178 TBINIDAD AND TOBAGO BULLETIN. [XIX. 4. 



Sugar-cane mosaic became generally known in consequence of a 

 severe epidemic which began to develop in Porto Rico about 1916. The 

 disease had previously existed for many years in several localities in the 

 East, especially in Java, where it was known as yellow stripe, and was 

 not regarded very seriously owing to the powers of resistance of the 

 local cane varieties. The disease is now known to occur in the Western 

 Hemisphere in Louisiana, Florida and adjoining States, in Jamaica, 

 Cuba, Santo Domingo, Porto Rico, Barbados, Trinidad and the /Argentine. 



The disease was first recognised in Trinidad in 1920, when it was 

 found to be abundantly distributed at the St. Augustine Experiment 

 Station and its neighbourhood, from the outskirts of Port-of-Spain to 

 Tunapuna. Many small centres of infection had also been established 

 in the island by cuttings sent out from St. Augustine. 



The first symptom of sugar-cane mosaic appears on the leaves in the 

 form of pale, more or less elongated spots or streaks, difficult to describe 

 but usually easy to recognise. A useful distinction from various 

 un-related types of spotting which occur is that in mosaic the youngest 

 leaves are always affected. Later symptoms appear on the stems, 

 consisting of discoloured or water-soaked patches or streaks which in the 

 more susceptible varieties become sunken and cracked, causing the 

 cane to dry out and lose greatly in weight. 



During prolonged dry weather no spread of the disease is noticeable, 

 but subsequent to the first month or two of the wet season fresh 

 infections occur with a frequency that varies greatly according to period 

 and locality. Transmission is believed to be due to an insect carrier, 

 not yet recognised. 



Cuttings from infected canes reproduce the disease and afford the 

 means of its extension over large areas and transmission over long 

 distances. 



With the exception of Uba no cane variety grown in Trinidad is 

 known to be immune from mosaic, but here as elsewhere there appear 

 to be somewhat wide differences in susceptibility to infection and in 

 resistance to the more serious effects of infestation. These effects 

 have not been allowed to develop to any great extent in Trinidad, but 

 there is evidence enough to show that in the less resistant varieties 

 they have a severity comparable with that reported from Porto Rico. 



The discovery of the disease in the island was followed by efforts on 

 the part of the Department of Agriculture to effect its eradication, and 

 these are being steadily pursued. Infested disti'icts are regularly 

 ins]:^pcted and in the case of small farmers compensation has been paid 

 for the stools destroyed and new plants supplied free. As sufficient time 

 has now been given for the education of the grower to recognise and 

 deal with the disease it is proposed that future work will consist of 

 inspection and where necessary the issue of orders under the Plant 

 Protection Ordinance. 



