ANTHRACNOSE

Anthracnose

    Causal organism:Colletotricum gloeosporioides

    • The causal organism is classified under the
      • Class- Deuteromycotina,
      • Order- Melancoloniales,
      • Family- Melanconiaceae.

    The disease affects the leaves, twigs and berries. It is a bark inhabiting fungus, a weak pathogen but under certain conditions of the host & the environment becomes virulent.
    The fungus causes three different diseases of coffee viz., twig die back, stalk rot of berries & leaves & brown blight of leaves.
    a. Twig die-back or summer die-back
    This disease occurs during dry weather from Oct-May and reaches to its peak level after blossom showers.

    Symptoms

    • Yellowing or blighting of leaf on the green wood.
    • Yellowing, necrosis of nodes & internodes towards the tip.
    • Infected twig wilts and kills necrosis of tissues towards the apex and depict a die-back appearance.
    • Floral buds on infected branches fail to open.
    • Infected plants put on new vegetative growth on the primary & secondary near the main stem.
    • Infected plants in the exposed area bear new leaves which are small, crinkled, chlorotic, thick and leathery.
    • Internodes are short and give fan shape appearance.

    Favourable factors

    • Debility of twigs or branches due to defoliation caused by heavy incidence of leaf rust,
    • Susceptible crop strain, inadequate over head shade, prolonged drought & soil moisture stress are the pre disposing factors for the disease development.
    • The fungus invades debilitated branches under conditions like low temperature, mist or dew during night & early hours.

    Management

    • Pruning of badly affected plants during Feb-Mar.
    • Maintaining adequate overhead shade to protect the bushes from sun scalding & mulching of leaf litter around the plants for conserving soil moisture during dry weather.
    • Application of balanced nutrients to maintain vigour of the plants.
    • Protect plants by spraying 0.5% Bordeaux mixture during Feb- Mar(Pre-blossom), Apr-May (Pre-monsoon) & Sep-Oct (Post-monsoon).

Last modified: Monday, 13 February 2012, 6:41 AM