12 



CIRCULAR NO. 126, BUREAU OF PLANT INDUSTRY. 



conditions, usually in the spring, these bodies produce the mycelium, 



which may penetrate those leaf sheaths with which it comes in contact. 



The disease flourishes during damp weather. 



Control— RemoY id and burning of the lower leaf sheaths and leaves 



are recommended. Infected cuttmgs should not be used for plantings. 



Kriiger states that if infected cut- 

 tings come up at all they seldom 

 ])r()ducc well-developed plants. 



ROOT DISEASE. 



Root disease is probably present 

 in all the sugar-cane regions of the 

 world. It is commonly caused by 

 one of the following fungi: Maras- 

 mius plicatus Wakker, M. sacchari 

 Wakker, or Ithyphallus coralloides 

 Cobb. Great losses have been sus- 

 tained from this trouble. Dr. Cobb ^ 

 estimated that in Hawaii failures 

 frequently amounted to 25 per cent 

 and in a few cases as high as 50 or 

 60 per cent, while a conservative 

 estimate was placed at 10 per cent 

 of the ratoon crop and a somewhat 

 smaller loss on the plant crops. 

 In Louisiana Prof. H. R. Fulton - 

 states: 



It is a usual thing to find the purple plant 

 cane affected to the extent of 5 to 8 per 

 cent of the stalks, and purple first-year stub- 

 ble, 12 to 18 per cent. In the case of D 74, 

 1 to 3 per cent and 4 to 8 per cent are usual 

 figures for the corresponding crops. Some 

 of the worst fields seen have been in purple 

 cane and have had 90 or 95 per cent of the 

 stalks infected. These figures are not to 

 h(> taken as representing in any way the 

 loss due to the root disease. Affected 

 canes, although usually small and light, 

 are by no means a total loss; and the fig- 

 ures do not take into account the gaps in 



stands and the reduction in number of canes per stool that make tip the large loss 



from root disease. 



Fig. 6.— Sclerolium disease of sugar cane, showing 

 darkened, sunken areas below the nodes. 



1 Cobb, N. A. Op. cit. 



2 Fulton, II. R. Root disease of sugar cane in Louisiana. Louisiana .Vgricultural E.xpenment Station, 



Bulletin 100, 21 p., 8 figs., 1908. 

 [Cir. 12G] 



