2/0 TOBACCO 



Whilst insecticides, both internal and contact poisons, 

 were totally unknown in Deli about ten years ago, they 

 are now very generally used. 



Schweinfurt Green, imported by the Deli Testing 

 Station in 1906, is now used annually in quantities of 

 many thousands of kilograms (in 1913, 30,000 kilograms). 

 The seed-beds, as well as the recently planted tobacco, 

 is treated with this. In the case of the former the 

 Schweinfurt Green, at a strength of i part per 1,000, 

 is sprayed by means of a pump fitted with a powerful 

 mixer, at the same time as the bouillie bordelaise. For 

 tobacco in the field the insecticide at a strength of i per 

 cent, is thoroughly mixed with tapioca flour, sifted dust, 

 or a mixture of both; of this mixture, a small quantity is 

 strewn into the hearts of the young plants from a pepper- 

 box on the spot where the female of Heliothis prefers to 

 lay her eggs, 



A disadvantage O'f Schweinfurt Green is that, under 

 certain circumstances, it produces a blight on the plants 

 treated with it. Although such injury is not usually 

 very serious, another insecticide free from this risk 

 was imported, viz., arsenate of lead. As its action, 

 however, is less powerful and less quickly destructive, 

 it has to be used in a much more concentrated 

 form (up to 4 per cent.), which renders it much 

 more 'expensive than Schweinfurt Green. Hence its 

 application, although blight is absolutely excluded, is 

 less frequent than that of the first-named insecticide (in 

 I 9 I 3 ? 9,ooo kilograms). 



Against the green-fly pest, which sometimes occurs in 

 a very violent form, the following mixture has been 

 recommended with great success : 



450 c.c. of 10 per cent, tobacco extract. 



150 gr. green soap. 



150 c.c. alcohol. 



150 gr. soda. 



200 c.c. water. 



This quantity must be diluted with water to make up 

 15 litres. 

 Those estates which usually suffer from green-fly 



