82 



T BIN ID AD AND TOBAGO BULLETIN. [XVIIL 2. 



There is no Immune Variety. — It then becomes a question as to 

 relative powers of resistance. Do some varieties, even if damaged, suffer 

 less severely than others under similar conditions '? To this the answer 

 is more hopeful. 



In collecting evidence for this branch of the problem it is not enough 

 that fields of two varieties side by side should show a different extent of 

 damage. The canes may be of different age, the fields may have had 

 different treatment, the soil, which, in the Naparimas especially, changes 

 rapidly, may be different in two adjacent fields, or even in two parts 

 of the same field. 



Allowing for such conditions there is still distinct evidence tliat 

 some canes will survive when others are more severely damaged. 

 This difference is usually most strikingly seen in fields of one variety 

 which have been supplied with canes of a second variety. Several 

 examples of this will be found in the above notes. 



Thus Hill's Seedling No. 1 was standing out among other canes on a 

 Farmers plot at Inverness ; Fostei-'s seedling is not so good as D. 145 

 or D. 625 supplies at La Fortunee and Golconda respectively. D. 109 

 is twice recorded as better than B. 156 and again as better than B. 347 ; 

 D. [366 is more severely damaged than either D. 504 or B. 156 on 

 adjacent beds at St. Augustine, etc. 



Perha25s the most striking example of relative resistance to blight 

 was seen at Harmony Hall in 1917 where a field had been planted with 

 alternate beds of Uba and ]J. 347. The field was heavily infested with 

 Froghoppers, with the result that while the Uba was damaged 

 sufficiently badly to reduce the crop nearly 50 per cent., the B. 347 

 almost ceased to exist and the end of the field had the appearance of a 

 castellated wall. 



It must be remembered that these relative differences apply probably 

 only to the particular soil and climatic conditions under which the 

 observations were made. On other soils and with different rainfall the 

 difference might be reduced or even inverted. 



From a careful inspection of the above results and fi*om personal 

 experience in the field, it is probable that the two most I'esistant 

 varieties at present in cultivation are Bculilla a)id Uba. Unfortunately 

 neither of these canes are in particular favour in the factories, as both 

 are very hard with large fibre contents and except in heavy mills do not 

 give good juice yields. In addition neither are suitable for very heavy 

 soils. 



Uba cane is being increasingly used by the estates of the Usine 

 St. Madeleine, to grow on small patches of poor soil, along ridges and 

 elsewhere. 



^Yhere other canes do not floui-ish, and under such conditions it has 

 been found to give extremely satisfactory results. 



At the Experiment Station St. Augustine, and on some other estates, 

 are to be found a number of recently introduced varieties. Blight does 



