If a sample fits neither of these categories, it is 

 considered to be of intermediate scald susceptibility. 

 Please note: There was a typographic error in one 

 equation in Fruit Notes 61(4). Those that we present 

 here are the correct equations. 



The numbers you get from these calculations are 

 called Indices. These Indices were tested in 1995, 

 1996, and 1997 a) for their ability to accurately place 

 samples in the correct scald category and b) to see if 

 they could be used as guides for application of the 

 scald inhibitor, diphenylamine (DPA). We also are 

 interested in relating the scald potential of controlled 

 atmosphere (CA)-stored fruit to the scald Indices. In 

 1 996 and 1 997, we stored fruit from the HRC in C A, as 

 well as in air storage. Scald symptoms on the CA fruit 

 were roughly parallel to symptoms on air stored fruit, 

 but affected a significantly higher percent of the fruit. 

 It is possible that this is because CA fruit were stored 

 for 28 to 29 weeks, while air-stored fruit were kept for 

 25 weeks. In CA, the specific atmosphere should 

 influence scald potential. Our storage atmosphere was 

 2.8% 0„ <2% CO,. Lower oxygen concentrations 

 ought to reduce scald, but we do not yet have adequate 



data to address specific questions regarding use of the 

 scald Indices to determine DPA requirements for CA- 

 stored fruit. 



Ability of Equations to Predict Scald 



Figure 1 shows how well the 1995, 1996. and 1997 

 samples fit the equations developed using the pre- 1 995 

 data. These samples included fruit from Storrs, CT, 

 Putney, VT, Durham, NH, and Monmouth, ME, as 

 well as the MA locations shown in Figure 2. In each 

 category, observed scald was only slightly different 

 from predicted scald, indicating successful application 

 of the equations to estimate scald potential at the time 

 of fruit harvest. 



Very Scald-susceptible Fruit 



Figure 2 shows the most scald susceptible samples 

 from Massachusetts, which were those from the first 

 harvest at each location. In all locations and years 

 scald did develop on more than 60% of these fruit. 

 However, responses to DPA varied by location. The 



n Fruit Predicted to Scald ■ Observed as Predicted 



80% 



■S 60% 



E 

 <o 



,2 40% 



c 



0) 



u 



o 20% 



Q. 



0% 



> 60% 



<60% <20% 



Number of Fruit Expected to Scald 



>20% 



Figure 1. Summary of results of scald forecasts: 237 samples, 9 orchards in Five states, 1995, 1996, 1997. Fruit 

 developing any scald-like. 



Fruit Notes, Volume 63 (Number 3), Summer, 1998 



