CONTKOL OF CODLING MOTH IN" COLORADO. 29 



SUMMARY OF RESULTS. 



The principal points of interest in connection with the experi- 

 mental spray work in the Grand Valley of Colorado may be briefly 

 summarized as follows : 



Season of 1915. 



The highest percentage of fruit free from worms obtained in the 

 experimental plats in 1915 was 72.22, in a plat which received six 

 applications of arsenate of lead paste, 2 pounds to 50 gallons. In 

 the unsprayed plat there was but 13.51 per cent of worm-free fruit. 

 Arsenate of lime, both homemade and commercial, gave poorer 

 control than arsenate of lead. In the control of larvae that attempt 

 to enter the fruit by way of the calyx cavity the results indicate that 

 a low-pressure fine mist spray is as effective as a high-pressure coarse 

 spray. The number of stings per apple was considerably less in the 

 unsprayed than in the sprayed fruit. 



Season op 1916. 



The best result during the season of 1916, 89.7 per cent of the fruit 

 free from worm infestation, was obtained in a plat sprayed four times 

 with arsenate of lead powder, 1 pound to 50 gallons. In the unsprayed 

 plat 30.98 per cent of the fruit was uninfested. The primary object 

 of the season's work was to test a coarse spray applied hy means of a 

 short rod equipped with a Bordeaux nozzle in comparison with a fine 

 spray applied with spray poles and whirlpool-disk type nozzles. The 

 results indicate that better control was secured with the finer sprays 

 applied with the spray poles. 



Season of 1917. 



The highest percentage of fruit free from worms in 1917 was 78.06, 

 as a result of six applications of arsenate of lead, 1 poimd of the 

 powder to 50 gallons of water, to which fish-oil soap was added at 

 the rate of 2 pounds to 50 gallons. Two unsprayed plats yielded 

 8.83 and 8.54 per cent of fruit free from worms. Another plat 

 sprayed with six applications of arsenate of lead, but without fish-oil 

 soap, produced 62.10 per cent of worm-free fruit, thus indicating 

 that the addition of a soap spreader was of some value. The results 

 with the codling-moth trap did not indicate that it materially aided 

 in the control of the codling moth during the time of the experiments. 

 Nicotine sulphate gave poor control and in combination with arsenate 

 of lead apparently had very little value in reducing worm infestation 

 or sting injury. Arsenate of lime gave unsatisfactory results. The 

 dust treatments were even more ineffective. The plat in which Ihe 

 calyx spray was omitted was heavily infested at the calyx end. 

 Five spray applications produced practically as much good fruit as 

 seven. 



