260 Bulletin 177. 



the difficulty of securing power enough to mix the liquids and to 

 throw the spray the required distance. It is scarcely to be expected 

 that tlie automatic kerosene-and-water mixing pump can ever throw 

 a spray so far as one whicli expends all its energies in throwing the 

 spray. These automatic pumps are not yet perfect, but some of 

 them are perfect enough to be useful and reliable ; and they indicate 

 that we may expect better things. I do not say that the kerosene- 

 and-soap emulsion is already out of date — only that the indications 



are that it will become less and less important. 



* * * 



Shall white arsenic be used as a substitute for Paris green ? This 

 is not a new question. Experiments on this point were made by 

 Kilgore as early as 1890. The arsenic is combined with lime to 

 form arsenite of lime. There is no question as to the efficacy of the 

 mixture, or its safety on foliage. Our tests show that it is less 

 caustic than Paris green to foliage. We liave not recommended it 

 publicly because it is a dangerous thing to have the general run of 

 farmers buying white arsenic and mixing and boiUng it themselves. 

 One has only to inspect the ordinary farmstead to see how careless 

 the owner is about things which require careful liandling and weigh- 

 ing. The refuse is thrown in the yard or into a stream. Utensils 

 are left where they were used. There are farmers who are other- 

 wise, and if they have much spraying to do, the white arsenic can 

 be recommended confidently ; but I believe that most people should 

 buy their poisons ready prepared, even if the cost is somewhat 



greater. 



* * * 



The San Jose scale is still with us. It will stay. There is no 

 hope of eradicating it. Then every man should be prepared to meet 

 it. He should not rely on State control alone. 



For three seasons now, we have experimented with the kerosene 

 and water emulsion — as others have done — and have found that it 

 is a specific for the scale. In the jDroportion of 1 part of oil to 5 of 

 water in summer, and 1 to 4 in winter, it will kill the scale. 



Can a man hope to annihilate the scale, then, by spraying. No. 

 On plants which he can spray thoroughly and frequently, he can 

 hope to eradicate it; but I should not expect him to eradicate it 



