14 THE CONTROL OF APPLE BITTER-ROT. 
points of infection are more commonly located on the sunny side of 
the apple. Although infections were frequently found on the shaded 
side of the apple, in the majority of cases, according to the writer’s 
observations during the past season, the rotten spots developed on the 
side exposed to the sun. 
Cold is decidedly unfavorable to the fungus and it rarely does any 
damage during a cool season. An outbreak may be almost completely 
checked by a few days of cool weather, especially when the mean tem- 
perature remains below 70° F. Late infections that take place with 
the approach of cool fall weather usually remain as a brown speck 
encircled with a red or purplish ring. However, the fungus grows 
somewhat in the average fall weather, and if the temperature runs up 
to summer heat the picked fruit may rot considerably in piles or in 
barrelsin the orchard. This emphasizes the desirability of rushing the 
fruit to cold storage or to market as soon as picked. In storage at a 
temperature of 35° F. the fungus does not grow, and spots previously 
started by inoculation develop no further after being stored at this 
temperature. 
SUSCEPTIBILITY OF DIFFERENT VARIETIES. 
There is a wide range of variation in the susceptibility of the dif- 
ferent varieties of apples to injury from bitter-rot. In Virginia the 
Yellow Newtown (or Albemarle Pippin) is preeminently the most sus- 
ceptible commercial variety. On the other hand, the Winesap is 
equally conspicuous for its resistance to the disease. When in close 
proximity to a badly rotting variety the Winesap may become infected, 
but the points of infection usually remain as mere specks, rarely grow- 
ing to any size. The fungus does not seem to thrive on this variety 
and the production of spores is scant. The Ben Davis, although one 
of the most susceptible varieties in the Middle West. shows a com- 
paratively slight tendency to rot in Virginia, rarely losing more than 
25 per cent of its crop. York Imperial, the variety most extensively 
grown in the Valley of Virginia, is less susceptible than Ben Davis, 
being rarely attacked to a serious extent. The Grimes also rots very 
little. 
From rather extensive observations made during 1908 and 1905 in 
Virginia and West Virginia the writer has prepared the accompanying 
list of varieties in the order of their susceptibility to bitter-rot. This 
list includes only such varieties as the writer examined in orchards 
where bitter-rot was found, and the data are not sufficiently extensive 
to be entirely reliable. Those varieties almost equally susceptible are 
grouped together, the first group representing those that frequently 
lose their entire crop, the second group those that ina bad season may 
be expected to lose 50 to 75 per cent of their crop, the third group 
those that rarely suffer more than 25 per cent loss, and the fourth 
elute 
