[Edited_by_A._Ciancio,_C.N.R.,_Bari,_Italy_and_K.(Bookos.org)

IPM IN PECAN PRODUCTION
135
Pecan nut production in orchards is a viable agribusiness especially in the
southern US. Pecan trees will produce a crop of nuts with little or no management.
In fact, a large portion of the USA crop is produced on native stands with very low
inputs. These stands have much lower average production per hectare than seedling
or improved pecan orchards and inputs have to be held to a low cost. Pecans initially
were harvested by hand. Harvesters would climb each tree and shake individual
limbs or knock nuts off the limbs with bamboo poles, while coworkers would pick
them up off the ground. Mechanical trunk and limb shakers are currently used to
dislodge the nuts out of the tree and onto the orchard floor. Hand picking off the
ground has been replaced by a mechanical process where the fallen limbs are raked
over to the edge of the orchard, the nuts and leaves are swept into rows, the leaves
are blown off the row and the nuts are picked up from the row by a mechanical
harvester. Nuts are sorted and cleaned in the orchard and then transported to the
shelling plant where they are sanitized, dried and then typically cracked, shelled and
frozen. Harvesting is most efficient when the orchard floor is dry, level, and cleared
of weeds and debris. Efficient harvesting is needed to prevent depredation of the
nuts by birds and mammals and environmental degradation of the nuts.
Native stands of pecans provided nuts as a source of food for indigenous
people of America and early settlers propagated seedling trees through the southern
US. Many of the native groves were developed, by European settlers, as a newworld
adaptation (Brison, 1974) of the European silvopastoral systems that provided
many of the staples of the rural community – milk, meat, hides, wood, and nuts
(Auda, 1999). Grafting techniques were developed in the mid-1800s and improved
cultivars with desirable characteristics were selected from native and seedling trees
or from controlled crosses from amateur or professional plant breeders. Improved
cultivars have been propagated across the southeastern US, and in New Mexico,
Arizona and California to the extent that the production of nuts from improved
cultivars often exceeds the production of native and seedling orchards (Worley,
2002).
Nut production in the US is currently based on ~10 million managed trees
planted on ~200,000 ha on 20,000 farms in 24 states producing roughly 146,000
metric tons of in-shell nuts each year. Most orchards are small in area. Sixty-two
percent of the farms have less than 6 ha, 32% have 6–40 ha, 5.4% of the farms have
40–200 ha and 0.7% of the farms have more than 200 ha. Orchards with less than 40
ha comprise 56% of the production area in the USA (Wood, 2003). Improved
cultivars have contributed to increases in pecan production. Today’s new cultivars,
however, are only 2–3 generations removed from wild trees (Sparks, 1992) and
pesticides – esp. fungicides – have had a more significant impact on increasing USA
pecan production than cultivars. In fact, native groves produce approximately 30%
of the US nut crop and seedling and improved cultivars planted in commercial
orchards produce the remaining crop (Pollack, 2001). Pecan trees have a producing
lifespan of at least 80 years and grow to over 30.5 m in height. Production is
irregular from season to season. USA production per season ranges from 45.4
to 163.2 million kg of nuts in the shell. The kernel typically comprises ~50%
of the mass of the nut in the shell. Growers typically sell pecans in the shell for
$1.50–5.00/kg to processors and many growers process, package, and market their