example, by summer pruning. Shaded fruit 

 probably require more cool temperature and 

 ripening to become less scald susceptible than 

 do exposed fruit. 



Our results show how rapidly scald suscep- 

 tibility can change during the harvest period, 

 and that cool temperature is the most important 

 factor in this change. In Figure 1 you can see 

 that if a couple of days occur when the tempera- 

 ture is almost continually below 50°F, scald 

 susceptibility can drop dramatically; this situa- 

 tion commonly occurs in early October in Massa- 

 chusetts. Conversely, if the temperature re- 

 mains constantly above 50°F for a period of time, 

 httle or no loss of scald susceptibility will occur, 



even though the fruit may ripen substantially. 

 We are attempting to develop a practical, 

 reliable predictive system so that growers can 

 estimate at harvest how scald susceptible their 

 fruit are, and determine their scald control 

 method according to need. At Belchertown, just 

 counting hours below 50°F at harvest has 

 worked well. In other regions, however, it is not 

 as effective, which raises questions about the 

 relationships between temperature and scald in 

 "unusual years" in Massachusetts. The results 

 here show that maturity and light also can be 

 important factors, and we hope to have a much 

 clearer picture of scald predictions in the near 

 future. 



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10 



Fruh Notes, Summer, 1994 



