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MANUAL OF FRUIT DISEASES 



affected fruit. The rotten area itself is very soft, watery and 

 light or yellowish brown in color. In the case of lesions involv- 

 ing a considerable portion of the apple the skin becomes wrinkled 

 (Fig. 25) , sometimes in a concentric manner. These changes are 



accompanied by a 

 characteristic moldy 

 taste which is de- 

 cidedly unpleasant. 

 Young spots may 

 begin anywhere on 

 the surface of the 

 fruit where there is 

 a rupture in the 

 skin. A single lesion 

 may develop at such 

 a rate as to involve 

 the whole fruit in 

 two weeks or less. 

 The rot is primarily 

 one of ripe apples; 

 green fruits are, as 

 a rule, not affected. Under conditions of high relative humidity 

 bluish or greenish blue mold tufts develop profusely over the 

 diseased area (Fig. 25). 

 Cause. 



The most important organism concerned in soft-rot is the 

 fungus Penicillium expansum. It is very likely, however, that 

 several other species of Penicillium may at times be responsible. 

 The above-mentioned pathogene is generally familiar as an 

 enemy of fruits. It grows as a saprophyte on a large number of 

 dead organic materials and produces a vast number of spores 

 which are omnipresent. These spores float abundantly in the 

 air and ultimately come to rest on various objects, fruits in- 

 cluded. Whenever one of these spores falls into a wound of any 



FIG. 25. Soft-rot, or blue-mold. 



