of water per week under dry and high-temperature conditions.
Soil
Pignut hickory can grow on a variety of soil conditions including moist sandy, loamy and clay soils, from moderately acidic to alkaline. But they perform superbly in moist, rich, slightly acidic to neutral (pH 6.1-7.3), silty loam that is well-drained.
Fertilizing
While transplanting, an application of slow-release fertilizer is recommended to enhance root establishment and favor early growth. Fertilizer for the established plants may be calculated on the basis of their truck diameter, you should follow the guide or manual of your fertilizer. Only notice that when you measure the trunk diameter, measure at a height of 1.3 m. Spread fertilizers evenly under the canopy once or twice a year in early spring and/or fall.
Planting Instructions
You can start your pignut hickory planting with either seeds or saplings. However, as pignut hickory is a medium- to slow-growing tree, it is recommended to plant saplings bought from a nearby nursery or gardening store. The excellent growth of pignut hickory is observed on raised beds with adequate moisture. You can make raised beds that fit the size of the root ball of the saplings for transplanting.
Prepare beds by digging deep earth up, loosening and mixing with the garden soil at a sunny location. Multiple trees should be spaced 6 to 7 m between the rows if grown in the orchards or as open field cultivation. What you should know is, none of Carya species are suitable for containers due to their deep, straight root system. You can only grow pignut hickory in your garden or orchard.
Pruning
Generally, pruning is not a necessity of pignut hickory but light pruning throughout the year can improve the light reception of inner foliage. Trimming is favored for the newly grown plants as well, which promotes growth. Don’t mess the main truck, just remove weak, broken and dead twigs on the secondary branches when noticed.
Propagation
Pignut hickory can grow on a variety of soil conditions including moist sandy, loamy and clay soils, from moderately acidic to alkaline. But they perform superbly in moist, rich, slightly acidic to neutral (pH 6.1-7.3), silty loam that is well-drained.
Pests and Diseases
The most common disease of pignut hickory from Pennsylvania southward is a trunk rot caused by Poria spiculosa. Cankers vary in size and appearance depending on their age. A common form develops around a branch wound and resembles a swollen, nearly healed wound. On large trees these may become prominent burl-like bodies having several vertical or irregular folds in the callus covering. A single trunk canker near the base is a sign that the butt log is badly infected, and multiple cankers are evidence that the entire tree may be a cull.
Major leaf diseases are anthracnose (Gnomonia caryae) and mildew (Microstroma juglandis). The former causes brown spots with definite margins on the undersides of the leaf. These may coalesce and cause widespread blotching. Mildew invades the leaves and twigs and may form witches’ brooms by stimulating bud formation. Although locally prevalent, mildew offers no problem in the management of hickory.
The stem canker (Nectria galligena) produces depressed areas with concentric bark rings that develop on the trunk and branches. Affected trees are sometimes eliminated through breakage or competition and sometimes live to reach merchantable size with a cull section at the canker. No special control measures are required, but cankered trees should be harvested in stand improvement operations.
A gall-forming fungus species of Phomopsis can produce warty excrescences ranging from small twig galls to very large trunk burls on northern hickories and oaks. Little information is available on root diseases of hickory.
More than 100 insects have been reported to infest hickory trees and wood products, but only a few cause death or severe damage. The hickory bark beetle (Scolytus quadrispinosus) is the most important insect enemy of hickory, and also one of the most important insect pests of hardwoods in the Eastern United States. During drought periods in the Southeast, outbreaks often develop and large tracts of timber are killed. At other times, damage may be confined to the killing of a single tree or to portions of the tops of trees. The foliage of heavily infested trees turns red within a few weeks after attack, and the trees soon die. There is one generation per year in northern areas and normally two broods per year in the South. Control consists of felling infested trees and destroying the bark during winter months or storing infested logs in ponds.
Logs and dying trees of several hardwood species including pignut hickory are attacked by the ambrosia beetle (Platypus quadridentatus) throughout the South and north to West Virginia and North Carolina. The false powderpost beetle (Xylobiops basilaris) attacks recently felled or dying trees, logs, or limbs with bark in the Eastern and Southern States. Hickory, persimmon (Diospyros virginiana), and pecan (C. illinoinensis) are most frequently infested, but other hardwoods also are attacked. Healthy trees growing in proximity to heavily infested trees are occasionally attacked but almost always without success.
Hickory is one of several host species of the twig girdler (Oncideres cingulata). Infested trees and seedlings are not only damaged severely but become ragged and unattractive. A few of the more common species of gall-producing insects attacking hickory are Phylloxera caryaecaulis, Caryomyia holotricha, C. sanguinolenta, and C. tubicola.
III. Uses and Benefits
- Ornamental uses
Colorful autumn foliage and interesting spring blooms make pignut hickory an especially showy tree. You can grow it as a large shade tree or smaller ornamental tree in wild or meadow gardens. Its flowers and fruits attract butterflies and birds to its branches, so it would also make a great addition to wildlife or pollinator gardens.
- Other uses
Hickories provide food to many kinds of wildlife. The nuts are relished by several species of squirrel and represent an estimated 10 to 25 percent of their diet. Hogs were observed consuming the nuts in colonial America, lending the species its common name. Nuts and flowers are eaten by the wild turkey and several species of songbirds. Nuts and bark are eaten by black bears, foxes, rabbits, and raccoons. Small mammals eat the nuts and leaves; 5 to 10 percent of the diet of eastern chipmunks is hickory nuts. White-tailed deer occasionally browse hickory leaves, twigs, and nuts.
The kernel of hickory seeds is exceptionally high in crude fat, up to 70 to 80 percent in some species. Crude protein, phosphorus, and calcium contents are generally moderate to low. Crude fiber is very low.
Pignut hickory makes up a small percentage of the biomass in low-quality upland hardwood stands that are prime candidates for clear cutting for chips or fuelwood as the first step toward rehabilitation to more productive stands. Hickory has a relatively high heating value and is used extensively as a home heating fuel.
Pignut hickory is an important shade tree in wooded suburban areas over most of the range but is seldom planted as an ornamental tree because of its size and difficulty of transplanting, although it has spectacular orangey-red fall colors.
IV. Harvesting and Storage
Notice that only pignut hickory trees older than 10 years start producing nuts. Harvest in fall when the brown, readily ripe nuts drop down on the ground. If the ripe nuts still stay on the tree, a gentle shake can promote free falls onto the ground. Pick the nuts from the ground before rodents and birds, remove the remaining husks and store the nuts with the outer shell where cool and dry if you are not eating them immediately. You can also crack the outer shell and store the meat of the nut by refrigerating or freezing.
Find Where to Buy the Best Pignut Hickory (Carya glabra)
[content-egg-block template=offers_logo_shipping cols_order=3,2,1,5,4 hide=badge visible=number border_color=info limit=8]