Diseases of Fruit Plantation Medicinal and Aromatic Crops

Inter root disease

Causal organism: Botryodiplodia theobromae Pat.

• The disease usually appears within six weeks to three months after pruning.
• The roots of a dead bush do not bear any external mycelium.
• In some cases the bark becomes rough and abnormally thickened.
• The mycelium runs within the tissues of the plant. The fructifications of the fungus are minute, black, spherical bodies embedded in the bark.
• Fructifications are not visible externally. When bark is slightly scrapped, the spheres are cut across and black circles with white centre may be seen.
• The fungus enters through the fine rootlets and attacks the tap root also. Soil fumigation is the best method to control it, though it is expensive.
• It is the most suitable method to prevent further spread of the disease in young and high yielding mature tea bushes.
• Replanting can be done after 12 weeks as against 24 months of rehabilitation following uprooting of the dead and suspected plants.
• Vapam and metham sodium may be applied into an apparently healthy ring of bushes, 20 to 25 cm away from the collar region of the living plant to avoid phytotoxicity. Dueofume C.P. (methyl bromide + ethylene dibromide 1:1) which is supplied in 450 g ca. s is enough to fumigate 526 sq.feet.
• Isolation drenches (120 cm deep and 45 cm wide) may be dug around the infected bushes to isolate them and prevent further spread of the disease.
• Lime should be added in the affected patch and also in the trench.
• The shading trees should be pruned to permit more sunlight. Digging up of dead and infected stumps, bushes and burning them to reduce the spread.
• Adequate manuring should be done to keep the bushes in vigorous condition.
• The cut ends of branches after pruning may be sprayed with Bordeaux mixture (1.0%) to prevent infection.