Appendix. 153 



PERIOD AND METHODS OF THE EXPERIMENTS. 



The experiments on which the above statement I'ests may be con- 

 veniently described in five lots: two with lime, sulphur, and blue vitriol; 

 two with lime sulphur and salt; and one, a special experiment, with both 

 these washes on trees covered by tents. Two of the four experiments 

 above mentioned — one with the California wash and one with the Oregon 

 wash — were begun March 3, and the other two (in which also both washes 

 were used) were begun March 5. The tent experiment was begun on the 

 21st of the month. Observations on all the lots treated were continued 

 until March 25; that is, twenty-two days for the first two lots, twenty 

 days for the third and fourth, and five days for the lot under tents. The 

 experiments consisted of a single application of the insecticide in every 

 case, with varying subsequent treatments of the different trees with 

 water. Frequent counts of dead and living scales were made for all of 

 the trees, no attention being paid in these counts to old scales, outworn and 

 dead, but only to those whose size and immature character showed that 

 they belonged to the new generation of the preceding fall. Counts of dead 

 and living scales were made in all cases either before or shortly after 

 the application of the insecticide spray. It was in this way ascertained 

 that an average of about fifty per cent of the immature scales were already 

 dead on these trees before the insecticide was applied; and that the 

 action of the insecticide was scarcely perceptible within the first twenty- 

 four hours. 



EXPEUIMENTAX TREES USED. 



Forty-three trees were used in all the experiments, twenty-five of them 

 apple trees and eighteen peacn. They varied in height from twelve to 

 eighteen feet; in spread of top from eight to twenty feet; and 

 in diameter of trunk from four to nine inches. The average height was 

 fourteen feet, and the average spread thirteen. Th% general condition of 

 these trees varied from "very poor" to "excellent" six of them being 

 described as "very poor," eight, as "poor," sixteen, as "fair," ten, as 

 "good," and three, as "excellent." Some of the peach trees were more 

 than half dead, and many of them in such a condition that the owners 

 were about to remove them. The dry weather of the preceding summer 

 had killed the young growth even on otherwise healthy trees, and in some 

 cases much of the older wood had also died from drouth. All the trees 

 were of course, infested with the San Jose scale, eighteen of them badly 

 so, and the others to a medium degree. 



WEATHER OF THE PERIOD. 



The weather of the experimental period was the ordinary variable 

 weather of an Illinois March, the temperature at seven o'clock a. m. 

 ranging from eighteen degrees F., on the eighteenth, to fifty-four degrees 

 on the fifteenth, and at noon, from thirty-four degrees on the eighteenth, 

 to eighty-eight degrees on the twenty-fifth. There was an unusual amoimt 

 of wind from the southeast — on not less than fourteen days out of the 



