Minnesota Plant Diseases. 



355 



Among these molds the blue (or green) mold is perhaps the 

 most common. (See Chapter IX.) So common are the spores 

 of these fungi in the atmosphere that one can find them at all 

 times of the year, often in great abundance, everywhere. An- 

 other common soft-rot of fruits is found, in certain kinds of 

 black mold. (See Chapter VIII.) The effect of these rots is 

 a rapid softening of the affected parts of the fruit and, as the 

 fungus spreads, the fruit is finally entirely softened and rendered 

 worthless. The fungi gain entrance to the fruit chiefly through 

 wounds in the skin. Cracks in the skin, such as those caused 



FIG. 188. Blue mold soft rot of apple. After L. F. Kirrney. 



by apple scab, or holes formed by insects, or bruises and cuts 

 obtained in picking, packing and storing, all contribute to the 

 ease of entrance of the fungus. 



The prevention of ripe-rots is possible to a certain extent by 

 avoiding those conditions favorable to the entrance and growth 

 of the fungi. Warm moist atmospheres should be avoided, 

 hence cold storage of fruits is desirable. Spraying may reduce 

 other diseases, such as scab, and in this way prevent the ripe rots 

 which usually follow such diseases. The spraying on the tree 

 is not, of course, directly beneficial against the ripe-rot, since the 



