460 



JOURNAL OF ECONOMIC ENTOMOLOGY 



[Vol. 8 



apples, and those so surrounded with foliage are invariably ruined. 

 This feeding on the fruit, though often not very extensive, devitali- 

 zes the apples to such an extent that they stop growing and drop. On 

 account of this existing condition, it was thought best to check up 

 the experiments as soon as the feeding period of the insects was 

 over rather than waiting until harvest time. In so doing, thinning 

 of the fruit was permitted on the plats where it was found to be nec- 

 essary. 



A thousand fruits or thereabouts were counted in the various experi- 

 mental plats and checks. These were made from representative 

 trees chosen at random in the plats. In comparing the results that 

 were obtained, it is clearly indicated that none can be pronounced 

 as efficient in controlling the leaf-roller, though some benefit may be 

 derived from as weak application as 2 pounds to 50 gallons. In experi- 

 ment 1, where 2 pounds to 50 gallons were employed in the delayed 

 dormant and in the pink sprays, a benefit of 9 per cent was obtained 

 when compared with the check. Contrasting this experiment with 

 3 in which the lead was omitted in the pink spray, the results clearly 

 show the time at which the poison is an active agent in destroying 

 the worms. In this experiment there is only a 3 per cent difference 

 between sprayed and unsprayed fruit. The inefficiency of the delayed 

 dormant spray is more clearly shown in experiment 4; here 4 pounds 

 of the lead arsenate were used to 50 gallons. The fruit count shows 

 a 27 per cent loss on account of roller injury or five tenths of one 

 per cent less than the check. This is 2.5 per cent more injury than 

 was obtained where the weaker arsenical was used. This discrepancy 

 falls within that allowed for experimental error. 



The extra two pounds of lead to 50 gallons of water in experiment 2 

 decreased the fruit loss by 3.8 per cent, giving a total fruit injury in 

 this experiment of 15 per cent or a reduction of a little less than 

 half of the losses that occurred on the unsprayed trees. 



In experiment 5, where lead arsenate at the rate of 6 pounds to 50 

 gallons was used in the two early sprays, more encouraging results 

 were obtained. Even with this heavy dosage, however, 11 per cent 

 of the fruit was found to be damaged. On trees heavily loaded with 

 fruit, a loss of this percentage would not be very severe as a large part 

 of this could be overcome by judicious thinning. In years of a light 

 crop, however, a condition which exists this year, and where all of the 

 fruit should be retained, more efficient remedial measures than arsen- 

 ical poisoning should be employed. Unfortunately, experiment 6 

 was conducted on Johnathans, a variety which is not subject to 

 severe attack, in Hood River at least, by the roller, so that compara- 

 tive data as noted in the other experiments were not obtained. 



