ORCHARD Sl'RAVIXG EXPHRIMEXTS IX I912. 



71 



While the use of these substances as a substitute for the ordi- 

 nary form of arsenate of lead as an insecticide is primarily a 

 problem of economic entomolog}', their effects upon foliage and 

 fruit, injurious or otherwise, are matters which concern the 

 pathologist. Therefore an experiment was conducted, with the 

 object in view of determining whether or not these substitutes 

 produce injurious eft'ects, in which the ordinary form of arse- 

 nate of lead paste was compared with the dried or powdered 

 arsenate of lead and the arsenite of zinc. 



For this Ben Davis trees were used in blocks of 36 trees each. 

 The records were taken on the fruit from one row of 6 trees 

 near the center of the plot as was the case in the fungicide ex- 

 periments. So far as could be observed none of the insecticides, 

 all of which were used in connection with standard dilution 

 lime-sulphur, produced any appreciable injury to the foliage. 

 Three pounds of arsenate of lead paste, i 1-2 pounds of the dry 

 arsenate of lead and one pound of arsenite of zinc were used 

 with each 50 gallons of the lime-sulphur spra3\ The following 

 gives in tabular form the condition of the fruit when harvested. 



Results of the Ixsecticide Experiments ox the Fruit. 



Tre.^tmext. 







; c^'o 



Zg 



"' 



Z2 



fii 



Arsenate of lead paste 



6733 



6080 



3 



650 



90 









Arsenate of lead dr\' 



3594 



33S3 







209 



94 









Arsenite of zinc 



5790 



5485 



5 



300 



93 



In the above table the term "sound" is used to include all 

 apples which were not attacked by insects and were not russeted. 

 In this experiment no account was made of scabby fruit. 



