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Cashew

Introduction

In the Philippines, cashew is called kasoy or balubad in Tagalog or Balogo in Ilokano. It originated from north-eastern Brazil and was brought to the Philippines in the 17th Century. At present, cashew is cultivated in many tropical countries, the main producers are Brazil, India, Mozambique and Tanzania.

The cashew plant is an evergreen tree that grows up to 12 meters tall, with a dome-shaped crown or canopy bearing its foliage on the outside, where flowers and fruits are found.

The growth of the taproot reaches a depth of 1.5-2 times the height of the plant during the first 4 months. Extensive lateral roots are formed later and reach far beyond the canopy spread of the tree during the first year of growth. In mature trees, the root volume is generally confined within the tree canopy. Very few laterals are formed beyond the 6 meter drip-line of the tree.

The fruit has a kidney-shaped nut, about 3 cm x 1.2 cm attached to a much enlarged and swollen pedicel or receptacle forming the fruit-like cashew apple. The cashew apple is pear-shaped, 10-20 cm x 4-8 cm, shiny, red to yellow, soft, and juicy. The seed is kidney-shaped, with reddish-brown testa, two large white cotyledons, and a small embryo. The kernel remaining after the removal of the testa is the cashew nut of commerce.

Favorable Growing Conditions

It can grow successfully in areas with a very distinct dry season or where the annual rainfall is as low as 50 cm. It can likewise grow well in areas with high levels of rainfall (as much as 350 cm annually) provided the soil is well-drained.

Seed System

  1. Nursery Site
  2. The nursery site should be well-drained and exposed to sunlight. It should have a good source of irrigation water for the maintenance of the plant materials. It should be protected against stray animals.

  3. Nut Selection
  4. Nuts for planting should be obtained from mother trees of known performance. They should be fully matured and of high density (heavy) grade to ensure good germination and vigorous seedlings. Seeds are water tested; those that sink are chosen since they have higher viability and germinate quickly.

  5. Sowing the Seeds
  6. Cashew seeds expire easily. Dry and newly collected seeds must be sown/propagated as soon as possible to prevent loss in viability. They are sown on individual polyethylene bags containing an equal mixture of fine sand and organic matter.

    Seeds are sown 5-10 cm deep with stalk end facing upward in slanting position. This prevents the emerging cotyledons at the soil surface from being destroyed by rats, ants, snails, and birds.

  7. Care of Seedlings
  8. Seeds will germinate within 1 to 2 weeks after sowing. Excessive watering should be avoided. If seedlings are week and stunted, urea solution at the rate of 10 tbsp per gallon of water should be applied.

    The seedlings must be properly taken care of until they are ready for field planting or for use in asexual propagation (grafting). Seedlings are ready for field planting when they have attained a height of 20-50 cm.

  9. Propagation
  10. Cashew can be propagated sexually or asexually. Asexual propagation can be done through airlayering, inarching, marcotting or grafting. Grafting is the best method for large-scale asexual propagation of cashew.

    With cleft grafting, the seedlings are cut in traverse section (crosswise) and the remaining stem is cut longitudinally (lengthwise). The scion from a selected mother tree cut into the shape of a wedge is put between the two separated parts of the stem of the seedling, and the seedling and the scion are then wrapped with a plastic ribbon.

    Up to 100% success has been obtained with 10-week old seedlings. In Palawan, plant propagators can get an average of 95% success in cleft grafting.

    The use of young seedlings of about two months old result in more rapid takes, and the plants are ready to be planted at the age of 3 ½ months.

    Sexual propagation is done by sowing the seeds directly on individual polyethylene bags. It should be done during the dry season so that the seedlings could be planted in the field at the start of the rainy season.

Land Preparation

For commercial purposes, the land should be thoroughly prepared. Plow the area 2-3 times followed by harrowing until the desired tilth of the soil is attained. It should be done before the start of the rainy season. For backyard or reforestation purposes, just underbrush the area and if possible collect all cut grasses, shrubs, and other rubbishes and burn them. The soil should be cultivated properly in order that the seeds may be sown with the required depth or that holes may be dug deep enough to bury the ball of seedlings. Rows of cashew trees should be properly laid out with the proper distancing by placing markers at the desired distance between hills in a row before digging the holes.

Crop Establishment

  1. Distance of planting
  2. Distance of planting varies according to the purpose for which the trees are planted. For reforestation, 3m x 3m is recommended to encourage early shading and to aid in smothering weeds.

    For commercial plantings in the Philippines use 6m x 6m which is too close compared to the practice in other countries.

    Triangular planting was found to be most productive layout and should be tried. This method, however, is rather difficult for farmers to follow.

    High density planting gives more kernel per hectare up to age 7 years. Low density planting gives less per hectare but more per tree.

    1. Triangular (12m x 12m x 12m) = 79 plants/ha
      An alternative and easier method is the quincunx arrangement and should also be tried.
    2. Quincunx (15m x 15m) = 76 plants/ha
    3. Square
      The simplest recommended planting distances are 9m x 9m at the less fertile lower slopes and 10m x 10m at the more fertile lower slopes.
  3. Lining, Stacking and Digging of Holes
  4. Rows of cashew should be properly laid out by placing markers between rows and between hills in a row.

    The holes should be dug a month before the planting of seedlings. The holes should have a dimension 20 cm x 20 cm.

  5. Planting Time
  6. In places with distinct dry and wet seasons, planting is best done at the start of the rainy season.

  7. Planting
  8. There are two methods of establishing cashew that may be employed. These are direct seeding and transplanting of seedlings or sexually propagated materials.

    In direct seedlings, 2 to 3 seeds are planted 5-10 cm deep with the stalk end facing upward and in a slanting position. This prevents emerging cotyledons at the soil surface from the ravages of field rats, ants, snails and birds.

    Seeds are planted 30 cm apart in a triangular position when 3 seeds are used. The seeds will germinate 1-2 weeks after sowing provided that the soil has sufficient moisture.

    Thinning should be done leaving only the most vigorous plant to develop 1-2 months from germination. Thinning is preferably done during the start of the rainy season.

    When transplanting seedlings or sexually propagated materials, remove carefully the polyethylene plastic before setting the seedlings in the holes.

    Fill the holes with surface soil first and firm the soil at the base of the seedling carefully allowing the roots to remain in as natural as possible.

  9. Weeding and Cultivation
  10. The plants should be cultivated and free from weeds at a distance of 1 meter around the trunk. The orchard should be weeded as often as necessary. Cut grasses should be left in the area between the hills to dry and to used later for mulching. Mulching helps conserve moisture around the plant during the summer months, keep down the weeds and increase the amount of humus in the soil when decays.

  11. Intercropping and Covercropping
  12. A considerable part of the land is available for intercropping during the early years after the establishment of the cashew orchard.

    To provide sufficient protection from the heavy growth of weeds and grass, the spaces between rows may be used for planting cash crops. This would enable the grower to earn additional income.

    Annual crops can be interplanted between rows of cashew provided they are not closer than 2 meter from the cashew tree.

    When the growing of intercrops is no longer feasible, the field should be planted to leguminous covercrops. The planting of covercrops will prevent further soil erosion, conserve moisture, and add organic matter to the soil. The area within 1 to 1 1/2 meters from the trunk should be kept free from weeds and covercrops should not be allowed to cling to the tree.

  13. Pruning
  14. Little pruning is practiced in cashew. However, it may be necessary to prune regularly to get the desirable shape of the tree and to facilitate cultural operations.

    It is also necessary to remove the diseased and infected branches and unnecessary water sprouts.

  15. Cut wounds should be properly treated with chemicals (coaltar) to facilitate healing and avoid infections.