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CHAPTER IX 



iSO 



Fig. 52 



acterized by the leaf sheath becoming red, the red coloration spreading 

 all over the sheath and shading off into an orange colour. The disease 



passes from the leaf sheath to the stem, 

 attacking the soft parts near the nodes. 

 At a late period of development the 

 affected parts are covered with an abun- 

 dant mucous mycelium, and eventually 

 a large number of sclerotia, the size of 

 a pin's head, are produced. These are 

 at first white and eventually become 

 yellow and brown. The diseased parts 

 have a smell of mushrooms. It is 

 young cane that is most often attack- 

 ed, and in the case of tops the germina- 

 tion of the eyes may be prevented. 

 The disease has been reported from 

 Java, St. Croix, Porto Rico, Cuba, Barbados and Jamaica. 



Acid Rot of the Leaf Sheath J ^ — This disease much resembles the one de- 

 scribed above. It is distinguished by the lighter red colour of the infected parts, 

 by the larger-sized orange sclerotia and by the odour of apples. The disease 

 does not readily pass to the stem, and then only attacks young internodes. 



Cane Rust. Puccinia kuhnii (Kriiger), (Butler). — Soris uredo- 

 sporiferis hypophyllis linearibus ; tiredo-sporis e globoso ellipsoideis 

 pyriformibus, contentu aurantico, exosporio copiose aculeato, hyalino, 

 18 — 34 .5 X 28* 5 — 57' 5 ; pedicello hyalino, clavato, suffuUis. 



Various forms of these spores, after Kriiger, are 

 shown in Fig. 52. In this disease narrow orange-coloured 

 stripes appear on the leaf, especially on the underside, 

 and from these stripes an orange-coloured dust can be 

 scraped. This serves to distinguish this disease from 

 other leaf diseases. The rust is composed of the spores 

 of the fungus. In Java, whence it has alone been re- 

 ported, the disease is everywhere present in damp dis- 

 tricts, but the damage done is small. Butler has recently 

 found a second stage of this fimgus on Saccharum spon- 

 taneum in Burma which shows it to be a Puccinia, not a 

 Uredo, as it was formerly called. 



Leaf-splitting Disease.''^ — This disease, which is per- 

 haps confined to one district in Hawaii, is characterized 

 by a number of yellow stripes appearing on the leaves, 

 which afterwards split and wither. Cobb considered the 

 disease due to an organism, Mycosphcerella striatiformans , 

 but did not prove the connection by inoculation experi- 

 ments. Similar manifestations are reported from Fiji and 

 the Argentine, and as early as 1849''^ Bojer described a 

 similar appearance in Mauritius, attributing it to electrical 

 influences in the atmosphere. 



Wither Tip.''^ — This disease, reported from Hawaii, is 

 characterized by the ends of the leaves withering, the 

 midrib remaining green after the rest of the leaf is dead. It 

 from Porto Rico. 



