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

Black root disease

The causal organism Rosellinia bunodes (B. & Br.) Sacc & Rosellinia arcuta Petch

Classification
Class- Ascomycotina,
Order- Sphaeriales
Family- Xylariaceae.
Though the disease has been reported on coffee, but its spread & severity is limited unlike the brown & red root disease.

Symptoms

• Aerial symptoms are almost the same as described under brown root disease. On affected roots, black fungal rhiozomorph or black woolly mycelium are seen. In transverse section, thread like black lines or dots can be seen clearly.
• On the stem near the ground level, fan shaped black fungal mat with pellet like fructifications are also seen.
Management
• Isolate the infected plants from one row of apparently healthy adjoining plants by digging 60cm deep & 30cm wide trench. The soil from the trench should be thrown into affected area & not outside.
• Uproot the infected coffee plants along with the root system & burn.
• Add agricultural lime @ 1-2 kg per pit after uprooting the plants & keep the land fallow for 6 months before planting.
• Whenever a shade tree is felled, it is advisable to uproot the stumps completely so as to avoid the infection due to brown root disease in future.
• Drench the soil with carbendazim 50 WP @ 0.4%/plant in the initial stage of the disease during pre & post monsoon period.
• Application of well composted organic manure @ 10-15 kg per plant would also help in suppression of pathogens.
• Soil application of 3-5 kg of the mixture of bioagent Trichoderma in compost to the infected coffee plants in drip cycle during Sept-Oct & May-Jun in a year has been found effective.