April, '21] quaintance: dusting vs. spraying 221 



Industn' during the last few years in dusting of apple orchards in com- 

 parison with spraying. The results in so far as relating to details lack 

 much in definiteness and present frequent inconsistencies, but perhaps 

 not more so than happens in experimental work of this character. The 

 work was accomplished for the m.ost part in a thorough-going and effec- 

 tive manner by men experienced in this kind of experimentation. In 

 one or two instances the arrangement of plats in the experimental 

 blocks was not entirely satisfactory^ since it was not possible to obtain 

 orchards of sufficient size, and of the right varieties to obviate some over- 

 flow of dust from one plat to another. No attempt will be made to 

 draw detailed conclusions, as for instance, on the proper dosage of arsen- 

 ate of lead, the m^atter of diluents, number of applications, etc. Cer- 

 tain general conclusions however appear to be' warranted, which will 

 be given below. 



Table I gives results of dusting versus spraying apples at Benton 

 Harbor, Mich., carried out under the direction of Mr. F. L. Simanton 

 during the years 1915, 1916 and 1917, involving varieties of Rhode 

 Island, Ben Davis and Baldwin. In some of this work Mr. -Simanton, 

 was assisted by Mr. H. G. Ingerson and Mr. A. J. Ackerman, of this 

 Bureau and Mr. Leslie Pierce, of the Bureau of Plant Industry. 



In Tables II and III results are presented from Winchester, Va. of 

 dusting versus spraying of apples during 1917 and 1918, carried out by 

 Mr. B. R. Leach, of this Bureau. During 1917 scab results were not 

 taken on the York Imperial, nor in 1918, since this variety is very little 

 subject to this disease. Results on scab infection for 1918 however are 

 shown in the case of Ben Davis variety. 



Table IV presents results of dusting versus spraying of apples at Ben- 

 tonville, Ark., during 1918, carried out by Mr. A. J. Ackerman, of this 

 Bureau, and assisted by Mr. Leslie Pierce, of the Bureau of Plant 

 Industr^^ In this work, in addition to results on codling moth and 

 curculio, the effect of the treatm.ents on apple scab and apple blotch was 

 secured. 



Table V presents work accomplished at Wallingford, Conn., during 

 1918, carried out by Mr. E. H. Siegler and Mr. B. A. Porter on Mcintosh 

 and Baldwin varieties. Scab results were taken on the Mcintosh 

 variety, but as will be noted from the figures, there was practically no 

 scab present. 



Table VI presents results of dusting versus spraying of apples at 

 Grand Junction, Colo., on the Ben Davis variety during 1917. This 

 work was carried out by Mr. L. C. Antles and H. K. Plank of this Bureau. 

 Results on the codling moth only are presented, since in this arid, region 

 fungous diseases of the fruit are of no importance. 



