Climate
Cashew is essentially a tropical crop, grows best in the warm, moist and typically tropical climate. The distribution of cashew is restricted to altitudes below 700 m where the temperature does not fall below 200C for prolonged periods, although it may be found growing at elevation up to 1200 m. It is best adopted to the coastal regions. The cashew is hardy and drought resistant, but it is damaged by frost.
Rainfall
Cashew is grown in areas with rainfall ranging from 600 – 4500 mm per annum. Fruit setting in cashew will be good if rains are not abundant during flowering and nuts mature in a dry period.
Temperature
Cashew is a sun loving tree and does not tolerate excessive shade. It can tolerate temperature of more than 360C for a shorter period but the most favourable temperature lies between 24 C to 28 C.
The climatic factors influence the cashew growth and production as follows:-
Dry spell during flowering and fruit setting ensures better harvest.
Cloudy weather during flowering enhances scorching of flowers due to tea mosquito infestation.
Heavy rains during flowering and fruit set damages production.
High temperature (39-420C) during stage of fruit set development causes fruit drop.
Soil
Cashew is an hardy crop. It can be grown on a wide range of soils except heavy clay, water logged and saline soils. Well drained red, sandy and laterite soils are ideal for good growth and yield of cashew.
Varieties
Selection of suitable cashew varieties for the specific region and appropriate package of practices determines the final yield. More than 30 varieties which are having exportable grade of cashew kernels are released from different research institutes in India and details are furnished separately.
Planting material
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. Softwood grafting is the only method which is commercially feasible and practically highly successful in cashew.
Spacing
The normal recommended spacing is 7.5 x 7.5 m to 8 x 8 m and spacing may be reduced up to 4m x 4m depends on type of soil and managerial capacity.
The high density planting consisting of up to 625 plants/ha can also be adopted for better utilization of space during early years. Initial planting can be done at a spacing of 4mts x 4mts or 5mts x 5mts or 6mts x 4mts and maintained up to a period of 7 to 9 years with proper pruning and training. Later the excess plants can be thinned out to provide a final spacing of 8mts x 8mts or 10mts x 10mts or 6mts x 8mts.
Method and season of planting
The square system of planting can be followed. The ideal time for planting is usually during monsoon season when the moisture is air surcharged (June-August) both in the west coast and east coast. If irrigation facilities are available, planting can be done throughout the year except winter months.
Normally cashew grafts are planted in the pits of 60 cm. cube. It is preferable to dig the pits at least 15-20 days before planting and expose to sunlight so that termites and ants, if any, which damage the roots of the grafts will migrate elsewhere. The pits should be completely filled with a mixture of top soil and organic manure to ¾ of the pit capacity. The grafts are planted after carefully removing the polythene bag. Care should be taken to see that the graft joint remains at least 5 cm above the ground level at the time of planting. The polythene tape around the graft union need to be removed carefully. Staking should be done immediately after planting to protect the grafts from wind damage. Mulch the basins of plants with organic waste materials during early years.
Application of manures and fertilizers
Manures and fertilizers promote growth of the plants and advance the onset of flowering in young trees. Application of 10-15 kg of farm yard manure or compost per plant is beneficial. The current fertilizer recommendations for cashew is 500 g N (1.1 kg urea), 125 g P205 (625 g rock phosphate) and 125 g K2O (208 g Muriate of potash) per plant per year. The ideal period for fertilizer application is immediately after the cessation of heavy rains and with available soil moisture. During the 1st, 2nd and 3rd year of planting 1/3rd, 2/3rd and full doze of fertilizers should be applied and 3rd year onwards full quantity is to be applied.
Weeding
Clearing the area by manually within 2mtr radius of the trunk and slashing the remainder is essential until the trees shade out most of the trees. Weeding can be done by chemically also. Glyphosate (post emergent) application at 6 to 7 ml per litre of water (0.8 kg a.i./ha) during June – July also effectively controls weeds.
Mulching
Mulching the tree basins will help in conservation of soil moisture and prevents soil erosion. Mulching with organic matter or residues inhibits weed growth and reduces surface evaporation during summer and also regulates the soil temperature.
Under sloppy areas, soil and water conservation practices can be done by making trenches of 30 cm width, 60 cm depth. And convenient length may be taken in between rows along the contour. This will mot only conserve soil and moisture but will also enable to enhance the growth of cashew.
Training and pruning
Training and pruning is the important horticulture practice to be employed to make better frame work of cashew plant. It helps to control growth and make easy for cultural practices. The sprouts arising from the root stock portion of the cashew graft should be removed frequently during the first year of planting. As an orchard management technique to improve the sanitation, removal of water shoots, lower branches, crisscross branches and dry branches are found to be beneficial to enhance flowering and the yield.
Irrigation
In India cashew is grown mainly under rain fed condition. However protective irrigation especially summer months during January-march at fortnightly intervals @ 200 liters/plant improves fruit set, fruit retention, thereby increasing nut yield.
Intercropping
Intercropping received little attention in the cashew. However, depending on soil and climatic conditions and local situations annual vegetables like tapioca, pulses, turmeric, ginger etc, can be grown as inter crops. When once the plants become sufficiently big pepper can be taken as mixed crop.
Plant protection
Tea mosquito, stem borer, thrips, leaf minor and leaf blossom webber are important pests of cashew. Of these, tea mosquito and stem borer causes economical damage in cashew.
Tea mosquito: Tea mosquito bug (Helopeltis antonii s.) can cause yield reduction to the tune of 30-40 per cent damaging tender shoots, inflorescence and immature nuts at various stages of development. It attacks the tree in all the seasons during flushing, flowering and fruit setting period but the peak period of infestation is from October to March. To control the pest, spray schedule involving three sprays synchronizing new flushing (October-November), flowering (November-December) and fruit setting (January – February) may be given with the following chemicals:-
Quinalphos (25% EC) - 0.05%
Carbaryl (50% WP) - 0.01%
Phosphamidon (85% WSC) - 0.03%
The number of sprays should be limited to three and the same insecticide should be used for the subsequent sprays.
Stem and root borer - Stem and root borer (Placaederus ferrugineus L.) is also a dangerous pest and kill the entire plant. It is mostly seen in neglected gardens. The larvae of a beetle tunnel into the tree trunk and eats the bark all around the trunk. Manual removing of grubs and pasting the damaged portion with mixture of Carbaryl 50 gm (50%) and copper Oxychloride (25 gm) in one liter of water give effective control.
Harvesting and yield
The flower panicles emerging from the graft during 1st and 2nd year should be removed in order to allow the plant to put good vegetative growth and better framework. Economic bearing in cashew commences after 3rd year of planting. The ripened will fall down and nuts from fallen fruits have to be collected. Nuts can be dried in sun for 2 to 3 days on cement floor and can be stored in gunny bags. The yield starting from 1 kg in 3rd-4th year, yield goes on increasing as the canopy develops and one can expect more that 10 kgs. of nuts in 8 to 10 years old plant depending on management.
Marketing of raw cashewnuts
Marketing of raw cashewnut in India has not yet been organized in systematic manner except in Goa where co-operative marketing society is procuring raw nuts to the little desired extent. A major portion of the produce is brought by itinerant merchants and the agents of the processing units. A number of wholesale merchants and the processing factories open their collecting centres in important cashew producing areas during the harvesting period. The petty dealers who buy the nuts from the growers also dispose the nuts in these collecting centres. Cashewnut are brought for sale to the assembling markets largely by the itinerant merchants. In certain areas, the most resourceful processors contact the producers thus avoiding the commission agents role and enjoy good bargaining power by providing credit facilities to the producers.
As there are a number of intermediaries operating the field between the primary producer and the processing unit. The different costs and margins in the total spread between the producer and the processing unit are quite significant and the producers share in the price paid by the processing units generally low.
