THE PESTS AND DISEASES OF THE CANE. 



Nat Size 



FIG. 69. 



Indies by Howard and Lewton-Brain. Here adult cane is usually affected, 

 particularly ratoons ; the roots are attacked, and the cane dies from 

 want of water. After rains the toadstool is often found growing at the 

 base of the cane. Wakker's technical description of this fungus is Gregoria 



vel bati fasii-culata, diver sa, carnoso-membranacea 

 persistentes ; pileus albus late-campanulatus dein 

 sordide albus, planus vel cupuliformis, 15 mm. diam.; 

 lamellae albae simplices vel bifurcatae. Stipe* 

 centrahs albus, long. 15 mm. apice tubiforme base 

 villosa. HypJiae albae. Sporidia hyalina, continua^ 

 irregulariter-oblonga utrinque atienuaia 16 W x 

 4 5. Habitat in caulibus vivis. This organism 

 or one closely related also occurs in Hawaii, and 

 has been provisionally named M. sacchari, var. 

 Hawaiiensis. A marasmius is also, according to 

 Fulton, 35 parasitic on cane in Louisiana, and is- 

 identified as M. plicatus, which has been observed 

 as a saprophyte in Java. In Fig. 69 is shown the 

 toadstool of this fungus as appearing in Hawaii^ 

 and in Fig. 70 the spores, both after Cobb. 



3. Top Rot or PokJca Song. The etiology of this disease is considered 

 uncertain by Went and Wakker. It has been connected with Cobb's Gumming 

 Disease, but later researches, especially those of Erwin Smith, 36 indicate that 

 these diseases, whilst somewhat similar in outward appearance, are totally 

 distinct. 



Three stages may be recognized in the disease. In the first the young 

 leaves become yellow, wither and die, while the internodes, being unable to 

 obtain food, remain short and stunted ; in the second stage the young leaves 

 that have opened roll up and die ; in the third stage the vegetative point is 

 changed to a slimy pulp, the remainder of 

 the top being filled with a slimy substance 

 possessing a foul smell similar to but distinct 

 from that associated with the Ustilago sacchari. 

 Later the eyes underneath the top shoot 

 and may form almost a new top. Young 

 plants a few months old are more often 

 affected than mature cane, and continued 

 rain is a predisposing cause. On an estate 

 with which the author was connected in Demerara, a rot, outwardly the 

 same as the one in question, was very prevalent, and he made the following 

 observations : Older canes frequently suffered, but there was always previous 

 insect damage of the top. In young canes of age from a few days (i.e., when 

 the eye was sprouting) to two or three months the apical leaf was frequently 



FIG. 70. 



143 



