APHIDS INJURIOUS TO ORCHARD FRUITS. 



37 



to make nicotine sprays at home. Owing to the variation in nicotine 

 content of tobacco refuse, there is danger of having the spray too 

 Aveak on the one hand or stronger than necessary on the other. 



The following table, adapted from Bulletin 208 of the Virginia 

 Agricultural Experiment Station, illustrates the variation in nicotine 

 content of tobacco stems, refuse, and various kinds of tobacco, and 

 may serve as a guide to those planning to make decoctions from 

 tobacco refuse at home: 



Formula for making nicotine extracts. 



Kind of tobacco. 



Light stems 



do 



Sweepings , 



N. L. Orinoco... 



Olive 



Light 



Sweepings , 



Smoker 



Wrapper 



Cutter 



Dark 



N. L. Orinoco 



Medium smoker . 

 Common smoker. 



Richmond, Va 



Danville, Va 



do 



Appomattox, Va. . . 



Powhatan, Va 



Danville, Va 



Louisville, Ky 



Chatham, Va 



do 



do 



Appomattox, Va 



Bowling Green, Va. 



Chatham, Va 



do 



Per cent. 

 0.4S1 

 .609 

 . SS4 

 5. 535 

 3.367 

 2.984 

 .7.53 

 2. 306 

 3.05 

 3.466 

 2.835 

 5.629 

 3.766 

 2.47 



Number of pounds 

 per 100 gallons 

 neeesary to 

 make solutions 

 containing differ- 

 ent percentages of 

 nicotine. 



0.06 p. CI. 

 145 



no 



74 

 121 

 19i 

 22" 

 91 

 28i 

 21.', 

 19 

 23] 

 111 

 171 



Tobacco decoctions can be made conveniently in a lime-sulphur 

 cooking plant, being heated either by steam or by fire under open 

 kettles. The proper quantities of refuse tobacco and water should 

 be placed in the container and the water heated to about the boiling 

 point, after which it should be allowed to cool. Where steam is 

 used a slight increase in water will occur, and a slight decrease where 

 fire is used, although the variation usually will be negligible. Heat- 

 ing the decoction by either method may result in a slight loss of 

 nicotine, especially if the w^ater is allowed actually to boil. 



Another method is simply to soak the tobacco refuse in water for 

 24 hours with frequent stirrings, using a barrel, vat, or other suit- 

 able container. This method removes about the same amount of 

 nicotine (70 to 80 per cent) as does the heating process. After the 

 heating or soaking has been completed the decoction should be 

 strained to remove fragments of leaves, etc., and if pressure can be 

 applied to the mass of refuse some additional liquid will be ob- 

 tained. 



Reference to the table will indicate the amounts of several types 

 of refuse which should be used to produce an effective aphid spray. 

 Probably in most cases the refuse at hand can be considered as be- 

 longing to some one of the types indicated in the table. Observa- 



