Cashew

Cashew : Variety:A81, A82, A100 and A75/83.

1. Cashew Botany 

  • The tree is small and evergreen, growing to a height of 10 - 12m.
  • The leaves are spirally arranged, leathery textured elliptic to obviate.
  • The flowers are produced in a panicle or corymbs of upto 26 cm long, each flower small,  pale green at first then turning reddish, with five slender, acute petals of 7 - 15 mm long.
  • The fruit is an oval or pear - shaped structure that develops from the pedicel and the receptacle of the cashew flower called the cashew apple
  • Within the true cashew fruit (apple) is a single seed, the cashew nut.
  • The seed is surrounded by a double shell containing resin, anacardicacid, a potent skin irritant chemically.
  • The tree starts to bear after one and half years (1.5 yrs) but the economic yields are after three years
  • KALRO has developed 14 varieties with a potential of an average of up to 50 kgs per tree.
  • Kenya produces about 15,000 tonnes annually.

2.         Recommended zones

Cashew does well in tropical climate with high and constant temperature. It can be grown in elevations of 0–1,000m above sea level, with the ideal being 600m.It is grown by smallholder farmers within the coastal region and was recently introduced in Meru and Tharaka Nithi Counties. Cashew requires temperatures of 24–28oC, with the optimum being 27oC, but it can thrive even in 40oC.Rainfall should be 800–1600mm per year, followed by 4–5 months of  ample sunshine for the cashew to flower and ultimately give a good yield. Excessive humidity leads to fungal diseases. Cashew prefers deep soils (more than 2m) that are well-drained and light-textured, e.g., sandy soils. It does not grow well in heavy clay, compact and hard soils, hard pans, soils with concretions in the rooting zones, and soils found in valleys, flood plains and swampy areas due to their poor drainage. The optimum range of pH for growing cashews is 4.5–6.5, with the minimum being 3.8. The tree is not tolerant to saline soils.

3.         Management Practices

a)         Planting specifications

Cashew is usually propagated through seeds or grafted seedlings. Grafted seedlings are available in KALRO nurseries and in some of their private partner institutions.

b) To establish a cashew orchard, the following steps are recommended:

  1. Plough the land.
  2. Lay out the field by spacing holes at 12m x 12m.
  3. Dig holes one or two months before planting. The measurements of the holes should be 60cm x 60cm x 60cm.
  4. Carefully remove the seedling from the polythene bag so as to not disturb the roots.
  5. Plant the seedling at the centre of the hole.
  6. Prepare a shallow basin around the seedling.
  7. Cover the area with mulch before watering.
  8. Water the plant every 3–4 days.

c) Recommended fertiliser rates

Animal and compost manure are the best fertilisers for cashew. However, if manure is not available and intensive production is carried out, chemical fertilisers, such as Diammonium Phosphate (DAP), Calcium Ammonium Nitrate (CAN) and Potassium Sulphate can be applied.

Fertilizer and manure rates for Cashew

Year

Fertilizer type and quantity/tree

Manure

(10 kg debe)

DAP

(g)

CAN (g)

Potassium Sulphate (g)

Long rains

Short rains

Long rains

Short rains

Long rains

Short rains

I

2

1

260

180

180

40

40

II

2

1

520

360

360

80

80

III

2

2

780

540

540

125

125

Above III years

2

2

780

540

540

125

125

d) Managing old cashew orchards

The following options are available for improving old cashew orchards depending on their condition.

Pruning

Pruning is done to remove unwanted plant parts.

Selective thinning

This is removal of unwanted trees from the orchard.                                     

Pollarding

Pollarding is severe pruning of the tree at a height of about 3m to reduce canopy to allow easier spraying and harvesting.

Coppicing

Coppicing is cutting down the tree at a height of 1.5 m to 2 m to renew the canopy.

Top-working

Top working is grafting of sprouts from unproductive coppiced trees. Top-work 3-4 sprouts per stem.

e) Disease and pest management

The most notable pest that affects cashews is the cashew nut bug. Other insect pests include stem borers, thrips, mealybugs, weevils, caterpillars and leaf miners. Diseases that affect cashews include powdery mildew and anthracnose. The following are important pests and diseases of cashew found in the Coast.

Diseases

Symptoms

Control/Treatment

Powdery mildew

  • Mildew (ash white covering) occurs on tender leaves, young shoots, flowers
  • Flowers are most susceptible
  • Seriously attacked flowers die in a few days
  • Can cause over 80% loss of yield
  • Common in cool and cloudy weather

Spray with Bayfidan at a rate of 10-15 ml in 3 litres of water per tree per application. Start spaying at onset of flowering and apply 3 times at 14 days intervals.

Anthracnosis

 

  • Attacks all tender parts of cashew
  • Black spots appear on attacked parts
  • Concentric rings on apples

Spray with any of the following:

Antracol

Kocide DF

Before & after flowering

Remove diebacks before spraying

Pests

Symptoms

Control/Treatment

Cashew nut bug

 

  • The bug is orange in colour
  • Lays eggs on young twigs.
  • The bug causes heavy damage to seedlings
  •  Sucks sap from young leaves, shoots and young nuts and apples

Spray with Lebacid

Harvesting and Post-harvest handling

Harvesting starts from November and extends to May.  The peak is November-December.

  • Clear the area beneath the tree
  • Collect fallen fruits
  • Detach the nut from the apple
  • Dry under the sun for about 2 hours

Grade into Fair Average Quality (whitish) and Under Grade (blackish).