378 Tobacco Growing for Insecticidal Purposes, [aug., 



TOBACCO GROWING FOR INSECTICIDAL 

 PURPOSES. 



G. H. Garrad. 



Assistant Botanist and Lecturer in Tropical Agriculture, 

 South- Eastern Agricultural College, Wye. 



Nicotine, the active principle of tobacco, has long been 

 known amongst fruit-growers as a very efficient insecticide. 

 It is, in fact, one of the most effective general insecticides we 

 have. Its effects are more lasting than those of any other 

 wash, especially if a small amount of soft soap is mixed with 

 it, and it does no harm to the foliage or to delicate blossoms. 

 Its penetrating power enables it to reach the inner surface of 

 curled up leaves, and when desired it can be mixed with a 

 sulphur wash for a combined attack on aphis, caterpillars, and 

 mildews. 



The price at which nicotine is sold on the market, however, 

 makes it too expensive for use for ordinary commercial pur- 

 poses. With nicotine (96 per cent, pure) at 155. per lb., and 

 using 1 1-5 oz. nicotine in 10 gallons of water, the cost of 

 the wash works out at nearly ijd. per gallon. Professor 

 Theobald considers 1 oz. nicotine per 10 gallons water quite 

 sufficient if a small quantity (5 oz.) of soft soap is added. 

 This reduces the cost to about id. per gallon, but even this 

 price is much too high for general purposes. 



To test the possibility of growing the tobacco merely for 

 insecticidal purposes experiments have been carried out 

 during the past year at the South Eastern Agricultural 

 College. 



In this connection the Excise Regulations respecting the 

 growing of smoking tobacco in this country are of primary 

 importance, but it must be remembered that for ^nicotine 

 extraction the variety grown would probably be a snuff 

 variety, unsuitable for smoking on account of its pungent 

 character, and rendered still more so by- the special treatment 

 it would receive to increase its nicotine content. The fruit- 

 grower, moreover, when growing his own insecticide, would 

 not cure the leaves at all, so that the tobacco would never be 

 in a fit state for smoking, and lastly, to eliminate all possi- 

 bility of the home-grown tobacco being used for illicit 



