CONTROL OF CODLING MOTH IN COLORADO. 11 



A series of experiments was conducted in the Nettleton orchard, 

 but the results were largely vitiated by frosts during May shortly 

 after the setting of the fruit. As a consequence of the low tempera- 

 tures, small frost pits or cracks in the epidermis developed in much 

 of the fruit, particularly around the calyx end of the apple. It was 

 practically impossible to force the spray material into these pits 

 which thus served as an ideal place of entrance for the worms. 

 Since the frosted fruit was unevenly distributed in the several plats, 

 there was no fair basis on which to draw a comparison of the value 

 of the different treatments. 



SPRAYING EXPERIMENTS IN 1917. 



The major part of the experimental spray work during the season 

 of 1917 was done in the orchard of the George Smith estate, at 

 Orchard Mesa. This orchard consisted of approximately 20 acres of 

 Ben Davis apple trees about 20 years of age and of fairly uniform 

 size and vigor. The orchard was divided into 17 blocks, or plats, 

 all of which were treated, except the two check plats XA^I and 

 XVII, located in diagonally opposite corners of the orchard. The 

 treatment of the several plats and the schedule of applications are 

 presented in Tables 8 and 9. 



A power sprayer delivering about 225 pounds pressure was em- 

 ployed in all of the liquid-sprayed plats, and a power dusting ma- 

 chine was used in the three dust-treated plats. With the exception 

 of plats XIV and XV, which were sprayed by the owner, all of the 

 plats were cared for by the experimental force. In the first or 

 calyx treatment the sprayed plats were sprayed by means of two 

 spray poles, equipped with Bordeaux nozzles, one of which was 

 operated from the spray tower and the other from the ground. In 

 applying the cover sprays, the Bordeaux nozzles were replaced by 

 the whirlpool-disk type nozzles, except in plats XIV and XV, 

 which were treated by the owner. In plat XIV the use of the Bor- 

 deaux nozzles was continued, for the cover applications, throughout 

 the season; in plat XV a spray gun, operated from the ground, was 

 employed for aU cover sprays. 



