1985 1986 1987 1988 1989 1990 1991 1992 1993 1995 1996 1997 1998 



Harvest year 



Figure 3. Year-to-year variation in mean scald development on HRC-grown Cortland apples (means corrected to 

 account for differences in harvest dates each year). 



susceptibility of Cortland apples from the HRC in 

 Belchertown, MA. Scald always occurred, but it was 

 much worse in some years (e.g. 1985 and 1993) than in 

 others (e.g. 1988 and 1997). Thus, some years were 

 "bad scald years" while others were not, although no 

 year was scald-free. 



In Figure 4, you see orchard-to-orchard variation 

 in Cortland scald development in New England. No 

 particular pattern is evident, except that 1997 seems to 

 have produced less scald than 1995 or 1996. Even this 

 difference may be confounded by the fact that the 1997 

 samples were harvested on average 3 days later than 

 the 1996 samples, but with an average starch score of 

 3.6 in 1997 vs 3.8 in 1996 (i.e. fruit were harvested 

 slightly later, but slightly less ripe in 1997) . That the 

 fruit from Monmouth, ME did not develop more scald 

 than they did seems remarkable, since those samples 

 were exposed to less cool weather (8 days of sub50"F 

 before harvest for ME vs overall mean of 1 7 days) than 

 were any other group of samples, had the lowest starch 

 scores (ME mean of 2.5 vs overall mean of 3.9 ), and 

 were among the earliest harvested (ME mean of 

 September 27 vs. overall mean of October 3). All 

 those factors generally are considered "scald 

 enhancing." 



Time of harvest is a major factor in scald 

 susceptibility of apples, and it is certainly a factor for 



Cortland. Figure 5 presents a composite of scald 

 development on all of our samples, across years and 

 sites, based on harvest date of the fruit. Cortlands 

 picked before September 21 were extremely scald 

 susceptible, while those picked after October 20 

 developed almost no scald, regardless of year or 

 growing site. Between these extremes, susceptibility 

 gradually fell as harvest date was later. However, 

 delaying harvest until fruit have low susceptibility 

 clearly is not desirable. Not only do they become 

 excessively soft, but they also become susceptible to 

 senescent breakdown, which occurred in 30% of fruit 

 harvested after October 15. 



Since there is so much variation in Cortland scald 

 susceptibility, an effective method of predicting 

 poststorage scald development at the time of harvest 

 could be very useful in guiding strategies to control 

 scald, e.g. whether or not to apply DPA, and , if so, 

 what concentration to use. However, none of the 

 equations we have created to relate preharvest 

 conditions, such as we described for Delicious in the 

 Spring 1998 issue of FruitNotes, have given reliable 

 results in separating lots of fruit by their relative scald 

 susceptibility. In Figure 6 are presented 10 years of 

 results from the HRC, comparing percent scald 

 "predicted" (in hindsight) from harvest date, starch 

 score, and number of preharvest sub 50"F days to 



Fruit Notes, Volume 64 (Number 2), Spring, 1999 



