1920.\ MOSAIC DISEASE OF SUGAR CANE. • 31 



It is estimated that for 1918 in Porto Rico the financial loss amounted 

 to $2,500,000, making with losses for 1916 and 1917, a to'.al of about, 

 1j3, 500,000. The decrease in crop results primarily from reduction in 

 tonnage. 



In Hawaii the reduction in yield in diseased canes varies from 

 5 to 40 per cent, in different varieties. 



In Louisiana the disease was only discovered in 1918 but evidence 

 shows that it was introduced into the Experimental plots of the Audubon 

 Park Sugar School some time- shortly before 1914, as since that date 

 " every point receiving seed (cuttings) from the station has become the 

 centre of a larger or smaller infected area." " At the present time 

 97 ner cent, of the plant canes at the station have the Mosaic Disease." 



Preliminary observations in Louisiana indicate a loss reaching at 

 least 12 per cent. 



No cure is known ; the only control methods being to destroy when 

 possible every diseased stool, never to take cuttings for planting from 

 diseased stools, to inspect at intervals all fields of young plant canes 

 suspected to be infected, and to uproot all stools showing signs of the 

 disease. 



OCCURRENCE IN TRINIDAD. 



Early in 1918 a plot of canes of the variety D. 3956 at the St. 

 Augustine Experiment Station, was noticed to have the leaves streaked 

 with pale yellowish green. A year later the same unusual appearance 

 was apparent, if anything more pronounced, but nothing similar was 

 noticed on the neighbouring beds. 



Towards the end of 1919 I pointed out the condition to i\Ir. W. Noweli, 

 Mycologist of the Imperial Department of Agriculture, who was in the 

 colony, and we discussed the possibility of its being the Mosaic Disease. 

 A little later a close search revealed the fact that many other varieties 

 were infected to a greater or less degree, and as a x^recaution no further 

 cuttings were sent out from the station. 



Specimens, dried and in formalin, were sent to Mr. M. A. Taylor, 

 Chief of the the Bureau of Plant Industry, United States Department 

 of Agriculture, who replied in March, 1920, as follows : — 



" Dr. E. W. Brandes, Pathologist in Sugar Plant Investigations, 

 whom I asked to examine this material, advises me that there can be no 

 question but that the dried and formalined specimens are affected by 

 Sugar Cane Mosaic. He would not make this diagnosis solely on the 

 dried material, but the leaves in formalin show the typical condition 

 induced by the disease. The importance of prompt and thorough action 

 with respect to its eradication, if it is not too firmly established, is 



considered by our pathologist-; to be very f.reat 



Dr. Brandes advises further that the cane varieties which you mention 



