DECAY IN THE APPLE BARREL. 79 



■which grow nearly everywhere when circumstances favor them. 

 Their spores seem to be almost omnipresent, but they do not 

 possess the ability to penetrate tough substances, and the natural 

 skin of the apple is usually a barrier they can not pass. Of all 

 these molds the Penicillium glaucum, Lk., or commonly known 

 as the " blue mold/' is the one that causes the greatest destruction 

 in the storeroom. A large part of the rapid soft rot is due to the 

 Penicillium. 



In a few words let the work of the scab fungus be reviewed. 

 As the name indicates, it causes a scab upon the surface, the 



Fig. 3. — Apple Mold following Apple Scab. 



naturally smooth, tough skin is roughened, and minute cracks are 

 produced which in short replace the ordinary skin, impervious to 

 the blue mold, with a disrupted coat that furnishes both a fine 

 lodgment for the spores of the mold and the condition favorable 

 for their germination and the further rapid growth of the mold. 

 It is easy to conceive of the scab upon an apple being so slight 

 and superficial as not to affect its real value, but the one deface- 

 ment becomes the entrance of a decay germ, that in a few days 

 reduces the whole apple to a noisome mass of rottenness resulting 

 in a million spores or blue mold. To prevent the soft rot of the 

 apple in midwinter in the barrel, the trees need to be sprayed in 

 midsummer in the orchard, to check the development of the scab 

 that would otherwise furnish the place of entrance of the blue 

 mold. Fig. 3 shows an apple that, when harvested, had a number 

 of rough circular patches due to the scab fungus. When the 

 photograph was taken, each one of these spots was the seat of a 



