Pomegranate

Description

Pomegranate, Punica granatum, is a deciduous or evergreen tree or shrub in the family Punicaceae grown for its edible fruits. The pomegranate tree is branched and spiny with glossy, leathery, oval to oblong leaves that grow in whorls of five or more on the branches. The tree produces bright red flowers singly at the tips of the branches and a rounded hexagonal fruit with a thick pink-red skin. The fruit has a thick, leathery rind which protects the pulp[ and seeds inside. The inside of the fruit is separated into compartments by white spongy tissue. Each compartment contains seeds and pulp. Each pomegranate fruit may contain as many as 600 seeds. Pomegranate trees can reach a height of 10 m (33 ft) and can be very long lived, although their economic lifespan is usually between 12 and 15 years. Pomegranate may also be referred to as grenadine or Chinese apple and originated from Central Asia, likely in Iran.


Uses

Pomegranate is primarily eaten as a fresh fruit by splitting open the rind and consuming the seeds. The seeds may be used in salads. The fruit may also be used to produce juice, either by removing and pressing the seeds or by pressing the whole fruit.


Propagation


Basic requirements
Pomegranates grow best in temperate or semi-arid climates with a cool winter and warm summer. They are less hardy than many other deciduous fruit trees but more hardy than citrus. Pomegranates will suffer severe damage when temperatures drop below -10°C (14°F). Pomegranate can be grown successfully on a range of soil types, including calcareous soils and acidic loam but will grow optimally in deep, well-draining loam.

Propagation
Commercial pomegranate trees are propagated from softwood and hardwood cuttings as seeds will not breed true to type. Hardwood cutting are generally preferred over softwood due to the ease with which they root. Hardwood cuttings are taken from shoots or suckers from the previous season and are rooted in nursery beds after treatment with a rooting hormone. Cuttings are grown in the nursery for one season before being planted out in the orchard. Rooted cuttings are best planted in winter or early spring and are usually spaced 3.5–5.5 m (11.5–18 ft) apart. The young trees are headed back to a height of 60–70 cm (23–28 in) after planting to promote branching.

General care and maintenance
Pomegranates have a similar water requirement to citrus trees and should be provided with additional irrigation during dry periods. Pomegranate orchards usually utilize drip, furrow or sprinkler irrigation systems to promote optimal yields. Pomegranates can be pruned to a single stemmed tree or allowed to grow as a multi-stemmed bush. Suckers should be removed from around the central trunks as they develop. Pomegranates will benefit from the addition of nitrogen. Nitrogen should be applied at a rate of 0.2–0.5 kg per tree each year. Pomegranate fruits are usually thinned to promote the production of larger fruits

Harvesting
Pomegranate fruits are generally ready to harvest between 6 and 7 months after flowering, fruits should be allowed to mature fully on the branch prior to harvest as they will not continue to ripen off of the tree. Fully mature fruit turn bright red in color and make a metallic sound when tapped. Fruits should be harvested by cutting from the tree.


References

CABI Crop Protection Compendium. (2012). Punica granatum (pomegranate)) datasheet. Available at: http://www.cabi.org/cpc/datasheet/45931. [Accessed 31 March 15]. Paid subscription required.

Stein, L., Kamas, J. & Nesbitt, M. (2010). Pomegranates. Texas A&M AgriLife Extension. Available at: http://aggie-horticulture.tamu.edu/fruit-nut/files/2010/10/pomegranates.pdf. [Accessed 31 March 15]. Free to access.




Common Pests and Diseases

Cercospora fruit spot
Cercospora punicae

Symptoms
Light brown spots on leaves and fruit which enlarge and coalesce to form large black patches on fruit; black elliptical spots appear on twigs and become flattened and depressed with a raised margin; infected twigs dry out and die; infection may cause plant death
Cause
Fungus
Comments
Disease emergence is favored by rainfall and water saturated soil
Management
Diseased fruits should be removed and destroyed; infected twigs and branches should be pruned out; applications of appropriate fungicides can help to control the disease

Heart rot (Black heart)
Alternaria spp.

Symptoms
Interior of fruit rotting with no external symptoms; infected fruits are usually lighter in weight than healthy fruits and may be paler in color
Cause
Fungi
Comments
May be linked to moisture levels at time of flowering
Management
No known method of control