474 Report of the Mycologist of the 



The results of these tests are somewhat remarkable. Copper 

 sulphate is considered an excellent fungicide, but as a preventive 

 of the germination of carnation rust spores it is not nearly so 

 efficient as potassium sulphide. Copper sulphate, 1-300, failed to 

 wholly prevent germination, whereas potassium sulphide, 1-3000, 

 completely prevented germination. These studies taken in con- 

 nection with the results of our spraying experiments reported in 

 a subsequent part of this bulletin lead me to believe that the 

 beneficial results obtained by Prof. Taft* at the Michigan Agri- 

 cultural College were accidental and not due, as he supposed, 

 to the copper sulphate spray, 1-1000. No check is mentioned and 

 I think there was none. In the germination test, copper sulphate, 

 1-500 (which is double the strength used by Prof. Taft) did not 

 prevent germination. Generally the germination was less vigor- 

 ous than in the treated cells, but the germ-tubes appeared healthy 

 and capable of developing a mycelium if opportunity were offered. 



It was frequently observed that spores lying at the edge of the 

 hanging drop germinated sooner and more vigorously than spores 

 nearer the center of the drop. This happened in pure water as 

 well as in the fungicide solutions. The explanation of the phe- 

 nomenon is as follows: spores, like seeds, require oxygen for their 

 germination, and those spores lying near the edge of the drop 

 have a more abundant supply of oxygen. 



My results do not quite agree with those obtained by Wm. 

 Stuart. t In copper sulphate, 1-500, he made two cultures neither 

 of which showed any germination. I made sixteen cultures and 

 fifteen of them showed more or less germination. In copper sul- 

 phate, 1-1000, he made seven cultures of which five did not 

 germinate at all and two germinated nicely. I made four cul- 

 tures all of which germinated. I am unable to account for these 

 discrepancies except to suggest that in his tests of the 1-500 

 strength it may be possible that he accidentally used spores 

 which were incapable of germination under any conditions. This 

 sometime happens. 



• Taft, L. R., Carnation Rust Combated. Florists' Exchange, Vol. VII.. p. 123. 

 t Stuart, Wm., Some Studies upon Carnation Rust. 8th Ann. Rept. Vermont Exp. Sta. 

 1894, p. 116. Also American Florist, Vol. IX., July 36, 1S94, p. 1232. 



