STATE POMOLOGICAL SOCIETY. 49 



all three applications were made 90 per cent of the fruit was 

 sound and perfect. Only about 50 per cent of the same grade 

 was obtained where the first application was omitted. Nearly 

 all of the remainder of the fruit on this plot was scabby. 



Arsenate of lead as a fungicide. Perhaps the most striking 

 and certainly the most unexpected result of this series of experi- 

 ments is the discovery of the appparently high fungicidal value 

 of this well-known insecticide in controlling apple scab. Its 

 value in this respect has been entirely ignored in almost all 

 other work of this kind. In a large proportion of the apple 

 spraying experiments conducted in this country it has been the 

 practice to entirely overlook any possible fungicidal effect of 

 the insecticide used in the combined spray. 



At the last meeting of this society a speaker from out of the 

 state told you in a most emphatic manner that arsenate of lead 

 had no fungicidal value when used alone against apple scab. 

 At that time I had already obtained figures from a series of 

 three successive yearly experiments at Highmoor Farm from 

 which one could draw nothing but quite the contrary conclu- 

 sions. The data from the fourth of this series have just been 

 obtained. While the test for the current year was less severe 

 than usual, the results as far as they go do not contradict those 

 previously recorded. 



The first suggestion of the fungicidal value of arsenic of 

 lead for apple scab came in 1912. Then four pounds of the 

 paste form alone in 50 gallons of water gave as good or better 

 scab control than did a 3-3-50 Bordeaux mixture of lime-sulphur 

 plus two pounds of the paste to each 50 gallons of spray. No 

 unsprayed check plot was available that year. The arsenate of 

 lead plot was located at the corner of the orchard more exposed 

 to air and sun. It was thought that this might have been a 

 factor leading to the relatively small development of scab upon 

 it. This factor was eliminated in the later experiments. 



In 1 91 3, an unsprayed check plot was added and dry arsenate 

 of lead substituted for the paste. One plot was sprayed at 

 all applications with two and another with one pound of the 

 powder to 50 gallons of water, or equivalent to about four 

 and two pounds of the paste form respectively. Nearly 39 per 

 cent of the apples on the unsprayed plot were scabby. Almost 

 perfect scab control was obtained with Bordeaux mixture, the 



