SECTION X. — METHODS OF CONTROL. 141 



Finally we have the fact that in the burning of the trash a large 

 amount of vegetable matter is destroyed which would otherwise decay 

 to Iiumus in the soil and so improve its pliysical conditions. On soils 

 rich in humus and well aarated this loss would not b ; so important, but 

 in Trinidad there are few soils of this nature and one of the prime needs 

 of the blighted areas is, as has already been shown, a better physical 

 condition of the soil. 



From these considerations it is reasonable to conclude that, for the 



■ control of bhght, the less burning of trash that is carried out the better 

 will be the results, particularly in the future when tlie accumulated 

 humus begins to have effect. 



Spraying. Gough (1910 B. p. 176) suggests spraying the bases of 

 the cane stems with tobacco juice just after the first flight of adults to 

 • destroy the eggs. I dipped a number of pieces of trash cont lining eggs 



■ 3-5 days old, in a solution of 1 in 240 Black Leaf 40 (Nicotine) for three 

 minutes, the pieces being subsequently dried on blotting paper. Several 



■ eggs survived this treatment and hatched within the next few weeks. 



The results of experiments with Mr. Glasgow's pre[)aration contain- 

 ing corrosive sublimate will be summarised later in connection with the 

 destruction of the nymph (p. 142). 



Destruction of thk Nymph. 



Weeding. The remarks already made in dealing with the destruc- 

 tion* of the eggs apply here also. 



In dealing with abandoned lands which are believed to be a source 

 of danger as breeding places, it is important that they should be 

 brushed (cut over) while the froghopper is in the egg or young nymph 

 stage, as if the adults have begun to emerge they wiil have all the more 

 inducement to spread into the surrounding fields. Abandoned fields so 

 brushed should be put into some form of cultivation or ploughed up as 

 soon as possible. 



Flooding. In British Guiana, where the greater part of the sugar 

 lands are below the level of the irrigation canals, fields are sometimes 

 flooded in order to destroy the nymphs (Williams 1918 B. p. 165). This 

 method can never be adopted in Trinidad as there are nowhere the 

 facilities for rapid drainage that is an essential part of such a nirithod. 



Use of Chemicals and Sprays. A. large number of chemicals have 

 been at times experimented with and so far none has proved successful. 

 Gough (1911 C. p. 26) discusses the use of quick lime, lime wash, lime 

 sulphur, kerosene emulsion, kerosene lysol emulsion, rosin wash, cyanide 

 of potassium, and copper sulphate. His conclusions are that the only 

 ones worthy of further trial are the kerosene emulsion and the kerosene- 

 . lysol emulsion. 



I have reports from planters of experiments witli Cooper's cattle dip, 

 "milk-oil," Bordeaux mixture, salt and lime, carbon bi-sulphide, tobacco 

 -dust and nicotine solution. All of these were found of no practical 

 value. 



The frothy covering of the nymph protects it from most sprays 

 unless they are of unusual strength, and expei'imjnts in which the 

 nymphs are removed from their froth are misleading unless followed by 

 others with the nymphs in their natural state. 



