📈 Diseases of Papaya and Other Tropical Fruits

Papaya (Carica papaya) is a fast-growing tropical fruit crop widely cultivated across India. It is highly susceptible to viral, fungal, and bacterial diseases. Other tropical fruits like sapota (chiku), jackfruit, and custard apple are also affected by specific pathogens.

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Diseases of Papaya

Papaya Ring Spot

Causal Organism: Papaya Ring Spot Virus (PRSV) — a Potyvirus

This is the most destructive disease of papaya worldwide.

Symptoms

• Dark green rings and spots on the fruit surface (characteristic ring pattern)
• Mosaic pattern, leaf distortion, and shoe-string appearance of leaves
• Water-soaked streaks on petioles and stems
• Reduced fruit size, quality, and overall plant vigour

Transmission

Transmitted in a non-persistent manner by several aphid species, principally Aphis gossypii and Myzus persicae.

Management

• Plant tolerant varieties such as Pusa Nanha or transgenic varieties where permitted
• Rogue out infected plants immediately to reduce inoculum
• Use barrier crops (maize or sorghum) around the papaya field to impede aphid flight
• Spray Imidacloprid to control aphid vectors

Papaya Leaf Curl

Causal Organism: Papaya Leaf Curl Virus (PaLCuV) — a Begomovirus

Feature	Detail
Vector	Whitefly (Bemisia tabaci)
Transmission	Persistent, circulative
Symptoms	Downward curling and crinkling of leaves, vein thickening, stunting
Severity	Plants become unproductive when infected early

Management

• Control whitefly with yellow sticky traps and Thiamethoxam sprays
• Remove and destroy infected plants promptly
• Maintain weed-free fields to eliminate alternate virus hosts

Foot Rot and Stem Rot

Causal Organism: Phytophthora palmivora and P. nicotianae

Symptoms

• Water-soaked lesions at the base of the stem near the soil line
• Darkening and softening of the stem leading to toppling of the plant
• Fruit rot with watery, foul-smelling decay in waterlogged conditions

Management

• Ensure good drainage and avoid water stagnation around the root zone
• Apply Metalaxyl-Mancozeb (Ridomil MZ, 0.2%) as soil drench and stem spray
• Raise beds to improve drainage in heavy soils
• Avoid injuries to the stem during field operations

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Diseases of Other Tropical Fruits

Sapota (Chiku) — Sooty Mould

Causal Organism: Capnodium spp. (grows on honeydew excreted by mealybugs and scales)

• Black, velvety coating on leaves and fruits
• Reduces photosynthesis and fruit marketability
• Control the insect vectors (mealybugs, scales) with Dimethoate or neem oil
• Wash sooty mould deposits with starch solution (1%) followed by water spray

Jackfruit — Rhizopus Fruit Rot

Causal Organism: Rhizopus stolonifer

• Soft, watery rot of ripe fruits with white-grey fungal growth
• Post-harvest disease favoured by warm, humid storage conditions
• Handle fruits carefully to avoid wounds; cold storage at 10-13 degrees C reduces rot

Custard Apple — Diplodia Fruit Rot

Causal Organism: Diplodia natalensis

• Brown, dry rot beginning at the stylar end of the fruit
• Affected tissue becomes dark brown and hard
• Spray Mancozeb (0.25%) before fruit maturity to reduce infection

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Summary Cheat Sheet

Crop	Disease	Hallmark Symptom	Core Management
Papaya	Ring spot (PRSV)	Dark green fruit rings and shoe-string leaves	Rogueing + vector control + barrier crops
Papaya	Leaf curl	Downward curling and stunting	Whitefly suppression + clean fields
Papaya	Foot/stem rot	Basal stem water-soaked decay	Drainage + Metalaxyl-Mancozeb drench
Other tropical fruits	Sooty mould/fruit rots	Black mould or post-harvest soft rot	Vector control + careful handling + preventive sprays

References

2 sources • [1] [2]

[1]

Indian Council of Agricultural Research (ICAR)

Official

[2]

CABI Crop Protection Compendium

Website