8 BULLETIN 1434, U. S. DEPARTMENT OF AGRICULTURE 
Control. — The disease is most abundant when three conditions 
prevail, namely, prolonged wet periods during the time the apothecia 
mature, rainy periods during blossoming time, and a plentiful supply 
of mummied berries to start the tip-blight infection. As already 
noted, hard rot rarely is troublesome on older bogs. This may be 
partly because these bogs are picked clean regularly and very few 
mummied berries are left to carry the disease over winter. Clean 
picking is recommended as an important control measure. Some 
evidence has been obtained that in the "hook" stage of the vines 
(just as they begin to bloom) Bordeaux spray helps to reduce berry 
infection, and it is believed that a thorough application of Bordeaux 
mixture to the vines just before ascospore discharge occurs will help 
to prevent tip-blight and thus reduce the possibility of berry infec- 
tion; but all attempts to prove this experimentally have failed because 
of the impossibility of locating in advance a place where the disease 
was going to be epidemic. 
BLACK SPOT OF THE FRUIT 
Under favorable weather conditions the fungus causing black stem 
spot sometimes attacks berries, producing conspicuous black sunken 
spots that vary in size from very small spots to lesions that involve 
more than half of the berry. The entire spot is filled with innumer- 
able young fruiting bodies of the fungus. Berries affected by this 
spot are found only in sections of the bog heavily diseased with stem 
spot, but are rarely noticed prior to harvesting. Black spot is readily 
distinguished from the black rot of the fruit caused by Ceuihospora 
lunata by the fact that it develops before harvest and is strictly a 
spotting disease, with spots decidedly sunken. When no secondary 
fungi follow the black-spot organism, the healthy portion of the berry 
remains perfectly sound and normal, whereas black rot involves the 
entire berry. 
Mature perithecia of the black-spot fungus were not found on the 
berry. Although the immature perithecia are present in large num- 
bers in all spots, the berries become so overrun with other fungi 
before spring (the normal time for the ascospores to develop) that 
it is impossible to find fruiting material of the fungus. 
Control measures for black fruit spot are the same as for black 
stem spot. 
, MINOR FIELD ROTS 
Botrytis, as noted above, rots berries which have been injured in 
the field. Such berries become softened and yellowish in color. The 
fungus often fruits around the edges of wounds made by the fireworm. 
Phomopsis rot sometimes develops shortly before harvest. Berries 
rotted by this fungus are rather firm and leathery and are likely to 
be yellowish to reddish yellow in color at this season of the year. 
Phomopsis is better known as a storage rot, but numerous cultures 
showed that this early developing rot is due almost exclusively to 
this fungus. 
Exobasidium vaccinii infrequently attacks the fruit also, producing 
somewhat raised circular red spots upon green berries. Curiously 
enough, this fungus produces its spores in the interior of the fruit, 
upon the wall lining the seed cavity, which is known to ha^ve stomata. 
