2 BULLETIN 829, U. S. DEPARTMENT OF AGRICULTURE. 



of the interior throughout these regions. Its progress eastward was 

 slower, but at the present time more than three-fourths of the cane 

 fields of the island are invaded. 



During the last 12 months, methods of control have been put 

 into operation which have undoubtedly aided in checking the spread 

 of the disease into new territory. It has appeared sporadically at a 

 few points in the eastern fourth of the island, but the planters, 

 thoroughly aroused and alert, have not permitted it to spread there 

 as it has in the west. It has become the. practice to inspect the 

 fields regularly and eradicate diseased individual plants as they 

 appear, thus removing the source of infectious material. This 

 method has been successful where only a small percentage of the 

 plants are infected. In the west, where 75 to 100 per cent of the 

 plants in commercial fields are diseased, this method naturally can 

 not be recommended. The average reduction in output of sugar 

 for 10 mills in the worst infected area has been nearly 40 per cent, 

 notwithstanding an increased acreage in cane, while the average 

 output for 10 mills in the disease-free area shows a slight gain for 

 the same period. These figures are approximate, but they indicate 

 clearly the gravity of the situation. 



The disease is not new, but was recognized as an undesirable 

 condition in sugar cane as early as 1890 in Java, where it is called 

 gele strepenziekte, "yellow stripe." 1 Owing to the failure of Dutch 

 investigators to secure infection by artificial inoculation, they did 

 not regard the disease as infectious, but rather as frequently recur- 

 ring bud variations. This view was undoubtedly due to the fact 

 that it had for years been present, but unnoticed and unrecorded as 

 a specific disease, so that during this long period unconscious selec- 

 tion had eliminated all but the more or less resistant but not immune 

 varieties of cane. Thus, where the disease had become endemic it 

 would be especially injurious only to varieties imported from coun- 

 tries where the disease did not exist. It would be difficult to carry 

 on successful infection experiments where the disease is as prevalent 

 as it is in Java. 



Dutch investigators reported the presence of yellow stripe in 

 Egypt in 1909 on cane imported from Java and in the Hawaiian 

 Islands in 1910. In the latter territory nearly all cane regions have 

 become infested, and careful experiments have shown that where all 

 plants in a field are attacked, according to Table I, it causes a reduc- 

 tion in yield of sugar of 5 to 40 per cent, depending upon the variety 

 of cane. 



i Wilbrink, G.,;and Ledeboer, F. By drage tot de kennis der gele strepenziekte. Meded. Proefstat. Java- 

 Suikerindus., No. 39,2, p. 443-495, 5 pi. (4 col.), 1910. 



