160 COMMON INSECT PESTS 



A mixture of this strength is known as the 5- 5— 50 formula. 



The quantity to be made at one time is a matter of conve- 

 nience, depending on the number of plants to be sprayed and 

 on the available vessels. 



Fiftv gallons is often a convenient quantity to make at a 

 time ; tor this, one 50-gallon barrel and two 25-gallon tubs 

 are required. The method of preparation is always the same 

 whatever the quantity of mixture required — 



(1) Wrap 5 lb. of copper sulphate in a piece of gunny 

 bag, powder it on a stone, tie up the piece of gunny and 

 suspend it by a string to a stick laid across the mouth of a 

 tub containing 25 gallons of water. In a short time the 

 copper sulphate will have dissolved. 



(2) Put 5 lb. of good quicklime in a tub, and sprinkle 

 about a quarter of a gallon of water on it. When the lime 

 begins to crack and crumble add more water a little at a time, 

 taking care that the lime does not become too dry. Keep on 

 adding water, a little at a time, till a thick creamy paste free 

 from lumps is formed. Add the requisite quantity of water 

 to make up to 25 gallons. Stir well. 



(3) While stirring vigorously, slowly pour the solution 

 of copper sulphate and the milk of lime together into the 

 large barrel. Keep stirring for two or three minutes. 



Properly prepared mixture is of a light sky blue colour. 



When using Bordeaux mixture during the monsoon, an 

 adhesive substance must be added to prevent the mixture 

 being washed off by the rain. An efficient adhesive may be 

 prepared from resin and washing soda. For the above 

 quantity of 50 gallons Bordeaux mixture put 2 lb. washing 

 soda in an earthenware pot containing 2 gallons of water and 

 bring to the boil. Add 4 lb. of powdered resin, a little at a 

 time. For the first half hour the liquid is liable to boil over, 

 so the fire should be a slow one, as the liquid becomes clear 

 the fire may be made to burn more brightly. The liquid 

 should be boiled altogether an hour. It becomes clear like 

 coffee decoction. While stirring vigorously slowly add the 

 resin-soda liquid to the Bordeaux mixture. 



Test.— Rub the blade of a knife in sand or earth till it is 

 polished, then dip in the mixture for a minute. If the blade 

 is unchanged the mixture is safe. But if the blade becomes 

 red, then more lime must be added, till the clean blade is not 

 stained when dipped afresh in the mixture. 



