368 



UNIVERSITY OF CALIFORNIA — EXPERIMENT STATION. 



solely through the hearty cooperation of Mr. Bogen, who at all times 

 gave freely of his time, money and counsel. 



The period covers the fruiting season of 1910 and 1911. The writer 

 had observed that in some instances pear trees sprayed with a heavy 

 solution of home-cooked lime-sulphur, which contained a large excess 

 of lime, were freer from attacks of thrips than pear trees in the same 



Fig. 2.- 



-Unspi-ayed trees at blossoming time. This tree is adjacent to tlie one sliown 



in figure 1. 



orchard which were not sprayed. From previous experiments it seemed 

 highly improbable that sulphur in chemical combination with the lime 

 was the active agency. The only other possible agency was the free 

 lime which Avas sufficient to make a thin whitewash. Acting on the 

 above suggestion in the spring of 1910, we sprayed four rows of pear 

 trees, thirty-one trees in a row, and three trees on each of the next 



