Introduction

Cashew (Anacardium occidentale L.) is a commercially important tropical nut crop grown primarily for its delicious edible kernel, called the cashew nut. It also yields Cashew Nut Shell Liquid (CNSL), which has industrial applications. India is among the leading producers and exporters of cashew globally.

Origin and Distribution

• Botanical name: Anacardium occidentale
• Family: Anacardiaceae
• Chromosome number: 2n = 42
• Origin: Eastern Brazil (South America)
• Introduced to India: By the Portuguese in the 16th century for soil erosion control along coastal belts
• Global Producers: India, Vietnam, Nigeria, Ivory Coast, Brazil
• Major States in India: Maharashtra, Kerala, Karnataka, Goa, Andhra Pradesh, Odisha, Tamil Nadu, West Bengal, and Chhattisgarh

• Major Cashew Growing Countries: India, Vietnam, Nigeria, Ivory Coast, Brazil
• Cashew Growing States in India: Maharashtra, Kerala, Karnataka, Goa

Climate Requirements

Cashew is a tropical crop and thrives in warm and humid climates.

• Temperature: Optimal range is 20°C to 35°C
• Rainfall: 1000–2000 mm annually
• Altitude: Grows well up to 700 m above sea level
• Sunlight: Requires bright sunlight; cannot tolerate frost
• Dry Spell: A dry spell of 2–3 months before flowering is beneficial for good flowering and fruiting

Soil Requirements

• Ideal Soil: Well-drained sandy loam, red lateritic, or coastal sandy soils
• Soil pH: 4.5 to 6.5
• Soil Depth: Minimum of 1–1.5 m depth is required for good root penetration
• Drainage: Proper drainage is essential; waterlogging is detrimental
• Salinity and Alkalinity: Cashew is sensitive to saline and alkaline soils

Varieties

State-wise Important Cashew Varieties in India

• Tamil Nadu Varieties (TNAU); VRI-1, VRI-2, VRI-3, VRI-4, VRI (CW) H1
•  Kerala Varieties (KAU) Akshaya, Amrutha, Anagha, Anakkayam-1, Dhana, Dharasree, K-22-1, Kanaka, Madakkathara-1, Madakkathara-2, Priyanka, Sulabha, Mrudula, Poornima, Sree, KAU Nihara
•  Andhra Pradesh Varieties (Bapatla Centre); BPP-1, BPP-2, BPP-3, BPP-4, BPP-5, BPP-6, BPP-8, BPP-10, BPP-11
•  Karnataka Varieties (UAS, NRCC Puttur); Chintamani-1, Chintamani-2, NRCC-1, NRCC-2, Ullal-1, Ullal-2, Ullal-3, Ullal-4, Bhaskara, Nethra Vaman
•  Maharashtra Varieties (Vengurla Station); Vengurla-1 to 8
•  Goa Varieties; Goa-1, 2
• Odisha Varieties; Bhubaneswar-1, Jagannath, Balabhadra
•  West Bengal Varieties; Jhargram-1, Jhargram-2

Propagation Methods

Cashew can be propagated through seeds or vegetative means.

• Seed Propagation
• Seeds from elite mother trees are sown directly
• Results in variability in yield and nut quality
• Used in the past, now mostly replaced

• Vegetative Propagation
• Softwood grafting (most common)
• Epicotyl grafting (done on seedlings 7–10 days old)
• Air layering, cuttings, and budding (less common)

Planting

• Time of Planting
• June–July (Kharif) is the best time, coinciding with the onset of the monsoon

• Pit Preparation
• Size: 45 cm × 45 cm × 45 cm
• Filling: Topsoil mixed with 10–15 kg FYM, 1 kg neem cake, and some sand for drainage

• Spacing
• Normal Spacing: 7 m × 7 m (approx. 200 plants/ha)
• High-Density Planting: 5 m × 4 m (500 plants/ha) – pruning is essential

Training and Pruning

• Training: Develop a single stem up to 1 m height
• Pruning: Remove dead, diseased, or cross branches after harvest (May–June)
• Helps in improving light penetration and aeration

Nutrient Management

• Fertilizers are applied in two split doses: before monsoon and after fruit set

Irrigation

• Mostly rainfed, but drip irrigation improves yield in dry areas
• Critical stages: Flowering and fruit development
• Irrigation Frequency: Once in 7–10 days during dry spells

Intercropping

• During early stages (up to 3 years), intercropping is practiced
• Suitable intercrops: Groundnut, cowpea, black gram, vegetables
• Helps in income generation and weed control

Pest and Disease Management

• Major Pests

• Diseases

Flowering and Fruiting

• Begins from third year, economic yield from 7th year onward
• Flowering Season: December to January
• Pollination: Mainly by insects (entomophilous)
• Fruit Set to Harvest: 60–70 days
• Fruit Type: Drupe (nut) + pseudo fruit (cashew apple)

Harvesting and Yield

• Harvesting Period: March to May
• Nuts fall naturally to the ground when mature
• Collect nuts daily to avoid quality loss
• Average Yield:
  • Normal orchard: 8–10 kg nuts/tree/year
  • Improved orchards: 15–20 kg/tree/year

Post-Harvest Processing

• Processing Steps:

1. Roasting

Purpose: Makes shells brittle.

• a) Open Pan Roasting
• Traditional method
• Nuts heated on metal pan over fire
• Causes shell charring and brittleness
• No longer used in organized sectors

• b) Drum Roasting
• Cleaning → Remove impurities
• Pre-treatment → Steam softens shell
• Roasting:
  • Use rotating drum at 160–180°C for 30–60 mins
• Cooling → Rapid cooling to stop roasting
• Shelling, Peeling, Grading, Packing follows

• c) Oil Bath Roasting
• Nuts held in wire trays and dipped in cashew shell oil bath at 200–202°C for 3 mins
• Shell oil released and recovered through overflow
• Nuts then centrifuged to remove oil
• Mixed with wood ash and shelled
• Panruti (Tamil Nadu) uses sun drying and hand shelling

Moisture Conditioning / Humidifying

• Ensures proper roasting quality
• Nuts sprinkled with water and kept for 24–48 hours
• Final moisture: 15–20%

Precautions:

• Water must not penetrate testa
• Water must be iron-free (iron can react with polyphenols causing discoloration)

2. Shelling

• Done manually using wooden mallets
• Careful to avoid breaking kernel

3. Peeling

• Remove testa using safety pin or knife
• Made easier by 4-hour drying in heated chamber

4. Sweating

• Kernels spread on cement floor to absorb moisture
• Reduces brittleness, prevents breakage during grading

5. Grading

• Based on visual characteristics: wholes, splits, broken
• 25 exportable grades
• Size grading by number of kernels/lb
• Mostly manual, size grading can be mechanized

6. Packing

• Kernels packed in 10 kg tins
• Evacuated and filled with CO₂ for preservation

• By-Products:
• Cashew Apple: Used for juice, wine, vinegar, and feni (Goan liquor)
• Cashew Nut Shell Liquid (CNSL): Used in paints, lubricants, plastics