112 SEVENTEENTH REPORT. 



are alike iu their effect on the cells of the host and we find a corky- 

 layer being formed in most cases to protect the host. 



The diseases all being caused by fungi of the same type and the 

 injuries being similar in their main characters, we must suppose 

 that a fungicide which controls all but one of them should be at 

 least partly effective against that one. It is hardly likely that 

 Bordeaux mixture should be useless as a fungicide in the case of 

 Cucumber Scab, when it is advised as a control for most of the 

 diseases caused by Cladosporium, There is no reason to believe 

 that Cladosporium cucumerinum is as resistant as would appear 

 from Frank's work, and the tests made by fungicides in the labora- 

 torj' have shown that this resistant quality, so long ascribed to it^ 

 is in reality lacking. 



FIELD EXPERIMENTS BY H. J. BUELL ON CONTROL OF SCAB. 



The work here referred to was done in the season of 1914: at Big 

 Rapids by Mr. H. J. Buell for the H. J. Heinz Co. The different 

 fields were spraj-ed on one-half and the other half left as a check. 



The mixture used was a 3-6-50 Bordeaux mixture, applied at the 

 rate of 200 gallons per acre. The fields were sprayed in regular 

 order, the first being sprayed again as soon as the last was finished. 

 Approximately a week was required for the round. All spraying 

 was done with a barrel sprayer, holding 50 gallons, mounted on a 

 cart and fitted with a 12 foot hose and an eight foot bamboo spray 

 rod, carrying two Yermorel type nozzles. 



The Big Rapids district was the center of the most severe attack 

 of scab noted in 1914 and as none of the fields outside of those in 

 the experiment were sprayed, there were unusual difficulties in the 

 way of successful control. 



As some of the fields sprayed seemed to show partial control by 

 the spray and others did not, Mr. Buell's records were examined to 

 see if they could throw any light on the matter. This examination 

 showed a seeming correlation between the amount of disease and 

 the time of spraying with reference to rain periods. 



The data on rainfall was obtained from the records of the United 

 States Weather Bureau and is given under Temperature and Hu- 

 midity relations. 



In these sprayings, we have both extremes, the spray applied just 

 before a rain and just afterwards. The difference in effect of the 

 two methods was verv marked in its results as is shown below. 



