Diseases of coffee and their control
coffee leaf rust
small pale-yellow spota on the lower surface of infected leaves, orange-yellow spore mass appears, defoliation and die-back. Results in serious crop loss and causes fluctuations in production.
3 applications of 0.5% Bordeaux mixture for susceptible varieties.
Black rot(koleroga roxia)
blackening and rotting of affected leaves, young twigs and berries. Affected leaves get detached and hang down by means of slimy fungal strands. Defoliation and berry drop occur.
Remove and burn affected parts. Apply 1% Bordeaux mixture close to the south westerly monsoon if needed. Centre the coffee bushes, regulate the overhead canopy.
A weak parasite but becomes vigorous under favourable environmental conditions. causes 3 diseases:
provide good drainage to remove excess water from the root zone. Spray with 0.5% Bordeaux mixture to prevent defoliation., maintain adequate shade to avoid sunscald.
Root rots (Fusariumspp.)
1.stump or brown root-rots: affected bushes show a gradual yellowing of leaves and defoliation and death. Affected roots are brittle and show dark brown wavy lines of the fungus.
Burn the plants at site, isolate affected patches by digging deep trenches, ring the bark and poison the shade trees while thinning., remove the affected plants and treat the soil at 1kg lime per plant to raise the soil pH. treat the soil around the affected area with PDCB or brassicol at 0.4%. Maintain the vigour of plants.
neorotic spots on the exposed surface of green berries enlarge and cover the major portion. fruit skin shrivels and sticks fast.
spray 1% Bordeaux mixture during june and late august, maintain medium shade overhead.
nursery disease (collar rot or damping-off)
pre=emergent damping off in germinating beds. Collar rot in primary or secondary beds. Seedlings show wilting, rotting extends from the collar all around and seedlings collapse.
Apply brassicol 0.4% or terrachlor or rhizoctol or Flit406 or ferbam or dithanr m22 0.4%. Maintain good shade and sanitation. Remove and burn affected seedlings.
Brown eye spot.
usually severe in the nursery but found on young coffee plants also, small circular neorotic spota appear with dark brown margin and pale white centre. Leaves turn yellow and are shed.
spray nursery seedlings with 0.4% flit 406 and young coffee plants with 1% Bordeaux mixture during april-may and sept-oct, avoid exposing the plants to direct sun.
kondli or stem wasting (disorder)
A non-parasitic disorder. A constriction of the main stem, tendency towards lean and lanky growth and the main stem snaps off at the constricted portion.
avoid application of copper fungicides to nursery seedling especially in inclement weather during june-august