microbe responsible for brown rot
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Answer:
Root Diseases
A number of root diseases have been reported in cocoa. Rarely do these diseases cause any substantial damage to the crop. Different pathogens are known to cause the root diseases. Their primary source of inoculum comes from forest trees cleared prior to planting or infected shade trees. The above-ground symptoms of all root diseases caused by different pathogens are sudden wilting of the leaves of the tree followed by death of the plant. However, root diseases can be identified by the presence of fruiting bodies present on the roots or on the collar region of the affected plant. Root diseases have so far not been reported from India. The major root diseases are:
1.
Brown root disease: Phellinus noxius (Fomes noxius)
2.
White root disease: Rigidoporus lignosus (Fomes lignosus)
3.
Black root disease: Rosellinia pepo Pat.
4.
Collar crack: Armillaria mellea Vahl.
The spread of the diseases can be checked by the removal of infected plants, including roots. Digging trenches around the infected tree is also recommended. The infected plants with their roots should be removed and burned. There is no recommendation for chemical control of the disease, except that the cut surfaces of all stumps of cocoa and shade trees should be painted with an aboricide, such as sodium arsenite or 2,4,5-T, at the time of felling to kill the stumps. If 2,4,5-T is used, a 3 percent solution of copper fungicide should be added.