58 FRUIT TREES AND THEIR ENEMIES 



emulsion may do, if used too strong, or if made 

 improperly. 



The strength of solution which has been found very 

 effective is one made by soaking 2 lbs. of strong 

 tobacco in 10 gallons of water. For use on a practical 

 scale, however, tobacco which has paid duty is too 

 expensive, and what is known as denatured tobacco 

 must be used. This is sold in the form of a powder, 

 known as hop-powder, and contains about 70 per cent, 

 of tobacco or snuff, mixed with sulphur, assafcetida 

 and sago flour. It may be bought for 20s. to 30^". the 

 hundredweight. The tobacco used in making it, 

 however, varies considerably in strength, and it is well 

 to take 4 lbs. of it to every 10 gallons of water for 

 making the decoction. 



It is better still to use nicotine instead of tobacco. 

 This may be bought of about 96 per cent, purity for 

 \2s. the lb., or weaker solutions may be obtained, 

 specially prepared of guaranteed strength by dealers 

 in insecticides. In either case the preparations should 

 be diluted for use so as to contain 0075 per cent, 

 of nicotine, equivalent to lith ozs. to 10 gallons. 

 Growers should be very careful to obtain a guarantee 

 as to the strength of the solution purchased, as there 

 are preparations of so-called commercial nicotine on 

 the market, which are sold at a low price, but which 

 contain only 2 to 3 per cent, of the substance. 



The spraying of trees with nicotine solution during 

 flowering does not interfere with the working of bees, 

 and these seem to be quite uninjured by the poison. 



Nicotine solution can be used in conjunction with 

 soap, and also with any paraffin emulsion, or lead 



