230 NINETEENTH REPORT. 



Table No. 4. 



Fungicide, Ammoniacal copper carbonate, lOOx standard. 



Organism, G. rufomaculans on potato agar. 



Age of culture, four days. 



Amount spore suspension and fungicide per plate, .2 cc. 



Amount potato agar per plate, 10 cc. 



Temperature of incubation, 28° C. for four days. 



X=growtli. 



0^=no growth. 



Ammoniacal m- /■ 



^ , lime 01 exposure . 



Copper carbonate Dilutions. 



lOOx standard. 



in minutes. 



1-5 1-75 1-100 1-200 1-300 



15 O X X X X 



The results shown in the table indicate that tlie points to be determined 

 will lie between the dilutions 1-5 and 1-75 for the 15 minutes' exposure. 

 The 45- and 5-minute exposures would be likely to call for a greater or 

 less dilution respectively, but ought at least to fall within the dilutions 

 1-1 and 1-100. This was later found to be the case. 



RESULTS. 



A series of preliminary tests similar to the one mentioned above were 

 performed with Bowker's Lime Sulphur. P'rom these tests dilutions of 

 the 1-40 standard from 1-200 to 1-300 with intervals of 20 were deter- 

 mined upon. The 10% copper sulphate standard was prepared in 

 dilution from 1-5 to 1-35 with intervals of 5. Treatment of the spores 

 of Glomerella rufomaculans according to the method stated above gave 

 the results shown in Table 5. 



Similar tests, using G. rufomaculans, were made with tlie following 

 lime sulphur preparations : Dow Chemical Co., Grasseli Chemical Com- 

 pany, Thomas Chemical Co., Sherwin Chemical Company, Blanchard 

 Chemical Company, and the South Haven Chemical Company. The re- 

 sults obtained from these tests are embodied in Table 5. 



Table No. 5. 



Temperature of exposure, 18°-21° C. 



Cultures, Glomerella rufomaculans (cingulata) on potato agar. 



Age of cultures, 4-8 days. 



Amount of spore suspension and fungicide i)er plate, 0.2 cc. 



Amount of potato agar per plate, 10 cc. 



Temperature of incubation, 28° C. for four days. 



