Diseases of fruit plantation medicinal and aromatic crops (2+1)

Bunchytop of Banana

Causal organism: Banana bunchy top virus
Also called as cabbage top disease, it was first recorded in Fiji in 1889. In Cavendish banana and local plantations. Bunchy top disease was observed in Indian states Assam, Bombay, Kerala, and Tamilnadu in 1940

Symptoms

• The infected leaves show green streaks on the secondary veins on the under side of lamina, midrib and petiole
• The powdery bloom covers midrib and petiole, the dark green lines with ragged edge appear if rubbed
• Leaves remain dwarf, they also show marginal chlorosis and curling. The leaves are brittle in texture and petioles incompletely elongated
• The leaves become smaller and eventually the crown of the plant become composed with stunted growth, the rosette or bunchy leaves
• Fruit bunches are reduced, lower hands of the bunch often die down


Etiology

• Virus is semi- persistent in nature, aphids(Pentalonia nigronervosa f.sp. cocquerelli) act as vector
• Virus particles are isometric and 18-20 nm in diameter, having acquisition feeding period as 2- 4 hours , incubation period as 6-8 hours with inoculation period 2-4 hours.
Mode of spread and survival

• Primary source of inoculum: infected plants and suckers.
• Secondary source of inoculum: Vector- borne virus particles, spread more in summer through aphids.
Epidemiology

• The disease is spreading very quickly in hill zone, as the hill banana is cultivated as a perennial crop and the aphid population in hill areas is more due to conducive atmosphere in these areas.
Management

• Selection of healthy planting materials
• Regular field visits, removal of infected plants and suckers at periodical intervals
• Select disease free area for new plantations
• Avoid excess application of nitrogen, apply recommended dose of potassium and FYM.
• Proper drip irrigation in summer season is required
• Chemicals: For aphid control, application of monocrotophos with banana injector @ 1.2 ml/lt. Suckers planted in the field, pits should be treated with 40 gm of carbofuran granules
• Application of dimethoate (rogor) @2ml/ lt in the soil
• Capsule application of 2, 4 D.
• FERNOXONE (5 ml) is injected into the pseudo stem.