📈 Diseases of Banana — Panama Wilt, Sigatoka, Bunchy Top

Banana (Musa spp.) is a staple fruit crop grown across tropical and subtropical regions of India. The crop is affected by several devastating diseases, with Panama wilt, Sigatoka leaf spot, and bunchy top being the most significant.

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Panama Wilt (Fusarium Wilt)

Causal Organism: Fusarium oxysporum f. sp. cubense (Foc)

Symptoms

• Yellowing of older leaves starting from the margins, progressing to the midrib
• Leaves break at the petiole and hang down, giving a "skirt" appearance
• Longitudinal splitting of the pseudostem base
• Internal cross-section shows reddish-brown discolouration of vascular bundles
• Plants wilt and die before producing marketable fruit

Disease Cycle

The fungus is soil-borne and persists as chlamydospores for over 30 years. It enters through roots and colonises the xylem vessels. The disease spreads through infected planting material, contaminated soil, and irrigation water. Tropical Race 4 (TR4) is the most aggressive strain and threatens Cavendish cultivars globally.

Management

• Use disease-free tissue-cultured plantlets
• Practice long crop rotation (5-7 years) with non-host crops
• Apply biocontrol agents such as Trichoderma viride and Pseudomonas fluorescens to the soil
• Resistant cultivars include Poovan (Mysore), Nendran, and Karpuravalli

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Sigatoka Leaf Spot

Banana Sigatoka includes two forms — Yellow Sigatoka and Black Sigatoka.

Feature	Yellow Sigatoka	Black Sigatoka
Causal organism	Mycosphaerella musicola	Mycosphaerella fijiensis
Lesion colour	Yellow to light brown	Dark brown to black
Severity	Moderate	Highly destructive
Distribution	Worldwide	Tropics, increasingly global

Symptoms

• Small, pale yellow streaks on leaves that enlarge into elliptical spots
• Spots coalesce and cause extensive leaf necrosis
• Reduced photosynthetic area leads to smaller bunches and premature ripening

Management

• Remove and destroy severely infected leaves
• Spray Propiconazole (0.1%) or Mancozeb (0.25%) at 15-day intervals during the rainy season
• Maintain adequate spacing to improve air circulation
• Resistant cultivars such as Poovan and Karpuravalli show moderate tolerance

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Bunchy Top

Causal Organism: Banana Bunchy Top Virus (BBTV) — a single-stranded DNA virus (Nanoviridae)

Symptoms

• Leaves become narrow, erect, and form a tight rosette or "bunchy" appearance at the crown
• Dark green "Morse code" streaks along leaf veins and petioles
• Infected plants are severely stunted and never produce fruit
• Marginal chlorosis with characteristic wavy leaf edges

Vector

Transmitted by the banana aphid (Pentalonia nigronervosa) in a persistent, circulative manner.

Management

• Eradicate infected plants immediately by injecting herbicide into the pseudostem
• Use virus-free tissue-cultured planting material
• Control aphid vector with Imidacloprid (0.3 ml/L) or Dimethoate
• Establish disease-free nursery zones away from infected plantations

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Summary Cheat Sheet

Disease	Causal Organism	Hallmark Symptom	Core Management
Panama wilt	Fusarium oxysporum f. sp. cubense	Vascular browning and plant collapse	Clean planting material + rotation + biocontrol
Sigatoka	Mycosphaerella spp.	Leaf streaks/spots leading to necrosis	Leaf sanitation + fungicide schedule
Bunchy top	BBTV	Rosette "bunchy" leaves and severe stunting	Rogue infected plants + aphid management

References

2 sources • [1] [2]

[1]

Indian Council of Agricultural Research (ICAR)

Official

[2]

CABI Crop Protection Compendium

Website