FUNGOUS DISEASES IN SHIPMENTS OF SUGAR CANE. 



13 



The organisms causing root -rot are wound parasites, usually living 

 a saprophytic life in the soil. Wlien the cane is weakened from any 

 cause, such as drought, poor cultivation, etc., the fungus can make 

 an entrance into the roots. The root fii'st shows a reddening of the 

 surface, followed by a brown discoloration, and finally a slow disin- 

 tegration. Plants so affected are weak and dwarfed and easily blown 

 over by the wind or uprooted. The lower leaf sheaths are frequently 

 enveloped hi a wliite weft of fungous threads which cement them tight 

 to the stalk. The disease 

 is nmch more prevalent 

 on ratoon crops than on 

 planted cane, a;S it lives 

 and grows on the stubble 

 year after year. On 

 planted cane the fungus 

 envelops the stalk and 

 soon smothers the buds, 

 thus preventing germi- 

 nation and resulting in a 

 poor stand. 



Control. — Dr. Fulton 

 suggests the following 

 preventive measures : ( 1 ) 

 Careful cultivation, (2) 

 selection and disinfection 

 of seed cane, (3) plant- 

 ing of resistant varieties, 

 (4) destruction of in- 

 fected trash, and (5) ro- 

 tation. So far as known, no other crop is affected by root disease 

 except .sweet potatoes. ^ This has been reported from Barbados, 

 St. Lucia, and Antigua, of the West Indies. 



RIND DISEASE. 



Rind disease {Trichosphaeria sacchari Massee) was once held to be 

 the cause of a great amount of damage in the West Indies and else- 

 where. More recently the rind fungus has been considered by various 

 investigators to be a secondary factor appearing only after the cane 

 has been weakened from some cause or following some parasite such 

 as the red-rot organism. The fungus causes little damage other 

 than hastening the complete destruction of already diseased cane. 

 (See fig. 7.) 



I South, F. W. Disease of sweet potatoes. West Indian Bulletin, v. 11, No. 2, p. 82, 1911. 

 [Cir. 12G] 



Fig. ".—Rind disease of sugar cane, showing long, black threads 

 of spores at "c." (After Cobb.) 



