178 DISEASES OF TROPICAL PLANTS CH . 



starting on decaying material it can readily spread to 

 the living tissues. The destruction of stumps, roots, 

 and decaying material in general will be helpful in con- 

 trolling this disease. Trenching and liming are also said 

 to be helpful. Young plants should never be set where 

 others have died from this disease. 



Since writing the above Fetch has reported R. 

 bothrina as occurring on tea and other plants in India. 

 It spreads from the roots and stumps and frequently 

 will not grow on related plants. 



Internal Root Rot. This disease has been reported 

 from Assam, and is due to Diplodia vasinfecta, Petch. 

 Like most root diseases, it first attracts attention by a 

 discoloration of the leaves, which become yellow and 

 fall, followed by the death of the tree. The fungus 

 lives within the roots and seldom comes to the surface. 

 The fruits are rarely formed. It is supposed to be 

 carried by the seeds. 



Up-Country Root Disease. This disease has been 

 reported from India, and is due to Poria hypolateritia, 

 Berk. Petch describes it as follows : 



This fructification forms a white or pinkish patch, studded 

 with minute holes, extending for several inches over the stems, 

 or even surface of the soil. Beneath the comparatively soft 

 white tissues is a red horny layer which gives the fungus its 

 distinctive name. This red layer is often formed inside decaying 

 stumps, and may be taken as a sure sign of the presence of this 

 fungus when no real fructification is to be found. This fungus 

 appears to be common on dead logs in the up-country jungles. 



Low-Country Root Disease. This disease has been 

 reported from India, and is due to an undescribed 

 species of Ustulina. 1 The mycelium works between 

 the wood and the bark, forming white or yellowish fan- 

 shaped patches which become black on the edge when 

 they come in contact with a crack in the bark. A cross 

 section of the root shows numerous irregular black lines. 

 The sporophores are formed on the lower part of the 

 trunk and protrude from cracks in the bark. They 



1 This is probably U. zonata, a fungus which also occurs on pomolo and 

 coco-nut, although it is probably saprophytic on the latter. 



