Diseases and Injuries 



demonstrating the various mycelia which attack the carnation. As the result 

 of these papers and the discussions ensuing thereon, the carnation diseases 

 became familiar to those engaged in growing the divine flower, so that, at 

 the present time, practical growers have little trouble in diagnosing the differ- 

 ent forms of fungi which infect the carnation plant. 



Carnation Rust (Uromyces caryophillinus) 



When this disease was first introduced, about the year 1892, in some 

 localities it spread so rapidly over the carnation stocks, and caused so much 

 damage, as to excite the gravest fear among many that it would ultimately 

 destroy the industry. Happily, this fear was not well founded, and, at the 

 present time, this disease is not considered a serious ailment in most of the 

 etablishments where the plants receive proper treatment. 



The presence of this fungus is first indicated in the plant by a slight 

 swelling, either on the stem or leaf. The surface of these swellings soon 

 becomes pale, or nearly colorless, as the green coloring matter is destroyed 

 and obscured by the fruiting threads and young spores of the fungus. As the 

 fungus matures, these spores become brownish in color, and the mass lying 

 so closely together, imparts a dark brown color to the colony of fruiting 

 spores. As growth proceeds, the pressure from within ruptures the epidermis, 

 exposing the mass of spores. When the plant is thoroughly infected, 

 the foliage presents the appearance of being thickly covered with dark brown 

 powdery spots. 



Rust reproduces itself from two classes of spores. The first, called 

 "uredo spores," germinate readily in a moist atmosphere as soon as they are 

 set free ; and as these spores are easily scattered about and over the plants, 

 by winds or draughts, the disease spreads rapidly if conditions favor the 

 growth of the fungus. 



A short time after the development of the uredo spores, a second kind 

 of spore is produced, termed the "teleuto spore." These later spores will 

 not germinate immediately after development, but must first pass through 

 a period of rest, serving the purpose of tiding the parasite over any unfavor- 

 able periods when the uredo spores might fail to vegetate. 



The Rust attacks the carnation in every stage of growth, from the seed 

 leaf to the mature plants, cuttings in the sand bench being particularly 

 affected wherever they are taken from an infected plant. Frequently the 

 plant shows no external evidence of the disease for some considerable time, 

 but contains the threads within its tissues. In such case, the disease develops 



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