ASCOMYCETES 



273 



Illinois amounting to $1,500,000. Apple growers have become 

 so thoroughly informed as to the destruction of this disease that 

 they have to a large extent adopted the remedies recommended 

 as a result of recent investigations, and steps are now very 

 generally taken to control this fungus. This general interest 

 which has been awakened will doubtless tend to diminish losses 

 in future years. 



Parts of the plant affected. Upon the apple the bitter rot 

 fungus is active chiefly as a fruit parasite, although branches 

 may also be affected. The first appearance of the fungus within 



FIG. 122. BITTER ROT OF APPLE 



the tissues of the fruit is made evident by a small brown spot 

 beneath the skin. In the field, commonly, a single infection, or 

 at most a few infections, are to be found upon one fruit. Under 

 exceptionally favorable conditions, however, numerous infections 

 may occur. In any case, the affected spot may increase rapidly 

 in' size, showing constantly a more or less circular outline with 

 a well-defined margin. So soon as the spot has attained a size 

 of one-fourth inch, more or less, the central portion of the 

 affected area is sunken, and this is followed by the further 

 gradual spread of the fungus throughout the fruit, and by the 

 appearance of pustules as subsequently described (Fig. 122). The 

 whole portion of the fruit affected by the fungus is decayed, and 



