274 MANUAL OF FRUIT DISEASES 
the enlargement of the lesion the whole fruit becomes involved, 
is brownish, shrunken, and eventually shrivels into a dark 
mummy. The mummy may cling to the tree or it may fall 
to the ground. While on the tree mummies cling together 
in groups of two or more. 
Cause of brown-rot. 
The pathogene, the fungus Sclerotinia cinerea, hibernates in 
both the fallen and hanging mummies, and in thecankers. From 
sclerotial crusts in the fallen mummies arise apothecia (Fig. 74) 
in the spring of the 
year. The hanging 
mummies furnish a 
habitation for co- 
nidia through the 
winter; in the 
spring these spores 
are carried to the 
susceptible _ parts. 
Fic. 74. — Apothecia of the brown-rot fungus ; These old clinging 
attached to fallen mummies. mummies as well as 
the cankers also con- 
tain mycelium of the fungus, and in the spring conidia are 
developed from these sources. The source of the primary 
inoculum is found, then, in both the fallen and hanging 
mummies, and in the cankers. The inoculum itself consists 
of both ascospores and conidia, of which the latter are the 
more important. In fact, it sometimes appears that ascospores 
are not developed every year, and that they play a very 
minor réle in the life-history of the brown-rot fungus. Spores 
of either kind are carried to the blossoms, where blossom-blight 
is induced. The mycelium grows throughout the blossoms, 
enters the twigs, and finally passes into the large limbs. 
Conidial tufts develop on the petals, and even on the cankers 
and blighted twigs, if the atmosphere has a high relative 
