THE PESTS AN T D DISEASES OF THE CANE. 



In Fig. 80 is shown (after Butler) a cane stem attacked by this fungus, 

 and in Fig. 81 the spores, also after Butler. 



10. Black Rot c * g . Sph&roncema adiposum. Butler. An organism described 

 under this name has been found by Butler in India, associated with Thielaviopsis 

 ethaceticus, and Butler has succeeded in infecting healthy canes with this 

 organism. His description of it is: Sphceroncema 

 adiposum. Mycelio dense lanoso, atro ex hyphis brunneis, 

 ramosis composite ; hyphis fertilis simplicibus, septatis, 

 endoconidiis gerentibus ; endoconidiis polymorphis, 

 cylindraceis, pyriformis vel globosis, aliis hyalinis vel 

 brunneis, Zevibus, aliis fuscis verrucosis, 925x fa 5 - 18 ; 

 peritheciis globosis, pilosis, atris in cottum erectum, 

 rigidum, 26 m.m. X 50 microns, productis, ore sub- 

 fimbriatis; sporidiis hyalinis, continuis, crasse lunulatis, 

 utrinque acutis 6'5 X 3'5, muco adiposo obvolutis. Sab. 

 in culmis sacchari officinarum, India. Fig. 82 shows 

 a cutting infected with this fungus. 



11. The Maladie de la Gomme, or Gumming 

 Disease of Mauritius, has been described, as far as 

 external appearance is concerned, by Boname. At 

 first there is nothing abnormal in the appearance of 

 the cane, but when the disease ia fully established 

 growth is stationary and the leaves turn yellow. If the stem is cut trans- 

 versely, small masses of a yellow viscid matter appear on the cut surface, 

 which dry and harden in the air. This gum is only found in the central fibro- 

 vascular bundles, and not in the sacchariferous cells. A 

 gum, however, which is not yellow is also found round 

 the knots and on the upper portion of the stem. In the 

 final stage of the disease the extremity of the stem 

 decays, the internal portion being filled with a grey 

 viscid substance. 



x 250 



FIG. 81. 



Diseased specimens of canes were forwarded to 

 Prilleux and Delacroix, 49 who found on these canes an 

 organism which they identified with Coniothryrium 

 melasporum. This organism is the same as Darluca melas- 

 porum, found by Berkeley on Porto Rican canes, and is 

 indentified by Howard with the Dipljdia cacaoicola. The 

 description of Boname agrees very closely with the 

 appearance due to gumming as described by Cobb, and 

 it is, of course, possible that the organism found by 



Prilleux and Delacroix was in a sense accidental, and not the cause of the 



disease. 



/Yafural -S/2t 



FIG. 82. 



151 



