FUNGI INJURIOUS TO THE QUINCE. 157 
seen in Fig. 144. This decay is controlled by the fun- 
gicides to be later considered. 
THE QuINCE BLotcH.—The most obscure trouble of 
the quince that has been studied is what may be called 
the Quince Blotch. There is no decay, in the ordinary 
sense, connected with it, but the fruit when only partly 
grown becomes blotched with black. ‘This retards the 
growth of the immediate portion of the fruit, and soon 
the quince shows irregular depressions corresponding 
with the areas covered by the dark development. 
A fungus is constantly associated with this blotching, 
and by isolation it was found to grow upon a colorless 
jelly called agar, and produce spots that correspond in 
outline with those upon the quince. The pure virus of 
the blotch, removed from the culture tubes and intro- 
duced into holes and cuts in healthy fruit, will produce 
the first indications of the blotching, but in a few days 
some other germs find entrance and the experiment 
must close. 
OTHER DECAYS OF QUINCES. 
The fungi that have been briefly described do not 
include all that produce a decay and destruction of the 
fruit, especially after it has been gathered from the 
trees. The most rapid decay of all is due to the pres- 
ence of the black mould that causes the Soft Rot of the 
sweet potatoes, namely, Rhizopus nigricans, Ehrb. 
This mould does not seem able to attack the quince di- 
rectly, but gets a foothold through any bruised, cut or 
otherwise mutilated surface of the fruit. Some other 
fungus, which in itself is neither deep-seated nor, there- 
fore, serious, may prepare the way for the mould, and 
thereby be of much indirect damage. Fruit, for exam- 
ple, that may have only a few small patches of the ento- 
mosporium, or quince spot, is sometimes ruined by the 
rhizopus starting at the affected place and running 
