CONTROL OF CODLING MOTH IN COLORADO. 9 



By reference to Table 7 it will be noted that in each instance the 

 coarse sprays, as applied with the short rod and Bordeaux nozzle, 

 gave control inferior to that on the plats treated with the poles and 

 whirlpool-disk nozzles. Thus, plat I, fine spray, yielded 89.48 per 

 cent of fruit free from worms in comparison with 79.54 per cent in 

 plat II, which was treated with the coarse spray. In plat III, 

 sprayed with the disk nozzles, there was 85.05 per cent of uninfested 

 fruit, whereas in plat IV, treated by means of the Bordeaux nozzle, 

 there was but 71.06 per cent of fruit free from worms. Again, in 

 plat V, which was treated with the fine spray, there was 89.70 per 

 cent of worm-free fruit in comparison with 81.43 per cent in plat VI, 

 which was sprayed with the Bordeaux nozzle. The untreated plat, 

 plat VII, produced 30.98 per cent of fruit free from worms. 



It is the belief of the writers that the coarse sprays do not adhere 

 so readily to the fruit, especially to the waxy skin of apples of the 

 Ben Davis type, as do the fine mist sprays. It is believed further 

 that the distribution of the poison is more thorough with the spray 

 poles and disk nozzles than with the short rod and Bordeaux nozzle. 



The results of this experiment considered as a whole seem to show 

 that three cover sprays were more efficient than five. But this an- 

 omal}^ may perhaps be accounted for by the fact that there was no 

 fruit in plats V and VI the preceding year, it having been destroyed 

 by the spring freezes ; hence, there being no overwintering larvae on 

 these trees, the infestation came solely from moths that migrated 

 from other trees. 



A further study of Table 7 will show, as in the experiments of 

 1915 (Table 4), that the average number of worms per apple was 

 lowest where the best control was obtained, with a range in this 

 respect among the sprayed plats of from 0.14 to 0.40. In the 

 unsprayed plat there was an average of 1.43 worms per apple. The 

 spray material readily checked the worms from gaining entrance 

 through the calyx, over 90 per cent of the larvae having entered the 

 fruit through the side. In the sprayed plats from 2 to 9.99 per cent 

 of the wormy fruit was infested at the calyx while in the unsprayed 

 plat 28.43 per cent of the wormy fruit was caused by larvae that en- 

 tered by way of the calyx. 



The average number of stings in the sprayed plats for all apples 

 varied from 0.34 to 0.82 and in the unsprayed plat the average 

 number was 0.23. 



47056°— 21— Bull. 959 2 



