88 BACTERIA IN RELATION TO PLANT DISEASES. 



ation of the cultivation of cane ; in this period effort has been made to obtain the largest yield and sell 

 the greatest possible amount of cane, reserving for seed-cane only that which the inspectors have 

 refused, and that which has no value. Here is the explanation of the unexpected appearance of the 

 Polvillo and its enormous spread. This explains also why the cane planters observed that the ratoon- 

 cane, when the product of healthy seed-cane, was but slightly or not at all diseased, while the plant- 

 cane the product of diseased cuttings or canes was usually diseased. 



To-day all the canes, cuttings and plants, are equally affected, because now they all have the 

 same vicious origin. 



It must be left an open question whether this disease of Argentina is or is not Cobb's 

 disease of sugar-cane. Of course, if we accept Spegazzini's statements respecting his Bacillus 

 sacchari at their face value, it is likely to be something else, but on the other hand, making 

 some allowance for unfamiliarity with this type of disease and considering the difficulty 

 Spegazzini mentions having encountered in making isolations, together with the general 

 character of the signs described, namely, spread from cuttings, chlorosis, striping and dry- 

 ing out of the leaves, death of the terminal bud with the production of yellow bacterial slime 

 and red stain, gumming of the dead sheaths about the terminal bud, which becomes distorted, 

 marked red stain in the nodes and in the vascular bundles, old canes sound externally but 

 diseased within, it seems probable that this disease should be referred to Bacterium vascu- 

 lar um. 



In the spring of 1910 the writer received an agar-streak culture from Prof. Spegazzini, 

 marked as his B. sacchari. This was a whitish layer containing quite a good many roundish, 

 somewhat yellowish, small colonies in its substance which appeared to be another schizomy- 

 cete. An attempt was made to cultivate both organisms, but only the white one grew. 

 No cane was available for inoculation at that time. When cane plants were finally avail- 

 able in the fall inoculations were made, but with entirely negative results. 



The writer had promise of diseased canes from Tucuman in 1 9 1 2 , but none were received. 



LITERATURE. 



1895. Spegazzini, Carlos. La Gangrena Humeda 6 1896. Spegazzini, Carlos. Hongos de la Cana de 



Azucar. Revista de la Facultad de Agro- 

 nomia y Veterinaria, No. xix, Ano n. La 

 Plata, July 31, 1896, pp. 238-239. 



Polvillo de la Cana de Azucar en Tucuman. 

 La Plata, June 15, 1895, 29 pp. 



