22 



EXPERIMENT STATION BULLETIN. 



CHART VI. Diagram showing arrangement of trees and plots in the O'Brien orchard at Grand 

 Rapids S Stark; C, check; O, other varieties; P, peach tree. Numbers indicate count trees. Plot 

 4 is in two parts. Plot 1, calcium arsenate; Plot 2, Corona lead arsenate; Plot 3, Magnesium arsenate; 

 Plot 4, Nurexform lead arsenate. The check tree next to the small portion of Plot 4 was used as a 

 cjunt tree. 



RESULTS 



Foliage Injury. The foliage of all trees sprayed with lead arsenate., 

 both Corona and NuRexform, was in very good condition throughout 

 the season. There was very little injury which was traceable to lead 

 arsenate. 



The trees sprayed with calcium arsenate showed foliage injury but 

 not enough to be classed as serious. 



Magnesium arsenate caused very severe foliage injury. This was not 

 evident until after the calyx application. In a few days after this ap- 

 plication, many leaves were spotted, turned yellow and dropped. The 

 effects of the injury caused by the calyx application had about passed 

 when the third application was made. The same process of leaves turn- 

 ing yellow and dropping developed again and continued for about two 

 weeks. The same thing happened again after the fourth application. 

 These trees lost fully half their foliage because of the injury by mag- 

 nesium arsenate. 



TABLE VIII. RESULTS ON STARK AT GRAND RAPIDS, 1919. ' 



