May 16, 1919] 



SCIENCE 



471 



be identical with the yellow stripe disease pre- 

 valent in Java and some other cane countries. 

 At the request of the Porto Rican authorities 

 the U. S. Department of Agriculture entered 

 into cooperation with the insular and federal 

 stations on the island, and Professor F. S. 

 Earle, of the Office of Sugar-Plant Investi- 

 gations, Bureau of Plant Industry, was de- 

 tailed to take up the cooperative work in Porto 

 Rico in Augiist, 1918. 



Among other lines of investigation Pro- 

 fessor Earle studied very closely the sugar 

 cane varieties growing in Porto Rico. He 

 noted that among about twenty varieties grow- 

 ing at the federal station at Mayaguez there 

 was one Japanese variety (Kavangire) showed 

 no sign of the mottling disease, while all the 

 other varieties there were more or less seri- 

 ously affected. In order to carry this study 

 further Professor Earle, throvigh the kind co- 

 operation of Russell & Co., inaugurated an ex- 

 periment with ninety varieties of cane on 

 their Santa Rita Estate. These varieties were 

 planted and grown under the jiersonal super- 

 vision of Russell & Co.'s cane planting expert, 

 Mr. H. Bourne of Barbados. Single rows of 

 cane were planted of the varieties to be tested, 

 and every third row was planted with diseased 

 seed of the Rayada variety (ribbon cane). In 

 this way each variety was uniformly and com- 

 pletely exposed to the infection. 



The first planting of the ninety varieties was 

 made on October 1, 1918. Two and one half 

 months later Mr. Bourne reported that all of 

 the varieties except the Kavangire showed the 

 mottling disease, the infection rimning from 

 9 per cent, to 96 per cent. This variety has 

 remained free from disease to date, March, 

 1919, and shows every indication thus far of 

 being immune to the mottling disease. 



On January 29 of this year Professor Earle 

 made a careful study of the experiment and 

 foimd about half of the other varieties. in this 

 experiment showing an infection of fully 100 

 per cent., and in only two cases was it as low 

 as 50 per cent. The degree of infection, how- 

 ever, was decidedly marked in different va- 

 rieties, a few of them showing the disease but 

 slightly, indicating that they are resistant 



though not immune, with the exception of the 

 one variety Kavangire which appears to be 

 entirely immune. In three or four of the 

 least infected kinds close observation is nec- 

 essary to detect the disease, the only evidence 

 being very faint " watered silk " discolorations. 

 Professor Earle has observed the Kavangire 

 fully matured on the federal station at 

 Mayaguez and in other localities, and in all 

 of the localities in Porto Rico where it is 

 growing it is entirely free from the mottling 

 disease whether the plants are young shoots 

 or mature canes. 



The Kavangire cane is tall-growing and 

 very slender, while the Porto Rican planter 

 prefers a thick cane, because it appears to be 

 a better yielder and is handled at less ex- 

 pense. However, the yield of the Kavangire 

 under some conditions at least compares favor- 

 ably with other varieties, and very greatly ex- 

 ceeding them in some cases. Director May 

 reports a yield at the rate of 70 tons per acre 

 on the Mayaguez plot. No analyses of the 

 Kavangire variety, as grown in Porto Rico, 

 are available, but according to some reports 

 from other countries where it is grown it 

 varies from 14.38 per cent, sucrose to 16.85 

 per cent, sucrose, while its purity coefficient 

 varies from 84.6 to 89.67. 



The Kavangire cane was imported into 

 Porto Rico from the Argentine a few years 

 ago by Mr. May, director of the Federal Ex- 

 periment Station at Mayaguez. In Argentine 

 it has been planted quite largely on a com- 

 . mercial scale indicating that it is satisfactory 

 from the standpoint of sugar production. It 

 requires a long season for maturity, and for 

 this reason has not been recommended for 

 general planting in Argentine. The sugar per 

 acre is the crucial test, and in this respect the 

 Kavangire generally stands near the top, so 

 far as available records indicate. 



After reviewing the available literature in 

 regard to Kavangire Professor Earle raises 

 the practical question as to whether or not 

 Kavangire can be successfully used for gen- 

 eral planting in Porto Rico. If it can and it 

 retains its immune characteristic the question 

 of combating the mottling disease is solved. 



