Diseases of Fruit Plantation Medicinal and Aromatic Crops

Dieback of Jackfruit

Causal organism: Botryodiplodia theobromae
SYMPTOMS
• Discoloration and darkening of the bark from the tip downwards.
• It advances and young green twigs start withering from the base towards veins of leaf edges.
• Infected leaves turn brown with their margins rolling upwards.
• Infected twigs or branches shrivel due to necrosis and fall down, there may be exudation of gum from affected branches which may then attacked by shoot borers causing internal discoloration of the twigs.
• On infected twigs, erumpent aceruvuli of Colletotrichum gloeosporioides can be seen.
ETIOLOGY

• Pycnidia are asexual fruiting bodies, up to 5mm in diameter. Conidia are asexual spores, thin walled at first which become thick walled and septate mycelia are present.
• Primary source of inoculum: Dormant mycelia
• Secondary source of inoculum: Soil and airborne conidia.
EPIDEMIOLOGY

A Temperature of 25⁰ C -30⁰C low relative humidity (80- 85%), and presence of susceptible hosts favours the development of the disease.

MANAGEMENT

• Pruning of infected twigs followed by spraying with carbendazim (0.1%) or thiophenate methyl (0.2 %) or chlorothaloni (0.2%) have been recommended.
• Controlling shoot borer and shoot hole borers with suitable insecticides is also important in reducing die back disease.