CHRYSANTHEMUM RUST 241 



The uredospores and teleutospores appear later in the 

 season, mostly on the leaves, the former as pale brown 

 pustules, which soon become powdery ; the latter form 

 blackish-brown powdery pustules. 



Preventive Means. — When plants are once attacked, 

 cure is practically impossible, as the mycelium is perennial 

 in the plant, passing the winter in the part below ground, 

 and growing up, year by year, with the new stems. 



If the disease appears, infected plants should be dug up 

 at once, and burned, care being taken to remove all the 

 underground parts, otherwise the disease will appear again 

 with the new shoots. 



CHRYSANTHEMUM RUST 



{Piiccinia hieracii^ Mart.) 



A specimen of a supposed new disease of cultivated 

 chrysanthemums was sent to Kew for examination by the 

 editor of the Gardeners' Chronicle in 1897. During the 

 remarkably dry summer of 1898 this disease spread to 

 such an alarming extent in the south of England and in 

 parts of France that cultivators of this favourite flower, 

 remembering the wave of fungous disease that rendered 

 the successful cultivation of the hollyhock a matter of 

 impossibility for some years, predicted for it a similar fate. 

 Fortunately the exercise of prompt measures averted such 

 a catastrophe. 



The uredo or summer fruit forms minute, snuff-coloured 

 clusters of spores on the under surface of the leaf. In 

 badly diseased examples the pustules are often so numerous 

 as to cover the greater part of the surface of the leaf. 

 Unless checked, this stage of the fungus reproduces and 



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