SPRAYING FOR THE CONTROL OF APPLE SCAB. 



Professor H. H. Whetzel, 

 Cornell University, Ithaca, N. Y. 



The Scab an Epidemic Disease. The apple scab is a 

 disease distinctly epidemic in character, appearing with 

 marked severity some seasons, being almost entirely want- 

 ing in others. This marked difference in the abundance oi 

 the malady may occur in two succeeding seasons. While 

 appearing in epidemic form throughout the apple growing 

 regions only at rather long intervals, it is nevertheless epi- 

 demic in some section of the country nearly every year, as 

 for example during the season just passed (1912), the dis- 

 ease was very severe in Maine, but almost entirely absent in 

 New York. An examination of the records available indi- 

 cate that the scab has been generally epidemic throughout 

 the United States at rather regular intervals every few 

 years. Since there has been but little scab generally for the 

 past three or four years, due largely to the dry seasons which 

 have been general it would appear that we are approaching 

 another epidemic period for this disease. I have chosen for 

 several reasons to confine my remarks to the control of ap- 

 ple scab, rather than to those troubles such as lice, etc. which 

 have more particularly concerned you during the past sea- 

 son or two. First I am not a "bug" man and so am in no 

 position to advise you in matters relating to your insect 

 troubles. Second, because the past history of scab epidem- 

 ics indicate that your chief concern in orchard troubles for 

 the next two or three seasons is to be the apple scab rather 

 than lice. The scab may not be upon you in full force next 

 season but rest assured it will come and that right soon. It 

 is but the part of wise and sensible men to arm yourselves 

 with the best and most recent knowledge of this your enemy 



