14 BULLETIN" 829, U. S. DEPARTMENT OF AGRICULTURE. 



Iii Cuba all varieties that are exposed seem to become infected, 

 but since the disease has not become rampant nor spread over any 

 considerable area no opportunity to observe the reaction of all the 

 varieties grown there is to be had. Practically all of the seedlings 

 originated in the Harvard Experiment Station near Cienfuegos were 

 affected, as well as the imported Java 228, L 511, and the native 

 Crystalina at Santiago de las Vegas. 



Practically all varieties are attacked in the Hawaiian Islands, and 

 extensive damage is done-. 



The common varieties in Louisiana have proved susceptible to 

 mosaic disease. Louisiana Purple, Louisiana Striped, D 74, D 95, 

 L 511, L 218, L 219, L 226, L 231, L 253, and hundreds of seedlings 

 being tested at the Louisiana Sugar Experiment Station all fall prey 

 to the" ravages of this disease. 



IMMUNE VARIETIES. 



Fortunately a few varieties of sugar cane have been discovered 

 which appear to be entirely immune. Most of them are of the 

 slender North India type, generally known as Japanese canes. The 

 Kavangire, a variety which, because of its prolific stooling, yields a 

 very large tonnage and is much esteemed in Argentina for making 

 sugar has never been observed to be diseased, although it has been 

 exposed to infection for four years in the worst infested regions of 

 Porto Rico. 1 It is a rather long season cane, however, and for this 

 reason is probably not suited to Louisiana conditions. Another Jap- 

 anese cane, Cayana 10, which is becoming prominent in the sirup 

 sections of Georgia and Florida, is also immune. This variety has 

 already met with considerable favor on the part of cane growers in 

 Georgia. All the o'ther Japanese varieties observed, including many 

 imported by the Office of Foreign Seed and Plant Introduction of 

 the Bureau of Plant Industry, have been found to be uniformly free 

 from this disease. 



Among the broad-leaved thicker stalked varieties several kinds 

 have been found that appear to be immune, but our evidence of their 

 immunity is not so complete as is the case with the Japanese varieties. 

 Louisiana seedlings 1646, 1606, 1674, and 1797, growing in the 

 variety test plats at Audubon Park, New Orleans, this year appeared 

 to be immune. No individuals of these varieties were diseased, 

 although they were surrounded by other varieties, the individuals 

 of which averaged 97 per cent diseased. 



i Townseud, C. O. An immune variety of cane. (Abstract of an article by F. S. Earle.) In Science, 

 n. s., v. 49, no. 1272, p. 470-472. 1919. 



