320 EXPERIMENT STATION— BULLETINS. 



A gentleman wishing to spray his orchard, in which he was pasturing 

 seventy-five hogs, consulted me as to the wisdom of doing so without first 

 removing the swine. I told him I believed there was no danger. I said 

 use a mixture, one pound of London purple to two hundred gallons of 

 water, watch your hogs closely and if any seem affected remove all at once, 

 and I will be responsible for damages to the amount of twenty-five dollars. 

 The gentleman did so and reports no damage. 



In the following experiments I used the mixture of twice the strength which 

 should be used, that the experiments might be the more convincing. I used 

 one pound to one hundred gallons of water. In every case the spraying was 

 very thoroughly done. Care was taken that every twig and leaf should be 

 drenched. 



In tree No. 1 a thick paper was placed under one-half of a rather small 

 apple tree. The space covered was six by twelve feet, or seventy-two square 

 feet. The paper was left till all dripping ceased. As the day was quite 

 windy the dripping was rather excessive. In this case every particle of the 

 poison that fell from the tree was caught on the paper. Dr. R. C. Kedzie 

 analyzed the poison and found four-tenths (.4) of a grain. Tree No. 2 was a 

 large tree with very thick foliage. Underneath this tree was a thick carpet 

 of clover, blue grass and timothy just in bloom. The space covered by the 

 tree was fully sixteen feet square, or equal to two hundred and fifty-six 

 square feet. As soon as all dripping had ceased, the grass under the tree 

 was all cut very gently and very close to the ground. This was taken to the 

 chemical laboratory and analyzed by Dr. R. C. Kedzie. There was found 

 2.2 grains of arsenic. Now, as our authorities say that one grain is a poison- 

 ous dose for a dog, two for a man, ten for a cow, and twenty for a horse, 

 there would seem to be small danger from pasturing our orchards during 

 and immediately after spraying, especially as no animal would eat the 

 gprayed grass exclusively. To test this fully, I sprayed a large tree over 

 some bright tender grass and clover. I then cut the clover carefully, close 

 to the ground, and fed it all to my horse. It was all eaten up in an hour or 

 two, and the horse showed no signs of any injury. This mixture, remember, 

 was of double the proper strength, was applied very thoroughly, and all the 

 grass fed to and eaten by the horse. This experiment was repeated with the 

 same result. I next secured three sheep. These were kept till hungry, then 

 put into a pen about a tree under which was rich, juicy June grass and 

 clover. The sheep soon ate the grass, yet showed no signs of any injury 

 This experiment was repeated twice with the same result. It seems to me 

 that these experiments are crucial and settle the matter fully. The analyses 

 show that there is no danger, the experiments confirm the conclusion. 



Thus we have it demonstrated that the arsenites are effective against the 

 codling moth, that in their use there is no danger of poisoning the fruit, 

 and when used properly no danger to the foliage, nor to stock that may be 

 pastured in the orchard. 



A. J. COOK. 



August 17, 1889. 



