I04 PLANT DISEASES 



shoots, dead leaf bases, etc., but more especially through 

 the wounds made by the moth-borer {Diatraea saccharalis, 

 Fabr.), or the shot-borer (Xyleborus perforans. Wall.). 

 When the mycelium attacks the living tissues it usually 

 first follows the vascular bundles, which assume a bright 

 red colour, characteristic of the incipient stage of the 

 disease. Eventually two conidial forms of fruit are 

 produced, microconidia and macroconidia, which burst 

 through the siliceous cuticle of the cane, and form sooty 

 streaks on the surface. Finally, the ascigerous form of 

 fruit is developed only on very old and much decayed 

 canes. The disease has been most severe in the West 

 Indies, but has also been recorded from Mauritius, India, 

 Java, and Queensland. 



Prkventive Means. — When the mycelium once gains 

 an entrance to the tissues of a cane, it spreads through- 

 out its entire length. Diseased canes yield little or no 

 sugar, and consequently were used for propagation, being 

 cut into pieces about one foot long. Diseased canes 

 were also left lying about on the ground, affording every 

 facility for the spread of the disease. Now that the fields 

 are kept clean, and only healthy canes used for propaga- 

 tion, the terrific wave of disease, which for a time 

 paralysed the sugar industry in Barbados and other West 

 Indian islands, is disappearing. 



Massee, Ann. Bot., vol. vii. i pi. (1893). 

 Went, Ann. Bot., vol. x. p. 583, pi. 26. 



