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/fr.... [Accessed 31 March 15]. Free to access.




Common Pests and Diseases

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.

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.

Mealy bug (Grape mealy bug, citrophilus mealybug, striped mealybug)
Pseudococcus maritimus
Pseudococcus calceolariae
Ferrisia virgata

Symptoms
The insect infect all parts of the plant. Both nymphs and adults suck the sap from the leaves, flowers and fruits,resulting in yellowing of leaves, curling and shedding of flowers and tender fruits. Also the market value of such fruits reduced. In dry season insect can invade roots and suck sap. Due to honey dew secretion sooty mold may develop on leaves and fruits.
Cause
Insect
Comments
Polyphagous insect. Female can lay 300 to 400 eggs in soil. Short life cycle (40 days).
Management
Spraying soap solution reduces mealy bug population. Encourage natural enemies. If the infestation is severe apply suitable insecticide.

Aphids (cotton aphids)
Aphis gossypii

Symptoms
Both adults and nymphs suck sap from growing shoots, flowers and young fruit. Heavy infestation leads to stunting or week tree. Sooty mold and soft rot may develop on the fruit.
Cause
Insect
Comments
Aphids are carried by ants from one plant to another.
Management
Encourage natural enemies. Keep the field free from crop debris and weeds. Spraying strong jet of water to dislodge the aphid. If infestation is severe spray suitable insecticide.

Leaf-footed plant bugs
Leptoglossus clypealis

Symptoms
Both adult and nymphs feeds by penetrating their mouth parts to the thick skin of the pomegranate fruit to the arils resulting in withering of stung arils.
Cause
Insect
Comments
The insect have wide host range.
Management
If the infestation is severe apply suitable insecticide.

Omnivorous leafroller
Platynota stultana

Symptoms
Larvae enter the fruit by craving surface grooves, especially where the two fruits touched. It causes tunneling in fruit. Due to the skin damage secondary pathogens may infect the fruits and resulting in rotting.
Cause
Insect
Comments
Insect lay eggs on weeds near the field in the off season.
Management
Keep the field free from weeds. Remove the infected fruits and burn them. Use pheromone trap to kill adult insects.

Pomegranate fruit borer (Anar butterfly, common guava blue butterfly)
Virachola isocrates

Symptoms
The female butterfly lay eggs on tender leaves. After hatching the larvae feeds on fruit by boring hole. The damaged fruit rots and emits a foul smell. One can see the excreta of larvae near the hole. The final stage larvae come out of the hole and pupate by spinning the web.
Cause
Insect
Comments
The life cycle of insect is completed in 1 to 2 months. Very common pests in Asia.
Management
Remove the damaged fruit and burn them. Grow available resisting varieties. If infestation is severe spray suitable insecticide.

Citrus Flat mite
Brevipalpus lewisi

Symptoms
Suck sap from fruit surface resulting in skin russeting, checking or leathery skin. This leads to reduce in market value of fruits. The citrus flat mite damage starts from the stem end of the fruit.
Cause
Mite
Comments
Mites are very small and difficult to trace them. If you use hand lens can see mites and their cast skins in the cracks of damaged fruits.
Management
Application of sulfur before and after flowering reduces the mite population.