210 



TRINIDAD AND T OB AGO BULLETIN, \XIX. 4. 



An attempt was also made during the crop season of 1920, to estimate 

 the loss sustained on canes attacked with mosaic disease; this may be 

 twofold : (1) loss of weight on the crop and (2; inferior quality of juice 

 from diseased canes. 



For carrying out these investigations, blocks of twenty stools each of 

 plant canes and first ratoons were marked off". Generally, the varieties 

 selected were those which appeared to be the most seriously aff'ected 

 with a view of obtaining sufficient material to ensure accurate results. 



After marking out the plots all the canes were cut and removed to a 

 convenient spot where they were sorted into healthy and diseased canes 

 and classified according to their approximate degree of ripeness. The 

 canes from each section were then counted and weighed separately. A 

 proportionate number of canes from each classification from the healthy 

 and diseased canes respectively was then sampled for analysis. The 

 lengths of ten healthy and diseased canes respectively were measured and 

 the canes weighed. 



The field results are given in Tables XVII to XIX and the analytical 

 results in Tables XX to XXII. 



The figures under the column loss per cent, indicate the loss that 

 would have occurred if all the canes had been diseased whereas those 

 under the column true loss show the actual loss sustained based on the 

 percentage of diseased and healthy stools found for each variety. 



Table XVII. — Loss due to Mosaic Disease. — Weight of Cane. 

 Plant Canes, Field 9.— 20 Stools. 



