126 



FUNGOUS DISEASES OF PLANTS 



the blossoms the following spring. With the return of growing 

 conditions, fermentation may be set up and beads of the gummy 

 exudation produced. Since the beads contain countless quantities 

 of the bacillus, insects readily spread it to some blossoms ; thence 

 it is promptly carried by bees to greater distances. The organism, 



FIG. 33. PEAR FRUIT INFESTED WITH THE BLIGHT ORGANISM; BEADS 

 EXUDED IN MOIST CHAMBER. (Photograph by H. H. Whetzel) 



however, is not very resistant to conditions. It is killed by very 

 brief exposure to sunlight and by a period of drying. This latter, 

 however, seems remarkable, in view of the general experience that 

 no amount of cold can act unfavorably upon this organism. It is 

 possible, however, that the effect of cold in the absence of mois- 

 ture may be as disastrous as drying out. 



The characteristics of this organism according to Whetzel are 

 as follows : 



