Family: JUGLANDACEAE
The pecan belongs to the same botanical family as the walnut and also belongs to the same genus as the hickory, with which it is cross fertile. It is a native of North America, and although it was introduced to Australia many years ago, it only became a commercial crop in the early 1970's. Pecans are long - lived trees and grow as tall as 100 m. They begin to bear nuts at 6 - 7 years of age and reach maturity at 15 - 20 years. A mature tree can produce up to 50 kg of nuts, but 20 - 30 kg is more usual.
Nutritional composition of the pecan per 100 grams of edible portion is: Water - 3.4%, Energy - 687 calories, Carbohydrate - 14.6 g, Fat - 71.2 g, Protein - 9.2 g, Ash - 1.6 g, Calcium - 73 mg, Potassium - 603 mg, Sodium - trace, Magnesium - 142 mg, Iron - 2.4 mg, Phosphorous - 289 mg, Vitamin A - 130 I.U., Thiamin - 0.86 mg, Riboflavin - 0.13 mg, Niacin - 0.9 mg, Ascorbic acid - 0.9 mgs and the digestion time is 2.75 hours.
Pecans prefer long summers and appear to grow best where the summer temperature range is within 24 - 30oC, although no extensive research has been carried out on temperature require-ments. Some winter chilling is necessary to set fruit but the pecan is sensitive to frosts during the growing season. Different cultivars require different lengths of growing season, so selection of a suitable variety is important. In areas where the growing season is 230 days or more, choice of cultivars is unlimited. The pecan grows naturally in areas of high humidity, but it has been found that pollination is better where humidity is lower. Pecans need an abundance of soil moisture, but rainfall at flowering and harvest times can lower production, as can wind or hail storms.
Pecans will grow on a wide range of soils, providing they are fertile and well drained, with a good water holding capacity. Neutral soils are preferable, but a pH range of 6 - 8 will be tolerated. They will not grow on soils that are at all saline.
The pecan has both male and female flowers on the same tree and is wind pollinated. It is also self - fertile, but better quality nuts are produced when cross - pollinated. Different cultivars should be planted together to ensure adequate pollination.
Pecans are usually budded or grafted onto seedling rootstock, the most popular being Riverside and Apache.
Traditionally, orchards were planted at 15 m x 15 m although with newer cultivars, 5 m x 10 m or 7.5 m x 7.5 m is the more usual spacing.
Pruning consists of removing weak, dead or broken branches, and branches that cross or are otherwise wayward. The tree produces fruit on its new growth, so extensive pruning will result in lower yields. In older trees, some pruning will be required to stimulate growth and maintain production.
The pecan is susceptible to very few pests and diseases in Australia as yet, the main problem being parrots and cockatoos.
Cultivars
There are over 500 cultivars of pecan in existence, although many of these are no longer commercially grown. Some of the more important ones are: