serious financial losses. Thus, we are continuing to try 

 to refine our scald prediction system. 



The effects of warming on scald control on Deli- 

 cious were just as we hypothesized. Warming reduced 

 scald at all harvests, but only when susceptibility was 

 relatively low did warming provide satisfactory scald 

 control. For Mcintosh and Cortland, however, instead 

 of reducing scald, warming clearly increased it. We 

 have not seen this result in previous tests. The fact that 

 all three cultivars were produced in the same orchard, 

 harvested on the sameday, treated simultaneously, and 

 stored in the same room shows that response to warm- 

 ing can be very different among cultivars. We believe 

 that the opposite results seen here among cultivars are 

 related to the fact that Mcintosh and Cortland produce 

 much more ethylene than Delicious, and ethylene has 

 complex effects on scald development. 



These findings illustrate the risk involved in at- 

 tempting to use a non-chemical scald-control proce- 

 dure. Under the conditions of this experiment, using the 

 predictive curve to determine when to rely on warming 

 for scald control would have been a resounding success 

 for Delicious. However, the predictive curve was not 

 adequate for Cortiand, and warming was never effec- 

 tive on Cortiand or Mcintosh. 



Whether or not warming is a suitable scald control 

 procedure is not yet clear. Noticeable ripening can 

 occur during warming, and it would entail major logis- 

 tical problems to change fruit temperatures. However, 

 the objective of this study was to use warming as an 

 example of a non-chemical procedure applied in con- 

 junction with scald prediction, and from this viewpoint 

 it can be seen that at this point in time, it's a very risky 

 approach, one that we caimot recommend. 



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Fruit Notes, Fall, 1994 



