82 BULLETIX 351, U. S. DEPARTMENT OF AGRICULTURE. 



power outfit was used as in applying the cottonseed-oil sprays. The 

 oil was emulsified in the same way as kerosene in making kerosene 

 emulsion. This oil at 20 per cent gave an efficiency of from 93 to 

 100 per cent, but the injury to the trees was severe. It did far less 

 injury, however, than any other of the oils used at this strength. 

 This experiment shows that raw linseed oil was a promising oil and 

 that it should be used at a much decreased strength. 



Experiment 2 was performed on March 19, 1913, by spraying a 

 vigorous 2-year-old tree at Washington, D. C, with a 10 per cent 

 emulsion of raw linseed oil. This spray was applied very thor- 

 oughly with a hand sprayer at the time the buds were swelling. 

 Every scale upon this tree was killed and there was no spray injury. 

 The experiment shows that it is feasible to apply a 10 per cent emul- 

 sion to 2-year-old trees in the spring without injury. 



Experiment 3 demonstrated that a 5 per cent emulsion of raw 

 linseed oil will destroy more than 80 per cent of the scales upon 

 12-year-old trees, provided the application is made in the spring 

 before the buds open. In experiment 4 the formula used differs 

 from the one used in No. 3 in that gasoline was substituted for one- 

 half of the oil. The scale count gives nearly the same efficiency for 

 this experiment as for the preceding one. This experiment shows 

 clearly that gasoline increases the efficiency of the spray. Experi- 

 ment 5 was made by spraying 200 moderately vigorous 12-year-old 

 peach trees at Midvale, Pa.. Xovember 5, 1913, at which date the 

 trees had just finished shedding then* leaves. An emulsion con- 

 taining 5 per cent raw linseed oil and 3 per cent gasoline was applied 

 with a power sprayer, furnishing 175 to 200 pounds pressure, and 

 equipped with angle nozzles having apertures of one-sixteenth inch. 

 The efficiency upon well-sprayed branches was 100 per cent and there 

 was no spray injury. 



Experiments 4 and 5 show that an emulsion containing 5 per cent 

 raw linseed oil and 3 per cent gasoline will effectively control the 

 terrapin scale without injury to the trees. While experiment 5 

 shows that linseed oil gives good results in the fall, the author recom- 

 mends that this oil be applied in the spring just before the buds open. 



Cost of Lixseed Oil. 



At the date of writing this paragraph linseed oil sold in Wash- 

 ington, D. C, for 50 cents per gallon in barrel lots, and gasoline at 

 13 cents per gallon. The cost of this spray, exclusive of the labor of 

 making it, would be about 3 cents per gallon. 



5 gallons raw linseed oil, at 50 cents $2. 50 



3 gallons gasoline, at 13 cents 39 



2 pounds laundry soap, at 5 cents 10 



92 gallons water 



100 gallons 2. 99 



