CANE SUGAR. 



association is debatable ; means for the enforcement of its recommendations 

 are necessary however, lest the carelessness of a few individuals destroy the 

 whole object of its existence. 



Fungus Diseases.* The diseases due to fungi are numerous and 

 collectively cause annual losses of enormous sums ; they have been studied 

 amongst others by Kriiger, "Went and Wakker in Java, by Howard and 

 Lewton-Brain in the West Indies, by Cobb in Queensland, by Cobb and 

 Lewton-Brain in Hawaii, by Barber and Butler in India, and at Kew by Massee. 



The most prominent diseases are the Sereh of Java, the Rood Snod of 

 Java, which is cosmopolitan and is best expressed in English as Red Rot of the 

 Stem, the Rind Fungus of West Indies, the etiology of which is still imperfect, 

 the Black Smut and Top Rot, the cosmopolitan ' pine-apple disease,' Cobb's 

 Gumming disease, and various so-called root diseases, most of which appear to 

 be due to basidiomycetous fungi. In what follows an attempt is made to 

 collate some of the more important points. 



Leaf Diseases. The leaf diseases of the cane are numerous and 

 wide-spread, but none are very dangerous ; they have been chiefly studied in 

 Java and more lately by Butler in India ; comparatively little attention has 

 been paid to them elsewhere. 



1 . Djamoer oepas. Large brown patches occur on the leaf and sheath, 

 caused by a silvery mycelium found on the surface, the haustoria of which 

 penetrate into the leaf, especially on the underside, and on the interior of the 

 sheath. Later, small bodies (sclerotia), first white, then yellow, and finally 

 brown, are observed on the dead portions of the leaf ; these spots are the size 

 of a grain of mustard; the leaves attacked soon wither and die, but the 

 damage is unimportant. 



2. Yellow Spot Disease. Cercospora kopkei. Krtiger. This disease 

 occurs as dirty yellow spots, often meeting to form one irregular blotch, 



the centre of which becomes red. A 

 brown mycelium is found on the leaf, 

 the branches of which, sometimes isolated, 

 sometimes united in bundles, carry colour- 

 less spores ; the appearance of the under- 

 side of the leaf is as if covered with 



* 270 



YIG. 60. a white dust. The damage is not great. 



The technical description of this fungus is : Cercospora kopkei. Maculis 

 amphigenus, sinuosis confluentibus purpureo brunneis infra palidoribus, margine 

 concolori ; hyphis plerumque hypophyllis fasicudatis, septatis apice noduhsis, 

 denticulatisque fumoso bruneis 40 50 X 7 conidiis fusoideis suberectis 20 50 

 x5 8wiedie 40x6 utrinque obtusiaculis 3 - 4 septatis non constrictis passum 

 guttulates subhyalinis. Various forms of the spores of this disease are shown 



in Fig. 60. 



* See note in Appendix. 



138 



