Sapling and pole stages to maturity Growth and yield: The hickories as a group grow slowly in diameter, and shellbark hickory is no exception. Sapling size trees average per year in diameter growth, increasing to per year as poles and sawtimber. Second-growth trees show growth rates of per year. Shellbark hickory occasionally grows to a height of and a diameter of . Rooting habit: Shellbark hickory develops a large taproot that penetrates deeply into the soil. Lateral roots emerge at nearly right angles to the taproot, spreading horizontally through the soil. Major distinct lateral roots usually develop 12 inches or more below ground level and appear only after taproot is well formed. In Illinois, root growth was rapid in April, slowed during July and August, increased again in September, and ended in late November. Mycorrhizal associations are formed when trees are young. The only specific fungus identified from shellbark hickory roots is an ectotrophic mycorrhiza,
Laccaria ochropurpurea. Reaction to competition: Shellbark hickory is very shade-tolerant, exceeded only by
sugar maple (
Acer saccharum) and
beech (
Fagus grandifolia). It grows slowly under a dense canopy, however. In stands with only partial shade, it reproduces well. It is a very strong competitor in most of the species associations in which it is found. Under forest conditions, shellbark hickory often develops a clear bole for half its length and has a narrow, oblong crown. Open-grown trees have egg-shaped crowns. Heavy release sometimes results in epicormic branching. On mature trees, the bark peels away from the trunk in long, sometimes broad, strips. This gives the trees a "shaggy" appearance that is easily confused with that of the Shagbark hickory (
Carya ovata). That close similarity is the reason Shellbark hickories are frequently misidentified. A closer examination of other traits is usually needed to distinguish the two species. Damaging agents: Although numerous insects and diseases affect hickories, shellbark hickory has no enemies that seriously threaten its development or perpetuation as a species. Seed production can be reduced significantly, however, through attack by several insects. Two of the most important are the pecan weevil (
Curculio caryae) and the hickory shuckworm (
Laspeyresia caryana). The hickory bark beetle (
Scolytus quadrispinosus) feeds in the cambium and seriously weakens or even kills some trees. Adults of the hickory spiral borer (
Agrilus arcuatus torquatus) feed on leaves, but the larvae feed beneath the bark and can be very destructive to hickory seedlings. The flatheaded appletree borer (
Chrysobothris femorata) likewise is a foliage-feeder as an adult, but its larvae feed on the phloem and outer sapwood. The living-hickory borer (
Goes pulcher) feeds in the trunks and branches of trees. A twig girdler (
Oncideres cingulata) can seriously affect reproduction by killing back the tops of seedlings and sprouts. Both standing dead trees and freshly cut logs are highly susceptible to attacks by numerous species of wood borers. A large number of insect species feed on hickory foliage. None of them causes serious problems for shellbark hickory, although they may be responsible for some stem deformity and growth loss. Shellbark hickory is free of serious diseases, but it is a host species for a variety of fungi. More than 130 fungi have been identified from species of
Carya. These include leaf disease, stem canker, wood rot, and root rot-causing fungi. Specific information for shellbark hickory is not available. Shellbark hickory is susceptible to bole injury from fire, and fire injuries are often invaded by wood rot fungi. It is resistant to snow and ice damage, but is susceptible to frost damage. == Distribution and habitat ==