Spraying Apple Orchards in a Wet Season. 369 



The foliage of the trees was uninjured, except in the case of the 

 Paris green applied aJone. Some treeis', and parts of trees, to 

 which this had been applied, looked thinner than the rest of the 

 orchard during the latter part of the season. The leaves were 

 undoubtedly somewhat injured by the Paris green but not suffi- 

 ciently to weaken the trees to any extent. The cause of the 

 injury is undoubtedly due to the amount of arsenHc which entered 

 into solution. Tliis was found by analysis to be about one-half of 

 one per cent (.63) of the total amount. The addition of a little 

 lime would have destroyed all caustic action, for no injury could 

 be seen where the BoiMleanx: combinations were used. A sample 

 of London purple has been analyzed by the station chemist. It 

 was found that about fifty per cent of the arsenic was soluble and 

 it is this dissolved arsenic which injures foliage.* On account of 



its caustic properties the London purple was used only in connec- 

 tion with the Bordeaux mixtura 



PART II. THE PREVALENCE OF APPLE SCAB. 



Early in October a circular was sent from this station asking 

 for information regarding the degree in which the varieties of 

 apples were attacked .by the scab fungus. The varieties were to 

 be divided into three classes: First, those whose market valuei 

 is practically rained every year, as the Fameuse, or Snow apples,*) 

 second, those whose market value is not seriously affected, as the) 

 Baldwins; and third, those which are entirely free from scab. 

 The division was to be based upon the amount of scab found upon 

 the fruit. Many growers responded. Although the data are not 

 so complete as might be desired, still the resistant powers of 

 many varieties are shown in the tables given below. The matter is 

 a difficult one to study and it is hoped that apple growers, in 

 whose interest this work is being done, will watch the diseasei 

 next summer and report any results that may be of interest in 

 time for publication in a succeeding bulletin. The newer varies 

 ties should receive particular attention, for among them there are 



* See Cornell Experiment Station Bulletin No. 18, July, 1890. 



47 



