hon treatment was not effective on Cortland, as 

 Windus and Shutak (J. Amer. Soc. Hort. Sci. 

 102:715-718) also reported in 1977. 



The third experiment was designed to test 

 the importance of light intensity on scald sus- 

 ceptibility. In 1989 and 1990, Cortland apples 

 were enclosed individually in brown kraft paper 

 bags in mid-to-late August, and kept in these 

 bags until they were harvested. Bags had al- 

 most no effect on fruit temperature. Each year 

 two harvests were made. Bagging did not affect 

 fruit maturity significantly in either year (Table 

 3); however, it resulted in fruit with greater 

 scald susceptibility, and differences usually 

 were quite large. Thus, under our conditions 

 severe reduction of light intensity increased 

 scald susceptibility, but it should be noted that 

 even bagged fruit were becoming less scald sus- 

 ceptible with later harvest, indicating that 

 bright light is not required in order for the 

 maturity and temperature factors to affect scald 



susceptibility. 



These results showed that under our condi- 

 tions preharvest temperature was the most im- 

 portant factor affecting scald susceptibility of 

 Cortland and Delicious apples. In Figure 1, all 

 three years of data were used to illustrate this 

 effect. For Cortland, scald susceptibility began 

 to decline when the fruit had experienced 

 slightly less than 100 hours below 50°F between 

 August 1 and harvest. By about 150 hours, 

 susceptibility had fallen to the point where 40 to 

 50% of fruit scalded, and as they approached 200 

 hours, only about 10% scalded. Delicious re- 

 quired about 25 more hours below 50°F to reach 

 these same levels of susceptibility. 



The effects of temperature differences 

 among different harvests and years can be seen 

 in Table 1. For example, in 1989 no loss of scald 

 susceptibility of Cortland occurred when har- 

 vest was delayed from September 15 to 22, and 

 it can be seen that temperatures were continu- 



8 



FruH Notes, Summer, 1994 



