8 HOW TO CONTROL THE PEAR THRIPS. 



thrips present or even a large percentage of them, there was consid- 

 erable oil injury to the buds. It was found that the weaker emulsions 

 of from 3 to 6 per cent strengths had all the desired penetrating quali- 

 ties and with httle or no injurious effect upon the trees. As the nico- 

 tine solutions killed all the thrips present and gave no spray injury 

 this led to a combination of the two in Contra Costa County in the 

 spring of 1909 with most satisfactory results. 



A tobacco extract containing 2| per cent nicotine, diluted at the 

 rate of 1 to 60 in a 6 per cent distillate-oil emulsion, killed all the 

 thrips touched and penetrated well into the pear cluster buds. The 

 pubescent covering of the individual buds in the cluster, being resist- 

 ant to water, seemed to act on the dilution in distillate-oil emul- 

 sion in much the same manner as the wick upon oil in a lamp. Vari- 

 ous other combinations of nicotine solutions with "lime and sulphur 

 solutions" and "lysol solutions" and "soap solutions" were tried 

 extensively, but none proved to be as effective and at the same time 

 as practical as the combination of distillate-oil emulsion and the nico- 

 tine solutions. 



DISTILLATE-OIL EMULSION. 



Homemade f reparation. — Because of its cheapness and greater 

 efficiency as a penetrating spray, and therefore a more satisfactory 

 killing agent, growers are strongly advised to make their own emul- 

 sions and, preferably, the soap, although the latter can usually be 

 depended on if bought from reliable dealers. 



Directions for moJcing. — To make soap use this formula or some 

 multiple of same: 



Water 6 gallons. 



Lye (98 per cent) 2 pounds. 



Fish oil I2 gallons. 



Put the water in a caldron or boiler and add the lye. When the lye 

 is thoroughly dissolved and the water boihng, pour in the fish oil, stir- 

 ring in the meantime, and boil slowly for two hours. When the soap 

 has boiled sufficiently it should give a ropy effect when stirred and 

 brought up upon the ladle. This formula gives about 40 pounds of 

 moderately firm soap. 



Growers are cautioned to buy only genuine fish oil and not a fish- 

 oil compound or a mixture of fish oils and vegetable oils. Herein lies 

 part of the secret of the penetrating efficiency of the distillate emul- 

 sions made by using animal-oil soap as the emulsifier. The cost of 

 the soap is $0.0165 per pound made from fish oil at 35 cents a gallon. 



The distillate-oil stock emulsion should be made as follows: 



Formula :« 



Hot water 12 gallons. 



Fish-oil or whale-oil soap 30 pounds. 



Distillate oil (raw) 30° to 34° Baume 20 gallons. 



a For a spray tank of 200 gallons capacity, five times this formula can be made at 

 one time. 



