2G4 RErORT OF OFFICE OF EXPERIMENT STATIONS. 



may be depended upon to furnish from 85 to 05 per eent of sound 

 apples. It is recomnionded that the first application be made from 

 above downward and fi-oin the sides inward but not upward from 

 near the center of the tree. This application should be given innne- 

 diately after the petals fall, or at least within three or four days 

 after this occurrence. A second application is recommended within 

 ten days to two weeks after the first. These two sprayings, as just 

 stated, were found when carefully api)lied to protect from 85 to 95 

 per cent of the apples from infestation, while unsprayed trees com- 

 pared with them showed an infestation of from GO to 90 per cent of 

 the fruit. AVhile, as a result of the earlier experiments, the Utah Sta- 

 tion did not wish to discourage late spraying, it recommended very 

 urgently that the early spraying must be done with all possible 

 thoroughness. Paris green at a rate of 1 pound to 150 gallons of 

 water or arsenite of lime are the insecticides recommended. 



In later experiments at the same station the relative value of early 

 and late sprayings was directly tested, and an attempt was also made 

 to find out how the arsenicals destroy the larvae, and especially to 

 determine the value of early sprays in reducing the importance of the 

 second brood. In order to get accurate data on this subject the 

 injury of the first brood was separated from that of the second. All 

 apples on the experimental trees were counted during the first week 

 in August, and each one was examined to see whether it was infested 

 and whether the codling moth had entered at the side or in the calyx 

 end. At this time of year all worms of the first brood are of consid- 

 erable size and are easily distinguished from the small larvae of the 

 second brood. The windfall apples were also gathered every day, 

 examined, and counted. After extensive data of this sort had been 

 collected it was found that two early sprayings killed on an average 

 on each tree 220 of the larvae of the first brood and 35G of the larvae 

 of the second brood, or a total of 57G worms. Three late sprayings 

 killed on an average 3G9 larvae. It is therefore apparent that the two 

 early applications not only destroyed more larvae than the three late 

 sprayings, but, by greatly reducing the first brood, exercised a still 

 greater influence in diminishing the numbers of the second brood. 

 The two first applications were made, one immediately after the 

 petals fall and the other ten days later, while the late applications 

 were made August 1, August 15, and September 1. This series of 

 experiments was repeated in 1905, when it was found that the two 

 early applications gave an average of 98.9 per cent sound apples at 

 picking time. In Washington " it was found that about 40 per cent 

 of the larvae of codling moths will be found under bands if properly 

 jilaced on trees, and that these larvae reach the bands by crawling 

 down the trees. 



o Washington Sta. Bui. 69. 



