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

Inflorescence die back

Causal organism: Colletotrichum gloeosporioides Penz.
Symptoms

• Die back of inflorescence is associated with low fruit set. About 60% of palms in the state of Karnataka and Kerala are infected by this disease causing severe shedding of buttons.
• Disease appears on the rachillae of the male flowers, then in the main rachis as brownish patches which soon spread from tip downwards covering the entire rachis causing it wilting. The female flowers of the infected rachis are shed.
• The fungus also infects the developing embryo inside the female flowers, which eventually shrivels up showing a brown discoloration.
• Under severe conditions the fungal infection proceeds from tip downwards producing the condition known as die-back.
• Concentric rings of light pink coloured conidial mass of the pathogen appear on the discolored portions of the infected inflorescence.
Etiology

• Mycelium is septate , asexual spores are the conidia borne in acervulus.
• Ascospores are the sexual spores borne in Perithecium.
• Primary source of innoculum: Dormant mycelia.
• Secondary source of innoculum: Conidia.
Epidemiology

• The disease is prevalent throughout the year, but is most serious during the dry period (Feb-May).
• Temperature requirement is 28-32?C with relative humidity of 90-92% and presence of weak host.
Life cycle
Management
• Summer irrigation
• Recommended N:P:K application/plant.
• Spray Carbendazim (0.1%)