Appendix. 155 



of a corresponding shower, since the water spray was not distributed 

 equally over the whole area covered by the tree top, but was made to 

 wet the tree equally in all parts; the middle part of the tree much more 

 freely, consequently, than the outer parts, it would doubtless be fair to 

 say that the fifteen-gallon portion was equivalent in effect on the average 

 experimental tree to a rainfall of a third of an inch, and the double por- 

 tion, of course, to twice that amount. The time taken for the application 

 of fifteen gallons varied, according to the weather and the size of the 

 tree, from twenty minutes to thirty or thirty-five, and for the thirty- 

 gallon application it was never less than an hour. The water in all cases 

 dripped freely from the trees for some time after spraying ceased, carry- 

 ing with it so much of the insecticide in solution that the drip was of 

 about the color of the original mixture. 



The applications of water were varied systematically as to number, to 

 frequency, and to period of time between the insecticide operation and 

 the first general wetting. Tree No. 1, for example, was wet every 

 day for a week, commencing the next day after the California wash was 

 applied; tree No. 2 was wet but once, and that the day after in- 

 secticide treatment; tree No. 3, was sprayed on the third with the 

 California wash, and with water on the sixth and every other day 

 thereafter for three days; tree No. 6, was sprayed but once, and 

 then with thirty gallons of water one week after insecticide treatment; 

 and tree No. 9, the same, except that the water was applied at the end 

 of two weeks. Further particulars may be obtained from the detailed ac- 

 counts of the experiments. 



EXPLANATION OF TABLES. 



The four tables in the text have been prepared to present in summary 

 form the detailed results of the treatment for each tree as shown by suc- 

 cessive counts of scales on selected sample twigs and branches. Against 

 the number of each tree is placed for each date on which special observa- 

 tions were made, the number of scales counted and the percentage of scales 

 killed by the insecticide up to that time. The first count shows always 

 the percentage of scales found alive at the time of treatment. The last 

 column in each table shows the final effect of treatment in the form of a 

 general average of all the percentages of scales killed, excluding only the 

 first seven days subsequent to the insecticide treatment. At the bottom 

 of each table is a series of data for the entire lot of trees, corresponding 

 in form to those given in the body of the table for each tree. 



EXPERIMENTAL DETAILS. 



First Lot of Trees. California yVash. 



Nine apple trees sprayed with lime, sulphur, and salt on the third day 

 of March. Weather partly cloudy, with cold raw wind from the east- 

 northeast; temperature, thirty degrees at seven a. m. and forty degrees 

 at noon. 



