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in Tucson, Phoenix,
Arizona and California

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Growing Pecan: Carya illinoinensis

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Overview

A member of the Walnut family (Juglandaceae), the Hickory genus (Carya) has 27 species of deciduous nut trees. Carya illinoinensis, grown for its edible seed, is known as Pecan.

Description

Form: Tree.
Lifespan: 300 productive years.
Leaf retention: Deciduous.
Growth rate: Moderate.
Mature Size: 50-130' high and as wide.
Flowers: Separate male and female flowers are present on the same tree. Male flowers are catkins and develop at the end of last year's wood. Female flowers are short green tubes appearing at the end of new growth.
Bloom: Early spring. Pecan trees are subject to alternate bearing, where they produce a heavy crop one year, followed by a light crop the next.
Self-fruitful: Depends on cultivar. Pecan trees are wind pollinated and fall into two cultivar groups: those in which female flowers open before male flowers, and those in which female flowers open after male flowers. This sharply reduces self-pollination, except for a few cultivars where the blooms of male and female overlap and are self-compatible. For most cultivars, however, at least two compatible, but different, tree cultivars are needed for an abundant crop.
Years before fruiting: 5-10 for grafted trees, 10-15 ungrafted.
Fruit: A green, thin-fleshed, four-segmented husk covers a thin, hard, oblong shell (the endocarp) enclosing a seed called the pecan nut. When the seed is fully ripe, the husk turns brown and splits off the shell, allowing it to drop to the ground. Fruit that falls before becoming fully ripe is due to an overly heavy crop, or insufficient deep watering in previous months.
Months for fruit to ripen: 6.
Storage after harvest: Pecans must be quickly dried to 4.5% moisture before storage. Dried pecans may be refrigerated 1-2 years in a sealed container, with nuts in the shell lasting longer than shelled nuts.
Leaves: Green, curved leaflets with serrated margins.
Stems: No thorns. The bark is shaggy and shedding. Pecan branches may suddenly fall in summer if they receive too much shade and not enough sun. Heavy fruit loads will also cause old limbs to break off and fall.
Roots: Pecans are grown on rootstock selected for local soil and climate. In Arizona, rootstocks from New Mexico are used because California rootstocks are not well suited to the climate.
Cultivars of Note:
'Western Schley' Medium sized, good quality nut, thin shell, midseason, high yielding, self-fruitful, 250 chill hours, good in drier climates, lower nutritional needs than most pecans and easier to grow.
Wildlife: The flowers may attract non-pollinating insects. The seeds attract mammals and birds.
Toxic / Danger: Walnut family members produce the poison juglone, but pecan trees produce only small quantities. The tiny amount of juglone in pecan seeds usually does not bother animals but may cause gastric upset in dogs or laminitis in horses if eaten in sufficient quantities. Juglone produced by roots can cause harm to some species of plants growing nearby, such as apples, potatoes, and blackberries, that may need to be moved in favor of more juglone-tolerant plants. Pecan leaves are safe to compost.
Origin: The Mississippi river flood plain states plus river bottoms in Oklahoma, Texas, Kansas, and small parts of northern Mexico.

Cultivation and Uses

USDA hardiness zones: 6-10
Chill hours: 100-600 depending on cultivar. While budbreak may happen after a low chill winter, pollination problems are likely.
Heat tolerant: Yes with regular irrigation.
Sun: Full sun.
Drought tolerant: No.
Water after becoming established: Pecan trees are native to the Mississippi river region and need regular water. Use basin or flood irrigation every 1-2 weeks.
Soil: Well drained, moderate to high organic content. Pecans do best in soils with pH 6-7 (slightly acidic to neutral), but can tolerate a wider range of soils as long as they are well draining.
Fertilize: Apply zinc in late winter and compost late winter and early summer.
Mulch: Use organic mulch to reduce soil evaporation. Keep it 6-8" away from the trunk.
Spacing: Keep this huge tree at least 40' from any structure, wall, or other large plant. Pecans need good air circulation in their branches.
Planting: Avoid placing a pecan tree near any place cars park. In the fall, aphids feeding on sap from the leaves will drop a sugary residue on the ground underneath the tree.
First Year Care: After planting a dormant tree, cut back all branches by one-third. Then, after the branches have grown six inches, select one to be the central leader and cut back the others.
Prune: Prune pecan trees mid winter. Remove any dead or crossing branches and branches growing inward. The branches should be spaced to allow air to flow easily within the entire structure once leafed out.
Litter: Nut crop when not harvested, leaves in early winter.
Propagation: Grafted cuttings.
Uses: Edible nuts, shade.

Comments

The pecan is a huge tree needing a large amount of water and a vast yard. It is not really suitable as a residential tree except in its native, moderate rainfall, river bottom region.


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Latest update: July, 2019