92 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. Asinglelesion 
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 
arule, 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 asa 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 
Fic. 25.— Soft-rot, or blue-mold. 
