report identifies fmit of low scald susceptibility. This 

 categoi^ should represent fnait with little or no need 

 for DPA treatment. Identifying these fruit is of 

 particular interest because 1 ) scald control treatment is 

 expensive and inconvenient to apply, and 2) the 

 materials used are not acceptable to an increasing 

 number of markets. Clearly, if 20% of fruit in a lot 

 develop scald, this is unacceptable. However, when 

 we attempted to generate equations for forecasting 

 small amounts, for example, less than 10% .scald, we 

 were unsuccessful; there was simply too much 

 variation in scald development in the vicinity of 10%. 

 We therefore developed the equation to predict under 

 20% scald because it produced consistent results. If 

 the Index for the "scald resistant" equation (Equation 

 2) is greater than zero for a given day, location, and 

 starch score, then fewer than 207c of fruit harvested on 

 that day will be predicted to scald after 25 weeks of 

 storage. In addition, the higher the Index, the greater 

 the likelihood that fewerthan 207p of fmit will scald. It 

 also follows that the higher the Index, the less scald 

 one would expect. Tables I and 2 show how many fruit 



developed any scald-like browning (Table 1) and how 

 many developed "distinct scald" (Table 2). As the 

 Index increased, the amount of scald did indeed 

 decrease. There was some variability among orchards 

 and years, but the trend was there. What this means is 

 that an individual could base scald control measures on 

 personal experience about how much scald had 

 developed on fmit from this site in previous years, and 

 on how much risk the grower was willing to accept, 

 using the tables shown below as a guide. If the Index 

 for Equation 2 is greater than zero, low susceptibility 

 exists. As the number becomes increasingly greater 

 than zero, the risk of scald becomes progressively 

 smaller. 



A Simple Procedure for Using (he 

 Prediction Equations 



The equations presented earlier in this article can 

 be intimidating. However, they can be rearranged to 

 produce an easy-to-use system for tracking scald 

 susceptibility during the harvest .season. 



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



