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Cultivation

Pecans are one of the most recently domesticated of the major crops. Although wild pecans were well known among native and colonial Americans as a delicacy, the commercial growth of pecans in the United States did not begin until the 1880s. As of 2014, the United States produced an annual crop of 119.8 million kilograms (264.2 million pounds), with 75% of the total crop produced in Georgia, New Mexico and Texas. They can be grown from USDA hardiness zones approximately 5 to 9, and grow best where summers are long, hot and humid. The nut harvest for growers is typically around mid-October.

Outside the United States, Mexico produces nearly half of the world's total, similar in volume to the United States, together accounting for 93% of global production. Pecan trees require large quantities of water during the growingseason, and most orchards in the region use flood irrigation to optimize consumptive water use and production of mature pecans. 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 zone 9 to zone 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.