Diseases of Fruit Plantation Medicinal and Aromatic Crops

Leaf spot

Causal organism: Cercospora spp.
SYMPTOMS

• Brown colored spots appear on lower surface of the leaf.
• Disease is severe in neglected crops in which blightening and leaf falling occurs.
  
Etiology

• Septate mycelia,
• Inter cellular mycelia and intracellular haustoria.
• Asexual spores- whip like conidia on conidiaphores,
• Sexual spores- Ascospores borne in ascus inside the Pseudothecium
• Vegetative structure is dormant mycelia.
Epidemiology

• Temp 30-320C, RH 85-90 per cent, cloudy weather, poor management.
• Source of inoculum
• Primary source of inoculum: Dormant mycelia.
• Secondary source of inoculum: Air borne conidia.
Life cycle

• Pseudothecium is the primary source of inoculum formed in the infected debris.
• In favourable climate it produces ascospres and cause primary infection.
• In the infected host whip like conidia are present on conidiophore that cause the asexual infection.
• During adverse climatic conditions, the fungus reproduces by sexual method where antheridium and ascogonium are formed.
• After gametangial contact plasmogamy, karyogamy, mitosis followed by meiosis and ascospore formation takes place.
Management

• Collect the older leaves and burn.
• Avoid high density plantation.
• Proper nutrient management of the soil.
• Spray with Mancozeb @( 2g/lit).