The pecan ( , , ; Carya illinoinensis) is a species of hickory native to the Southern United States and northern Mexico in the region of the Mississippi River.
Originally native to the south-central U.S., Weakley, A. S. (2015). Flora of the Southern and Mid-Atlantic States. Chapel Hill, NC, University of North Carolina Herbarium. the tree is cultivated for its seed primarily in the U.S. states of Georgia, New Mexico, and Texas, and in Mexico. The seed is an edible nut used as a snack and in various recipes, such as praline candy and pecan pie. The pecan is the state nut of Alabama, Arkansas, California, Texas, and Louisiana, and is also the state tree of Texas.
derives from an Algonquian word variously referring to pecans, walnuts, and hickory nuts. There are many pronunciations, some regional and others not.See "[[wikt:pecan#Pronunciation|Pecan]]" at [[wikt:Main Page|Wiktionary]]. There is little agreement in the United States regarding the "correct" pronunciation, even regionally.
In 1927, the National Pecan Growers Association acknowledged variant pronunciations while designating one as official and correct: "pronounced as though spelled pea-con ... those in the habit of using any other pronunciation therefore be requested henceforth to adopt exclusively the pronunciation above specified above and hereby adopted by the Association.""Proceedings, 27th National Convention, National Pecan Growers Association (27-29 September 1927, Shreveport, LA)," 153. Also cited in Chattanooga Daily Times, 30 September 1927, 7 ("Pecan Growers Vote Nut's Pronunciation").
A pecan, like the fruit of all other members of the hickory genus, is not truly a nut, but is technically a drupe, a fruit with a single Pyrena, surrounded by a husk. The husks are produced from the exocarp tissue of the flower, while the part known as the nut develops from the endocarp and contains the seed. The husk itself is aeneous, that is, brassy greenish-gold in color, oval to oblong in shape, long, and broad. The outer husk is thick, starts out green, and turns brown at maturity, at which time it splits off in four sections to release the thin-shelled seed.Collingwood, G. H., Brush, W. D., & Butches, D., eds. (1964). Knowing your trees. 2nd ed. American Forestry Association, Washington, DC.
C. illinoinensis is found in bottomlands, suburban woodlands, disturbed areas, and along forest edges; it commonly naturalizes near where cultivated trees are located. URL: http://herbarium.bio.fsu.edu. Last accessed: June 2018. Collectors: Loran C. Anderson, Bob Farley, and R.K. Godfrey. States and counties: Florida: Franklin, Leon, Gadsden, Jefferson, Jackson, Liberty, Washington, Holmes, and Madison. C. illinoinensis grows on soils that are not subject to frequent flooding, preferring moist, well-drained, rich soils.
The second major step in the development of pecan was a change from wind-dispersed fruits to animal dispersion. This dispersal strategy coincides with developing a husk around the fruit and a drastic change in the relative concentrations of fatty acids. The ratio of oleic to linoleic acids is inverted between wind- and animal-dispersed seeds. Further differentiation from other species of Juglandaceae occurred about 44 million years ago during the Eocene. The fruits of the pecan genus Carya differ from those of the walnut genus Juglans only in the formation of the husk of the fruit. The husks of walnuts develop from the bracts, bracteoles and sepals, or sepals only. The husks of pecans develop from the bracts and the bracteoles only.
The tree requires little pruning because it naturally forms a vase-shaped canopy; the only pruning necessary is to remove diseased, broken, or dead limbs.
In 2017, outside the U.S., Mexico produced nearly half of the world's total, similar in volume to that of the U.S., together accounting for 93% of global production. As of 2024, South Africa is the third largest producer, mostly exporting to China. Pecan trees require large quantities of water during the growing
/ref> Generally, two or more trees of different cultivars must be present to pollinate each other.
Choosing cultivars can be a complex practice, based on the Alternate Bearing Index (ABI) and their period of pollinating. Commercial growers are most concerned with the ABI, which describes a cultivar's likelihood to bear on alternating years (index of 1.0 signifies the highest likelihood of bearing little to nothing every other year). The period of pollination groups all cultivars into two families: those that shed pollen before they can receive pollen (protandrous) and those that shed pollen after becoming receptive to pollen (protogynous). State-level resources provide recommended varieties for specific regions.
Native pecans in Mexico are adapted from zones 9 to 11. Little or no breeding work has been done with these populations. A few selections from native stands have been made, such as Frutosa and Norteña, which are recommended for cultivation in Mexico. Improved varieties recommended for cultivation in Mexico are USDA-developed cultivars. This represents a gap in breeding development given that native pecans can be cultivated at least down to the Yucatán peninsula while the USDA cultivars have chilling hour requirements greater than those occurring in much of the region. Some regions of the U.S. such as parts of Florida and Puerto Rico are zone 10 or higher, and these regions have limited options for pecan cultivation. 'Western' is the only commonly available variety that can make a crop in low-chill zones.
While selection work has been done since the late 19th century, most acreage of pecans grown today is of older cultivars, such as 'Stuart', 'Schley', 'Elliott', and 'Desirable', with known flaws, but also with known production potential. Cultivars such as Elliot Pecan are increasing in popularity due to resistance to pecan scab. The long cycle time for pecan trees plus financial considerations dictate that new varieties go through an extensive vetting process before being widely planted. Numerous varieties produce well in Texas, but fail in the Southeastern U.S. due to increased disease pressure. Selection programs are ongoing at the state level, with Alabama, Arkansas, Florida, Georgia, Kansas, Missouri, New Mexico, and others having trial plantings.
Varieties adapted from the southern tier of states north through some parts of Iowa and even into southern Canada are available from nurseries. Production potential drops significantly when planted further north than Tennessee. Most breeding efforts for northern-adapted varieties have not been on a large enough scale to significantly affect production. Varieties that are available and adapted (e.g., 'Major', 'Martzahn', 'Witte', 'Greenriver', 'Mullahy', and 'Posey') in Hardiness zone and farther north are almost entirely selections from wild stands. 'Kanza', a northern-adapted release from the USDA breeding program, is a grafted pecan having high productivity and quality, and cold tolerance.
Pecans are prone to infection by bacteria and fungi such as pecan scab, especially in humid conditions. Scab is the most destructive disease affecting pecan trees untreated with fungicides. Recommendations for preventive spray materials and schedules are available from state-level resources.
Various insects feed on the leaves, stems, and developing nuts. These include ambrosia beetles, twig girdlers, pecan nut casebearer, hickory shuckworm, phylloxera, curculio, weevils, and several aphid species.
In the Southeastern U.S., nickel deficiency in C. illinoinensis produces a disorder called "mouse-ear" in trees fertilized with urea.
Similarly, zinc deficiency causes rosetting of the leaves. This can be compensated for by spraying the foliage with zinc sulfate every 2-4 weeks in spring and early summer. Moore, L. M. (2006). Plant Guide: Pecan Carya illinoinensis. N.R.C.S. United States Department of Agriculture. Baton Rouge, LA. Various other disorders are documented, including canker disease and shuck decline complex.
Pecan wood is used in making furniture and wood flooring, as well as flavoring fuel for smoked meat, giving grilled foods a sweet and nutty flavor stronger than many fruit woods.
Pecans first became known to Europeans in the 16th century. The first Europeans to come into contact with pecans were Spanish explorers in what is now Louisiana, Texas, and Mexico.These Spanish explorers called the pecan, nuez de la arruga, which roughly translates to "wrinkle nut". Because of their familiarity with the genus Juglans, these early explorers referred to the nuts as nogales and nueces, the Spanish terms for "walnut trees" and "fruit of the walnut". They noted the particularly thin shell and acorn-like shape of the fruit, indicating they were referring to pecans. The Spaniards took the pecan into Europe, Asia, and Africa in the 16th century.
In 1792, William Bartram reported in his botanical book, Travels, a nut tree, Juglans exalata that some botanists today argue was the American pecan tree. Still, others argue hickory, Carya ovata. Pecan trees are native to the United States, and writing about the pecan tree goes back to the nation's founders. Thomas Jefferson planted pecan trees, C. illinoinensis (Illinois nuts), in his nut orchard at his home, Monticello, in Virginia. George Washington reported in his journal that Thomas Jefferson gave him "Illinois nuts", pecans, which Washington then grew at Mount Vernon, his Virginia home.
Commercial production of pecans was slow because trees were slow to mature and bear fruit. To speed nut production and retain the best tree characteristics, grafting from mature, productive trees was the apparent strategy. However, this proved technically challenging. The Centennial cultivar was the first to be successfully grafted. This was accomplished by an enslaved person called Antoine in 1846 or 1847, who was owned by Jacques Telesphore Roman of the Oak Alley Plantation near the Mississippi River. The Grafting were supplied by Dr. A. E. Colomb, who had unsuccessfully attempted to graft them.
Alabama named the pecan the official state nut in 1982. Arkansas adopted it as the official nut in 2009. California adopted it, along with the almond, pistachio, and walnut, as one of four state nuts in 2017. Louisiana, known for pralines, adopted the pecan as its official state nut in 2023. In 1988, Oklahoma enacted an official state meal which included pecan pie.
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