6 



BTJLLETIlSr 959, U. S. DEPAETMENT OE AGRICULTURE. 



throughout the orchard. Plat III, in which three cover appHcations 

 were made for the first brood and two for the later broods, produced 

 the best crop of apples from the point of insect control, 72.22 per cent 

 of the fruit being free. from worms. Plat I V was treated with the 

 same number of cover sprays as plat III, but the number of applica- 

 tions for the broods was reversed, and with this treatment 66.48 per 

 cent of the fruit was free from worm infestation. In plat V only 

 three cover sprays were applied, and the treatment resulted in 62.21 

 per cent of uninfested fruit. As previously noted, plat VI was 

 sprayed five times by means of Vermorel nozzles with a pressure of 

 but 90 pounds, producing a very fine mistlike spray. Generally 

 speaking the results indicate that this treatment was as effective as 

 the other methods employed, there being 63.78 per cent of worm-free 

 fruit. The low-pressure mist spray also gave as good results as the 

 high-pressure coarse sprays in preventing the entrance of larvae 

 through the calyx end of the apple. It should be borne in mind, 

 however, that in commercial spraying a reasonably high pressure of 

 200 to 250 pounds will increase the speed of the work and that the 

 distribution of the spray material is likely to be more thorough than 

 when applied under a low pressure. 



Arsenate of lime, both homemade and commercial, as used in plats 

 VII and VIII, gave comparatively poor results. 



The unsprayed or check trees, plat X, were very wormy, giving 

 but 13.51 per cent of fruit free from larvae. 



The sprayed fruit was well protected against the calyx entrance 

 worms except in plat VIII. With this exception, the percentage of 

 wormy apples infested at the calyx in the sprayed plats varied from 

 3.72 to 5.92. The unsprayed plat produced 55.06 per cent of wormy 

 fruit infested at the calyx. 



Table 4. — Summary of results of spraying for the codling moth, Johnson orchard, Grand 



Valley of Colorado, 1915. 





i 



1 



i 



o 



'ft 

 ft 



ll 



o'S" 



o ^ 



§.3 



o 



S ft 



a 



Is 

 ""ft 



o ft 



al 



3 O 



Per cent of worms 

 (including extra) 

 entering apples. 



Per cent of wormy 

 apijles infested. 



u 



a 



1 



§3 ft 



a^ 



a 



ca . 



ia 



ft,. 



Plat. 















03 q 



03 ^ 







a 



« o 



M 



© I- 



^ 



o 



g 



^ 



^ ■ 



a 



fl 



aS 



piii 



"S"" 











03 



03 





•V 







•o 







C3 









3 



OS 

 o 



03 



> 



> 



o 





S 



O 





H 



1 



t 



;-( 



fs 





'A 



tH 



&^ 



< 



< 



< 



< 



-< _ 



< 



< 



< 



■< 



Ph 



pm 



I 



5 



4,208 



2,952 



0.70 



1.59 



2.34 



97.43 



0.24 



3.72 



95.91 



0.38 



5,306 



1.26 



40.54 



55.87 



II 



12 



9,356 



7,347 



.79 



1.67 



■ 3.17 



96.49 



.34 



5.29 



94.38 



.34 



17, 873 



1.91 



33.56 



52.88 



Ill 



6 



2,192 



844 



.39 



1.39 



3.44 



96.09 



.47 



4.76 



94.58 



.66 



2,067 



.94 



52.12 



72.22 



iv: 



i> 



3,174 



1,523 



.48 



1.43 



4.14 



95.40 



.46 



5.92 



93.52 



.56 



3,131 



.99 



44.27 



66.48 



V 



7 



6,005 



3,567 



.59 



1.57 



2.75 



96.92 



.34 



4.32 



95.24 



.44 



5,549 



.92 



53.51 



62.21 



VI 



7 



3,708 



2,013 



.54 



1.50 



3.87 



95.83 



.30 



5.81 



93.89 



.30 



3,450 



.93 



48.50 



63.78 



VII 



4 



1,785 



2,182 



1.22 



1.86 



2.38 



97.25 



.37 



4.42 



95.15 



.43 



2,098 



1.18 



56.49 



34.17 



VIII.... 



3 



1,601 



2,308 



1.44 



2.00 



6.50 



93. 15 



.35 



12.98 



86.76 



.26 



1,320 



.82 



52.36 



27.80 



IX 



10 



7,613 



3,438 



.45 



1.43 



3.72 



95.75 



.52 



5.32 



94.18 



.50 



7,337 



.96 



49.39 



68.41 



X 



3 



2,820 



5,077 



1.80 



2.08 



26.45 



72.31 



1.24 



55.06 



43.87 



1.07 



333 



.12 



90.03 



13.51 



