DUSTING AND SPRAYING EXPERIMENTS OF 1918 AND 1919. 15 



For comparison, one plot was sprayed with lead arsenate. Check trees 

 were left. The materials were used as follows: 



Plot 4. Calcium arsenate (dry), 1 Ib. in 50 (no lime). 



Plot 5. Lead arsenate (dry), 1*4 Ib. in 50. 



They were both used in combination with lime-sulphur diluted at the 

 rate of 1 to 40. The arrangement of the trees and plots is shown in 

 Chart IV. 



Applications. The four regular applications were made as follows: 

 1st. Cluster or pink application. 

 2nd. Calyx application. 

 3rd. Two weeks after the second. 

 4th. First week in August. 



All spraying was done with a spray gun and with high pressure. 



RESULTS 



Foliage Injury. The trees sprayed with lead arsenate were in good 

 condition. There was very little foliage injury. The foliage of trees 

 sprayed with calcium arsenate was severely burned. The leaves were 

 badly spotted and many leaves dropped. _ The injury was not of the 

 yellow-leaf type. 



TABLE VI. RESULTS WITH BEN DAVIS AT GRAND LEDGE, 1918. 



Insect Control. Both materials gave very good insect control. 46.8% 

 of the apples on the unsprayed tree were affected by codling moth. This 

 gave a good check on the insecticidal vvJue of the different materials. 

 The results of counts are given in Table VI. 



EXPERIMENTS IN 1919 



The work with apples in 1919 was done in two orchards near Grand 

 Rapids. The work consisted of a comparison of dusting with spraying 

 and testing several dry lime-sulphurs and some of the newer arsenicals. 



A TEST OF SULPHUR DUSTS LIME-SULPHUR SOLUTIONS 

 DRY LIME-SULPHURS AND B. T. S. 



A Duchess orchard of about 125 trees was used for experimental tests 



