34 LEAD ARSENATE. 



All of the experiments made in 1907 were repeated this year with 

 the following in addition : 



Experiment 12. To test the effect of applying lead arsenate made from lead acetate 

 and sodium arsenate without removing any of the by-products formed; i. e., sodium 

 acetate, acetic acid, and a slight excess of lead acetate. 



Experiment 13. Same as Experiment 12, except that lime was added in the propor- 

 tion of 4 pounds to 50 gallons. 



Experiment 14. To test the effect of lead arsenate made from lead nitrate and 

 sodium arsenate without removing the by-products formed; i. e., sodium nitrate and 

 a slight excess of lead nitrate. 



Experiment 15. Same as Experiment 14, except that lime was added at the rate of 

 4 pounds to 50 gallons. 



In these four experiments the lead arsenate was applied in the same 

 proportion as in other experiments in which it was used; that is, on 

 the basis of 1J pounds of dry material to 50 gallons of water. 



Four apple and four peach trees were used for each experi- 

 ment. The first application was made on April 27 and the second on 

 May 8. On May 20 the third application was made on the apple 

 trees and Experiments 1 to 4 on the peach, when work was inter- 

 rupted by a very heavy rain (1.86 inches), foUowed by several days of 

 unsettled weather. On the 25th the remaining mixtures were ap- 

 plied, and Experiments 1 to 4 were resprayed. The latter, therefore, 

 had received four applications of lead arsenate, but as the third had 

 not had sufficient time to dry completely on the leaves before rain 

 fell it was undoubtedly largely washed off. The last application was 

 followed by five days of very hot, clear weather without rain. 



REdbRD OF OBSERVATIONS. 



When the last spraying was done, on May 25, there was no injury 

 apparent from any of the applications previously made. June 4 no 

 injury could be observed to any of the apple trees. The foliage of 

 the peach, however, showed very decided injury in some cases, as 

 noted below. 



NOTES MADE ON JUNE 4. 



Experiment 1. Quite a number of leaves had brown, shriveled edges and showed 

 the "shot hole" effect, the injury, however, not being severe. Experiments 2, 3, and 

 4 the same, accompanied in the latter case by slight dropping and yellowing of the 

 leaves. 



Experiment 5. Evidence of very slight injury; Nos. 6, 7, and 8, no injury. 



Experiment 9. Slight injury, some ''shot-hole" effect; no dropping of leaves. 



Experiment 10. Same as No. 9. 



Experiment 11. Same as Experiment 9, but more severe; some dropping of leaves-. 



Experiment 12. Showed some injury; leaves pretty badly spotted, and some had 

 dropped. 



Experiment 13. Same as Experiment 12, but not so severe. 



