Economic botany

In addition to being grown for their nutritious and delicious nuts, hickories are also valued for the utility and beauty of their wood, for their ornamental value in the landscape, and for their quality as a fuel wood.

The wood of hickories is known for strength and shock resistance, making it excellent for tool handles. It is also used extensively for sports equipment such as golf clubs, baseball bats, the backs of longbows, and laminae in tennis racquets and skis (Makepeace and Walker, 1989). High quality hickory is used as a flooring material for gymnasiums, roller skate rinks, and ballrooms. Some wood is used in making furniture, in piano construction, for butcher's blocks, for wall paneling, and interior trim. Hickory wood is also used for dowels, ladder rungs, and pallets (Harrar, 1958). Harrar (1958) reported that quality hickory lumber is in short supply, with much of the standing timber being so defective that harvest was not economical.

Hickory is considered to be an excellent fuel wood because of its density. One pound of any hardwood species yields about the same amount of heat as a pound of any other species of hardwood (8,580 to 8,920 BTUs per pound). However, wood is sold by the cord, which is a volume measure. Hickory wood is very dense, weighing about 4600 lbs. per cord and producing about 25 million BTUs per cord when burned. Lighter wood such as elm may weigh only 3200 lbs. per cord and produce 18 million BTUs when burned (Michaelson, 1978). Hickory wood is consumed in the smoking of meats and cheeses, where it imparts a distinctive flavor.

Of the 13 species described above, only pecan, shagbark and shellbark, have received much horticultural attention. In addition to their intrinsic ecological value, the remaining species are potentially useful for wood production or as specimen plants in the landscape. As more information is gained concerning mechanisms of disease and insect resistance or other genetic adaptations, these species could contribute to the development of the closely related pecan.

Bringhurst (1983) outlined 4 steps usually followed in the development of improved fruit crops from wild species: 1) identification of superior phenotypes in natural populations; 2) propagation of the best selections in an agricultural setting; 3) development of cultural practices that enhance performance of selected cultivars; and 4) hybridization among the best selections followed by selection of superior offspring (which are used as parents for further crosses). Despite their long history of utilization, the hickories are still at an early stage of crop development. Many "superior phenotypes" have been found in native populations, with nut characteristics being the primary basis of evaluation. The characteristics and performance of these "cultivars" following asexual propagation has been the focus of much of the literature related to hickory management. Unfortunately, observations are often based on one stion of a cultivar, often with a rootstock of another species and growing on mediocre sites.

A significant stage in the horticultural development of pecan occurred when orchards were planted using selected seed. Seedlings were evaluated for horticultural traits, with cultivars such as 'Stuart', 'Schley', 'Success', 'Delmas', 'Alley', and 'Pabst' arising from "select seed orchards" in Jackson Co., Mississippi. 'Western', 'San Saba Improved', 'Sovereign' ('Texas Prolific'), 'Onliwon', and 'Squirrels Delight' originated from an orchard of 1000 trees grown from seed of the 'San Saba', a native selection made by E. E. Risien of San Saba Co., Texas. The James orchard at Mound, Louisiana, was planted from selected seed and produced 'Carman', 'James', and 'Moneymaker' while in Florida, 'Curtis', 'Hume', 'Kennedy', and 'Randall' arose from the seedling orchard of J. B. Curtis (Crane et al., 1937).

Pecan cultivars have traditionally been selected primarily on the basis of nut characteristics, with selections being asexually propagated on seedling rootstocks in orchard configurations where intensive management can be economically justified. The limitations to economically feasible orchard establishment in the hickories are the extremely long period of juvenility (> 10 years), low yields (22 to 45 kg/tree, once in 3 yr), and large tree size. These native trees are plagued by many co-evolved disease and insect pests (Harris et al., 1986), especially when grown in a "monoculture" having large numbers of a limited number of cultivars. Conventional systems of orchard production have emphasized chemical control of pests, which is both economically and environmentally expensive. As a result, the culture of hickories tends to be "unconventional", with most practitioners being motivated more by aesthetics than economics.

The value of hickory wood creates an economic incentive to harvest this slowly renewable forest resource. Wise management should integrate the needs of forestry with a long range program of selection for the improvement of the stand. The systematic maintenance, management, and development of this valuable natural resource deserves thoughtful attention.

Warren Chatwin , Research Geneticist
USDA-ARS Pecan Genetics
10200 FM 50
Somerville, TX 77879
fax: 979-272-1401
e-mail: warren.chatwin@usda.gov

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