14 THE CONTROL OF APPLE BITTER-ROT. 



points of infection are more commonl}^ located on the sunn}^ side of 

 the apple. Although infections were frequently found on the shaded 

 side of the apple, in the majorit}" 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 completeh" 

 checked b}' 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 

 barrels in 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 previousl}' 

 started by inoculation develop no further after being stored at this 

 temperature. 



SUSCEPTIBILITY OP' 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 

 equal]}" conspicuous for its resistance to the disease. When in close 

 proximity to a badly rotting variety the Winesap ma}" become infected, 

 but the points of infection usuall}" remain as mere specks, rarely grow- 

 ing to any size. The fungus does not seem to thrive on this varietj'^ 

 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 extensivelj^ 

 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 1903 and 1905 in 

 Virginia and West Virginia the writer has prepared the accompan3ung 

 list of varieties in the order of their susceptibility to bitter-rot. This 

 list includes onh" 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 equalh' susceptible are 

 grouped together, the first group representing those that frequently 

 lose their entire crop, the second group those that in a bad season may 

 be expected to lose 50 to 75 per cent of their crop, the third group 

 those that rarely suflfer more than 25 per cent loss, and the fourth 



