Cashew Cultivation

CASHEW VARIETIES
 
There are three main varieties which are Brazilian cashew, Chinese cashew and Indian cashew. Brazilian cashew is mostly grown in Nigeria.


LAND PREPARATION AND PLANTING
 
Selection of planting material is most important in cashew cultivation. Cashew is highly cross pollinated and vegetative propagation is mainly recommended on commercial scale to produce true to type planting materials.

The field should first be cleared off its vegetation, after which it should be ploughed and harrowed. The nuts can be sowed 3 – 4 per hole or raised in nursery and transplanted in the field. After the establishment, the plants are thinned to one healthy and vigorous plant per stand.

Cashew can be propagated by seedlings, air layers and softwood grafts. Field establishment of air layers has been found to be poor. Hence softwood grafts, which give a high rate of establishment and early flowering, are recommended for planting


I. PROPAGATION BY SEEDLINGS

Selection of mother trees
 
Selected mother trees should be of Good health, vigorous growth and intensive branching habit with panicles having high percentage of hermaphrodite flowers. The trees should bear nuts of medium size and weight (5-8 g/nut) with an average yield of 15 kg nuts per annum and 7-8 nuts per panicle.

Selection of nuts

Select mother trees in February and collect seed nuts in March-April. Select good, mature, medium sized nuts.

Raising seedlings
 
Raise seedlings in polythene bags during May. Soak seed nuts in water for 18 to 24 hours to hasten germination. Sow the pre-soaked seed nuts in polythene bags filled with garden soil at a depth of 2-3 cm with the stalk end up. Seeds germinate in seven to ten days.


II. PROPAGATION BY AIR LAYERING
 
Prepare air layers during February-March, so that they will be ready for planting in June-July. Select 9-12 months old pencil-thick terminal shoots. Remove carefully a strip or ring of bark, 0.6 to 1.2 cm thick by using a sharp knife without injuring the underlying wood.

Wind a string around the cut area and cover it with moist moss or wood shavings or sand and saw dust mixture or ordinary potting mixture and wrap round with 150-200 gauge polythene film of size 23 x 15 cm.
Secure loose ends of film with jute fibre.

When roots emerge from the ringed portion in 40-60 days, give a ‘V’ cut at lower end of treated shoot. After about 15 days, deepen the cut slightly. Cut and separate rooted shoot about 7 days later. Pot the layers immediately after separation from the tree into containers of size 15 x 15 cm made from coconut husk and keep them in shade. Avoid excessive watering.

Plant the layers along with the container in the prepared pits with the onset of southwest monsoon. Provide shade and mulch with dry leaves to reduce sun-scorch in tender plants. It is advisable to defoliate the layers two weeks before separation from the mother plant.


III. PROPAGATION BY GRAFTING / BUDDING
 
Different methods of grafting which includes; epicotyl grafting, softwood grafting, veneer grafting, side grafting, patch budding etc. have been tried in cashew with varying degrees of success. Among them, softwood grafting was found to be the best for commercial multiplication of cashew.


SOFTWOOD GRAFTING & NURSERY MANAGEMENT

Production of scion sticks
 
The scion bank should be established with the recommended varieties of the region. The plants should be planted in a closer spacing of 4 m x 4 m, in order to get continuous supply of scions and fertilized with recommended quantity of NPK during monsoon and tender shoots should be protected by timely sprays of insecticides.

The flower panicles should be cut off in order to get more number of scions. Pruning of trees may be carried out annually during September–October in the scion bank.
 
Selection of scion and precuring
 
Select non-flowered, 3-5 month old lateral shoots of current season’s growth. The selected scion sticks should be precured by clipping off leaf blades, leaving petiole.

The scion sticks can be detached from the mother tree after 8-10 days, before they sprout and utilized for grafting.
 
Collection of scion stick
 
Scion sticks should be dipped in water and placed in a polythene bag of 100 guage thickness and brought to the nursery shed for grafting. The scion sticks wrapped in sphagnum moss cloth and placed in a polythene bag of 100 guage can be kept for 3-4 days and used for grafting, if necessary.

Selection of seed nuts
 
Fresh seed nuts should be collected during the peak period of harvest in February-March and sun dried for 2-3 days. Medium sized nuts of 7-9 g should be selected in order to get uniform and vigorously growing seedlings required for soft wood grafting.

The sun dried, graded seeds should be treated with carbaryl (5g/Kg of seeds) before storing them in gunny bags or polythene bags.

Preparation of potting mixture
 
Prepare the potting mixture in the proportion of one part red soil, one part sand and one part compost in heavy rainfall areas and one part red soil, one part compost in low rainfall areas and mixed with little quantity of rock phosphate (10g/2Kg of potting mixture).

Sowing of seeds
 
The seednuts should be soaked in water for 12-24 hours before sowing in order to get good germination. At the time of sowing the soil should be moist and loosened in the polythene bag. Sow the seeds at a depth of not more than 2.5 cm and cover with little soil.

The seednuts usually germinate within 15-20 days after sowing. Seed bed may be mulched with paddy straw till germination takes place and partial shade may be provided during summer months. To control pests while seeds germinate, malathion 5% dust, or spraying of chloropyriphos (durmet 20 EC: 0.05%) should be applied.

Grafting
 
• The wedge of the scion is inserted into the cleft of the root stock to see that the cambial layers of both the root stock and the scion come in perfect contact with each other.

• The graft joint is secured firmly with 2.5 cm wide and 30 cm long polythene strip of 100 gauge thickness.

• A long and narrow HD polythene bag of 15 cm x 12.5 cm size and 100 gauge thickness is inserted on the grafted plant, tied at the bottom with a single knot in order to protect the scion stick from drying up.

• In places with high humidity the polythene cap need not be used.

• The freshly grafted plants are left in the nursery shed for about two weeks to encourage sprouting of the terminal buds.

• After two weeks the polythene caps are removed gently and the grafts are shifted to open condition in the nursery.

• Within 3-4 weeks, 70-80% of the grafts will sprout.

• Graft ready for planting within 5-6 months.

• The success in softwood grafting is more during the period from March to September under Kerala conditions.










 
MANAGEMENT OF CASHEW GRAFTS IN THE NURSERY
 
• Cashew grafts should be watered daily during dry periods.

• During rainy season, excess water should be removed.

• Plants in the nursery should be shifted at least once in a month to avoid penetration of roots in the ground.

• During summer months (January-May) grafted plants should be protected by providing partial shade by erecting pandal of dry coconut fronds or nylon nets.

• Bordeaux mixture spray (1%) may be given at 10 days interval during rainy season to control fungal infection of tender seedlings and grafted plants.

• Ekalux (1.5ml/litre of water) may be sprayed to control sucking insects and leaf eating caterpillars as and when the damage is seen.

• The flower panicles produced by the graft should be removed as and when observed in the nursery.

• The polythene strip should be removed from the graft joint after four months of grafting.

• The bottom leaves on the root stock should be removed after three months of grafting when scion leaves turn bronze colour to green.


MANURING
 
A fertilizer dose of 750 g N, 325 g P2O5 and 750 g K2O per plant is recommended for cashew. Apply 1/5th dose after the completion of first year, 2/5th dose during second year and thus reaching full dose from 5th year onwards.

Broadcast the fertilizer within an area of 0.5 to 3.0 m (15 cm deep) around the tree and incorporate by light raking.


INTERCROPPING
 
Pineapple is the most profitable inter-crop in cashew plantation in the early stages of growth. It can be planted between two rows of cashew in trenches opened across the slope.

Cashews can be inter cropped with arable crops such as soybean, cowpea, groundnut, melons and vegetables for some years.

It is not advisable to inter-crop cashew with corns because the crops can grow taller than the seedlings and cast shadows on them. The crops can also cause significant removal of soil nutrients.


PLANT SPACING
 
A spacing of 7.5 m x 7.5 m has been recommended for poor soils, and for rich, deep and coastal sandy soils a wider spacing of 10 m x 10 m is prescribed. In sloppy regions, the rows may be kept 10-15 m apart and the distance between trees within a row can be maintained between 6 and 8 m.


PEST AND DISEASE CONTROL
 
The young plants should be protected against tea mosquito bug and stem borer using eco-friendly strategies. The tea mosquito bug can be repelled by smoking the garden with organic residues during flushing, flowering and fruiting seasons, and by resorting to spraying with Pongamia oil (2 per cent) during the same phases of development.

The use of bio-control agents such as weaver ant may help in checking the tea mosquito bugs.


WEEDING
 
Manual and chemical weeding can be practiced. Manual weeding can be done at the seedling stage but after full establishment, herbicides can be used in the plantation. Contact herbicide is recommended, but the spray must not touch the leaves

Apply glyphosate 0.8 kg/ha, once in June-July. Depending upon the weed growth, weeding operation may be done during August-September.


HARVESTING

The fruits will be ready for harvest in about two months after fertilization of the flowers. The ripe fruits will drop off to the ground, which can be collected manually. The nuts can be separated from the apple, dried for two days and stored till they are dispatched to the markets.

The apple must be harvested and processed immediately because it is highly perishable and gets spoilt within few hours. It can be eaten fresh or processed into juice.

The nuts must be well dried in the sun before they are bagged and stored. Well dried nuts can be stored more than a year before they are shelled or sold.