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JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



things would happen :— (1) A very slovenly person would allow the dead 

 stems to lie on the ground, when, as already stated, the sclerotia would 

 remain until the following season, and then produce a crop of spores, and 

 the disease would appear again in due course. (2) The tidy man would 

 collect all the dead stems, and either deposit them in the piggery or 

 directly on a manure heap, a proceeding, from the point of view of 

 infecting a future crop, not more satisfactory than the previous method, 

 inasmuch as most of the sclerotia would find their way back to the land 

 along with the manure. 



1 



Fig. 307. — Tomato Leaf-rust {Cladosporium fulvum). 



Forms brownish velvety patches on the leaves, as in fig. 1. 2. Fruiting branches 

 of the fungus, x 400. 3. Spores of the fungus germinating, x 400. 



The only safe method of dealing vdih material infected with sclerotia 

 is to burn it. 



Many other kinds of fungi besides Botrytis form sclerotia. 



What has been stated respecting the origin of disease from the pre- 

 sence of sclerotia, unconsciously placed in the soil along with manure, 

 holds good for the many fungi that form winter-spores or resting-spores, 

 which remain in an unchanged condition throughout the winter and 

 germinate the following spring. Such spores often remain firmly fixed 

 to the host-plant they grew upon, not being destroyed by the conversion 

 of the material into manure, and in some instances will pass through the 



