116 TRINIDAD AND TOBAGO BULLETIN. [XIX. 3. 



Tlie last inspection of disease 1 localities in the Naparinjas, in December, 

 1920, resulted in only 550 diseased stools being found of which 380 were 

 on one estate. 



In October 1920 the Legislative Council voted .£500 for comijensation 

 for small farmers for caue stools destroyed. 



Over 40,000 stools were dug up and destroyed in the St. Augustine 

 and St. Joseph districts between September and December, but it was 

 then realised that much wider measures were necessary if there was to 

 be any hope of extermination. 



A. new campaign was then planned for the dry season of 1921 

 {Council Paper No. 23 of 1921) and the Legislative Council hks voted 

 the sum of j6o,000 for this purpose. 



Effect on Cxhk Plant. 



The most obvious symptom of the Mosaic disease is the irregular 

 fading of the green colour of the leaves, but some care and experience 

 is necessary to separate it from somewhat similar markings on leaves. 

 The following critical points should be noted : — 



1. The pale markings on the leaves in Mosaic disease are always 

 more or less elongated in the direction of the length of the leaf. 



Several varieties (particularly D. 1753) have normally, or abnormally, 

 small almost square or rectangular pale areas on the leaves, the cause 

 of which. is at present unknown. 



(2.) The pale areas in Mosaic disease are jiale green to almost white. 

 They are, except occasionally on older leaves (see below), the green of the 

 healthy canes diluted but are not more yellowish or brownish as is the 

 case of most other leaf spots. 



(8.) Mosaic is always more distinct in jilants that are otherwise 

 healthy. If the cane is pale from drought or bad soil, the pale areas do 

 not show so distinctly. 



It follows that manuring, especially with nitrogen supplied artificially, 

 so far from making any reduction in the disease actually makes it more 

 distinct bj' emphasising the difference between the decolourised areas 

 which remain pale, and the healthy areas which darken under this 

 treatment. 



(4.) Mosaic is always present more distinctly on the younger just 

 unrolled leaves than on the older outer leaves. 



It has been said that a leaf once open and healthy ca,nnot develop 

 the disease. Without admitting the truth of this statement, it is a 

 fact that the outer leaves of a cane may be healthy and the inner 

 diseased but never the reverse. 



Thus in cases of doubt in determination of the disease the inner 

 leaves should alwaj-s be examined. 



Quite contrary to the condition found in most varieties, and also 

 to several printed statements that the mosaic diseased leaf never 

 becomes brown, we find that in a few varieties the older infected leave* 

 become finely mottled with yellowish and reddish brown specks which 

 gradually increase in number until the death of the leaf. 



