April, '21] GiDDiNGs: dusting vs. spraying 225 



neither dusting nor spraying gave much benefit and there was a heavy 

 loss of fruit in some parts in spite of very thorough dusting and spraying 

 by the growers. 



President W. A. Orton: Problem.s of plant pathology beginning 

 with truck crop diseases will be discussed by Mr. H. A. Edson of the 

 Bureau of Plant Industry. 



The discussion was informal and no paper was submitted. 



President W. A. Orton: The last paper is entitled "Problems 

 Associated with the Control of Plant Diseases in Orchards," and will be 

 presented by Mr. N. J. Giddings, Morgantown, W. Va. 



ORCHARD DUSTING VERSUS SPRAYING 



By N. J. Giddings, Morgantown, W. Va.- 



In the few moments available I wish to present first a note regarding 

 the use of dust on peaches ; second a brief review of our own experiments 

 with dust for control of apple diseases in West Virginia ; third to give a 

 more general survey of the work along that line ; and fourth to submit a 

 few home-brewed, and re-distilled statements for your kind consideration. 



There seems to be no question as to the effectiveness of sulphur dust 

 for the control of peach scab. In our experimental work the control 

 with dust averaged a little better than with spray. Our data on brown 

 rot control are rather inadequate because the amount of infection was 

 light, but the results indicated that the dust was just about as effective 

 as spray. The details of our work on peaches are given in West Virginia 

 Experiment Station Bulletin No. 167. Some investigators have re- 

 ported fruit and foliage injury from the use of sulphur dust on peaches, 

 but we feel that this injury can be reduced to a negligible minimum in 

 actual orchard practice in West Virginia. We found such injury only 

 when excessive amounts of material were used. 



The attractive features of dust applications were first brought to my 

 attention in 1912-13. Professor Peairs, our entomologist having had 

 experience with dusting, was favorably impressed with the method, and 

 anxious to give it a further trial. I was at least reasonably optimistic, 

 so our experimental work was undertaken with the most sincere hope of 

 success, supplemented by the determination that the work should be 

 thoroughly and carefully carried out. 



Our first work was conducted in orchards where scab failed to develop 

 sufficiently to warrant drawing any conclusions. For our later work we 

 were ver^^ careful to select orchards in which this disease was prevalent. 



