New York Agricultural Experiment Station. 465 



reports of the American Carnation Society that it is unnecessary 

 to discuss them in detail here. It is sufficient to call attention 

 to a few erroneous ideas which are held by some florists. 



Strange as it may seem there are still some who do not know 

 carnation rust. In reply to a request for specimens of rust on 

 the variety Wm. Scott I received from Kentucky leaves affected 

 with bacteriosis. I have known of other cases in which these 

 two diseases have been confused. The most reliable test for rust 

 is the presence of the brown powder. The external manifesta- 

 tion of the presence of rust is in the production of chocolate- 

 brown, elliptical, blister-like pustules (sori, sing, sorus) on the 

 leaves and stem. If one of these pustules is rubbed with the 

 slightly moistened finger tip a fine brown powder clings to the 

 finger. This powder is composed of the spores or " seeds " of the 

 rust fungus. 



Some florists believe that rust is localized in those parts of the 

 plant where the pustules make their appearance. Upon this 

 theory as a basis they hope to eradicate the disease by the re- 

 moval and destruction of the diseased leaves. While such prac- 

 tice is to be commended it can not, reasonably, be expected to 

 effect a cure. The spread of the disease may be checked but 

 that is all. By the time the pustule appears the mycelium has 

 already spread to other parts of the plant. 



This leads us to the consideration of another erroneous idea 

 in regard to the circulation in plants. The circulation in plants 

 is quite different from that in animals; that is to say, in plants 

 the liquids do not follow definite channels in any sense homolo- 

 gous with the veins and arteries of animals, but instead, pass 

 from cell to cell directly through the cell-ivalls according to the law 

 of osmosis.* Consequently it is not possible (as some believe) 

 for rust spores, although of microscopic size, to be carried 

 from one part of the plant to another by means of the circulation. 

 Rust spores are never found on the interior of carnation plants 

 except in the immediate vicinity of the pustules. 



* If two miscible liquids are separated by a membrane each liquid will pass through the 

 membrane and become diffused throughout the other. This is known as the osmosis of 

 liquids. 



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