154 CHAPTER IX 



CANE DISEASES. 



The sugar cane, in common with other cultivated plants, is subject to a 

 number of diseases. The great majority of these are known to be due to 

 certain specific fungi, but in one case, the gumming disease, the causal 

 organism is a bacillus. In a number of cases the causal organism is specific 

 to the cane, that is to say it has been observed as parasitic on the cane and 

 on no other plant. In other cases, as in the pineapple disease and the root 

 disease, other plants may act as hosts. 



An interesting point in regard to cane diseases is the very wide distri- 

 bution of one and the same organism, as instanced by the red rot of the stem 

 (Colletotrichum falcatnm) known to occur in Java, British India, the West 

 Indies, Louisiana and Hawaii, and in the gumming disease known to occur 

 in Brazil, Argentina, Madeira, Mauritius and Australia. 



This wide distribution can best be attributed to the uncontrolled importa- 

 tion which has taken place in past times. In the case of the gumming 

 disease, certain facts on record are suggestive, though not positive. This 

 disease was first described by Dranert 58 in 1869 as prevalent in Brazil. 

 At this very time importations of Brazilian canes were made to Mauritius, 

 and from Mauritius there have been frequent exportations to Australia. 

 It is in these three widely separated localities that gumming is known as a 

 dangerous disease. 



On the other hand it is sometimes possible to specify the period of in- 

 fection, as instanced by the introduction of Iliau to Louisiana 59 along with 

 canes sent from Hawaii, and of the Australian leaf-splitting disease to For- 

 mosa. 60 But perhaps the most suggestive illustration is that connected 

 with the outbreak of the yellow stripe disease in Porto Rico in 1916. Pre- 

 viously yellow stripe had been known as a pathological condition in Java 

 and in Hawaii, but had not been recognised as an infectious disease. About 

 1910 certain approved Java seedlings were imported into Egypt, thence they 

 went to Argentina, and from there they were brought to Porto Rico in 1914. 

 In no one of these localities had yellow stripe been recorded before, but in 

 each, shortly after the introduction, the disease was recognised, and in 1916 

 it assumed a dangerous epidemic form in Porto Rico, becoming also known 

 there as the Mosaic or Mottling disease. 



The history of the sugar cane is associated with a number of epidemics 

 of disease. The earliest of which any record exists is that which occurred 

 in Mauritius and Reunion in the years 1848-5 1, 61 and which forms one of 

 the links made use of by Darwin in building up his theory. The cane 

 affected was the original stock introduced by Bougainville from Otaheite^ 

 and the disease was characterized by a " corkscrewing " of the top and a 

 yellowing off. At the time it was attributed to degenerescence, and it was 

 observed that the degenerescence had been noticeable for fifteen years before 

 the fulminant outbreak. 



Second in sequence is the epidemic of gumming, which appeared in 

 Brazil as early as 1857, an d was very prevalent in 1865 ; the variety mainly 

 affected was the Cayenne or Otaheite cane. 



Gumming was also responsible for an epidemic in Madeira in 1885, and 

 again appeared in a fulminant form in Mauritius in the 'nineties. Here 

 again the cane most affected was the Louzier, which probably represents a 

 second establishment of the Otaheite stock. Third in chronological order 

 is the epidemic which became serious in Porto Rico in 1872, causing the 



