probably the use of the antioxidant chemicals 

 diphenylamine (DPA) and ethoxyquin. In the mid- 

 1950's Smock (4) found that these materials 

 provided excellent control of scald, and following 

 their approval by the Food and Drug 

 Administration they became standard commercial 

 treatments as postharvest dips for fruit destined 

 for long-term storage. These materials interfere 

 with the oxidation of alpha farnesene to 

 conjugated trienes, as does low O2 in a CA 

 atmosphere. 



Use of antioxidants is not without its 

 problems. The materials must be used with care, 

 since excessive dosage can cause severe fruit 

 injury. Even use at recommended dosage often 

 leads to injury due to entrapment of solution in 

 cavities, between fruit, or in wooden containers. 

 As this trapped solution evaporates, the 

 antioxidant concentrates to injurious levels. 

 There is also concern about the risks to 

 consumers from residual antioxidants; since these 

 materials are volatile, little or no residue should 

 persist at the end of storage if the material is 

 used properly. However, these materials have not 

 been approved in some countries, so treated fruit 

 cannot be exported to such countries. 



Current directions . During the past 3 years 

 we have been conducting extensive studies on 

 scald. Our goal is to reduce dependence on the 

 antioxidant chemicals for control. Current 



recommendations are generally based on a "worse- 

 case scenario," since growers simply cannot risk 

 scald development. However, as is described 

 above scald susceptibility is extremely variable 

 and maximum treatment is often (usually?) not 

 necessary. If we can better quantify the factors 

 affecting scald, we should be able to quantify the 

 potential for scald and adjust the recommended 

 treatment to the actual need. One approach to 

 this is through careful collection of climatological 

 data in relation to scald development. A 

 cooperative study involving a number of fruit 

 researchers and directed by Dr. David Blanpied at 

 Cornell University is in progress. We are 



attempting a different approach: a search for a 

 chemical index of scald susceptibiUty in the fruit 

 that might signal the need (or lack thereof) for 

 chemical treatments at the time of harvest. 



Scald was probably the single most 

 important postharvest problem for apples until 

 antioxidant chemicals were approved. For 20 

 years after approval little further attention was 

 given to this problem. Now interest is renewed, 

 largely due to the need to reduce the use of 

 chemicals wherever possible. Growers can expect 

 to hear much more about scald control measures 

 in coming years. 



Literature Cited 



1. Dover, C. J. 1985. Commercial scale 

 catalytic oxidation of ethylene as applied to 

 fruit stores. In: J. A. Roberts and G. A. 

 Tucker (eds.). Ethylene and Plant 

 Development. Butterworths, London. pp. 

 373-383. 



2. Fidler, J. C. 1956. Scald and weather. 

 Food Sci. Abstracts 28:545-554. 



3. Merritt, R. H., W. C. StUes, A. V. Havens, 

 and L. A. Mitterling. 1%1. Effects of 

 preharvest Jiir temperatures on storage scald 

 of Stayman apples. Proc. Amer. Soc. Hort. 

 Sci. 78:24-34. 



4. Smock, R. M. 1957. A comparison of 

 treatments for control of the apple scald 

 disease. Proc. Amer. Soc. Hort. Sci. 69:91- 

 100. 



5. Wilkinson, B. G. and J. C. Fidler. 1973. 

 Physiological disorders. In: Fidler, J. C, B. 

 G. Wilkinson, K. L. Edney, and R. O. 

 Sharpies (eds.). Tlie Biology of Apple and 

 Pear Storage. Commonwealth Agricultural 

 Bureaux, East Mailing, Kent, England, pp. 

 67-Dl. 



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