54 



S. E. A. McCallan 



The fungicide to be tested was sprayed or dusted into open petri dishes. 

 Liquid fungicides were allowed to dry thoroughly. Distilled water was 

 then added to each, about 10 cubic centimeters to a dish, and the whole 

 was allowed to stand exposed to the air for 24 hours. The suspensions 

 were then filtered through filter paper and the filtrates tested for free 

 copper with potassium ferrocyanide. None was found in any test. 



Coincidentally, similar but freshly made protectants were applied to 

 glass slides. No free copper was detected here with potassium ferro- 

 cyanide. After the liquid fungicide had thoroughly dried, spore-germina- 

 tion tests were performed, (a) in the filtrates and (b) directly on the 

 sprayed or dusted slides. 



The average of three tests with bordeaux mixture 4-4-50, no-excess- 

 lime bordeaux 2.5-2-50, and copper-lime dust, are given in table 7. 



TABLE 7. Percentage Germination of Sclerotinia Americana Coniuia 



Tests were likewise made with copper carbonate and copper hydroxide. 

 The copper carbonate was obtained from four sources and all was C. P. 

 material. The fourth sample was carefully and thoroughly washed and 

 dried before testing. The copper hydroxide, also C. P., was obtained 

 from two sources. Two separate tests, each in duplicate, were made on 

 all of these materials. The spores were from 5 to 7 days old. The results 

 are shown in table 8. 



TABLE 8. Percentage Germination cf Sclerotinia Americana Conidia 



Discussion. The results of the first series of experiments show clearly 

 that, practically no copper goes into solution in the distilled water which 

 stands on (fie bordeaux mixtures and the copper-lime dust. It therefore 



