226 



NINETEENTH REPORT. 



Table No. 3. Strains of Glomerella. 

 Temperature of the experiment, 18° C. 

 Culture, Glomerella rufomaculans grown on potato agar. 

 Portion of spore suspension and fungicide for plant, 0.2 ec 

 Age of culture, eight days. 

 Amount of nutrient agar per plate, 10 cc. 



Fungicide. Dilution. 



Time culture exposed to action of fungi- 

 cide (10% copper sulphate) minutes. 

 5 15 30 4.5 



N. 



X Signifies growth; signifies no growth. 



From this experiment it cannot be definitely ascertained whether these 

 were two strains or wOiether the North Carolina culture was more 

 resistant because .it had been more recently isolated. Unfortunately 

 shortly after this the North Carolina culture was lost and all the results 

 given in this paper are obtained from the use of the Massacluisetts 

 culture. The difference in the resistance of the two indicate strongly 

 the necessity of using a standard organism. Either of these causes would 

 tend to disqualify G. rufomaculans as a test organism. 



Endothia parasitica is better adapted to this work in some respects 

 tlian any of the other forms tested. Its slow growth, great susceptibility 

 to the action of lime sulphur, and variation in spore resistance, are the 

 disadvantages met with in its use. 



Both G. rufomaculans and Endothia parasitica were used as test 

 organisms but were tested separately, the two being used for comparison 

 only. 



MEDIUM. 



As potato agar is as well known and commonly used nutrient for the 

 culture of many fungi, this medium seemed to be best suited for work 

 of this nature. Hence a medium prepared according to the following 

 formula was used throughout the work: 



Finely cut peeled potatoes, 390 grams. 



Distilled water, 1000 cc. 



Heat in autoclave for 20 minutes at 15 pounds pressure. 



Fifteen grams of shredded agar were added to each liter of this filtered 

 decoction. Tlie reaction of the medium was corrected to read -|"10 

 Fuller's scale. 



