228 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 14 



The data secured in Connecticut are of particular interest, and the 

 following figures are presented with due acknowledgments to Dr. G. P. 

 Clinton and Mr. E. M. Stoddard. 



Percentage of Scab in Plots 



Variety Check 



Fall Pippin 56.3 



Mcintosh 37.25 



Greening 10.85 



These figures indicate that the dust was of far greater relative effective- 

 ness where the amount of scab was slight than where the infection was 

 reasonably severe. On the other hand we myst keep in mind the fact 

 that this experiment deals with different varieties, and there may be 

 other factors which should be considered. In Pennsylvania Mr. R. C. 

 Walton called attention to the fact that their results with dust in 1919 

 were strongly negative and that the amount of infection was high, 

 while they secured far more favorable results in 1920 when the general 

 scab infection was much less severe. 



Nova Scotia, using four applications, and West Virginia, using three 

 applications in one orchard and four in another, also give evidence 

 which is distinctly unfavorable to sulphur dust. 



It might be mentioned at this time that in comparing these data I have 

 assumed that, if the sprayed plot gave over ten percent, more sound 

 fruit than the dusted plot under similar conditions, the dust was compara- 

 tively inefficient. 



The results reviewed for the season of 1920 are reasonably similar 

 to those for previous seasons but the time will not permit further dis- 

 cussion. 



Now I wish to present certain conclusions and suggestions based upon 

 our experiences in connection with this work in West Virginia, and the 

 available data from other sources. The problem, itself should receive 

 attention from three distinct angles (equipment, materials, and methods). 

 I have already stated what we believe to be'some of the more im_portant 

 improvements needed in the equipment for applying dust, and will not 

 stop to discuss further details here. When it comes to the question of 

 materials, I believe that we are grossly ignorant. Take for exam.ple the 

 one m.aterial, sulphur dust, when in contact uith living plant tissue, and 

 consider the factors mentioned in the following questions, as to their 

 influence on the fungicidal action, or the injuriously toxic properties of 

 this dust. 



'This was the so-called "3 in 1" dust, containing three percent, of nicotine. The 

 treated plots each received four applications 



