SCALD CONTROL METHODS FOR 1962 



The approach to scald control which one uses is complicated by quite a few 

 factors. From the data we and others have obtained in the past 5 or 6 years, it 

 is now very apparent that we not only have to consider the variety and the scald 

 control materials, Ethoxyquin (Stop Scald) and diphenylamine (DPA) , but also 

 whether each variety is to be stored in regular or CA storage, how long it is to 

 be stored, fruit maturity, period of time from harvest to storage, temperature of 

 the fruit in storage. In addition, it appears that there may be significant 

 differences in scald susceptibility among strains of a variety as well as between 

 varieties. Thus it appears that even with the availability of scald reducing 

 chemicals the blanket use of one or both of these chemicals on all stored apple 

 varieties is not advisable. In addition, neither Stop Scald nor DPA are so 

 reliable that their use means that good scald control Is a certainty on some 

 varieties in any year or on other varieties in those years when scald is a very 

 serious problem. 



The Present Situation With Stop Scald and DPA 



Stop Scald : This material has been coimnercially available for 2 years and should 

 be used at the rate of 3 pints per 100 gallons when applied as a tree spray or 

 post-harvest dip, flood or spray. If used as a spray it should be applied within 

 36 hours of harvest. Unfortunately, apples given preharvest sprays of Stop Scald 

 are apt to show dark-ring residue spots and in some cases preharvest sprays are 

 less effective than post-harvest treatments. Also, Stop Scald is generally less 

 effective in controlling scald on some varieties than DPA. Stop Scald's chief 

 advantage over DPA is that it is not apt to cause injury to fruit that are box or 

 bin flooded or dipped. This material appears to have no appreciable ripening 

 action on apples. The residue tolerance for this material is 3 ppm. Do not apply 

 to fruit more than once. Allow fruit to drain reasonably well after treatment. 

 Be sure that the entire fruit surface is covered with the solution. A post- 

 harvest solution of 100 gallons can be expected to treat about 1000 bushels of 

 fruit. Make up fresh solutions each day. Keep all solutions well agitated. A 

 diagram of a post-harvest "cascade" type application for Stop Scald is available 

 upon request. All fruit treated after harvest must be labeled on their shipping 

 containers, "Ethoxyquin treated to retard spoilage". The lettering must be aa 

 large as other grade labels. 



DPA : This material has been cleared for use this fall and may be applied before 

 or after harvest. It will be sold as an 837o wettable powder and should be used 

 at the rate of 2 pounds per 100 gallons of water (2000 ppm.) on most varieties. 

 The residue tolerance is 10 ppm. Since this is the first year of commercial 

 availability, we suggest that it be used on trial basis. DPA appears to be gen- 

 erally more effective for scald control than any known chemical method on most 

 varieties. Tree sprays are nearly as effective as post-harvest treatments. Tree 

 spray applications must be applied within 36 hours of harvest and thorough 

 coverage of the fruit surface must be obtained. Do not use tree sprays when 

 temperatures are 80°F or higher. With post-harvest applications use the same 

 methods as mentioned with Stop Scald except that better drainage of excess DPA 

 liquid is required. This means that apples in bins or crates may be injured 

 where excess DPA liquid collects and stays around fruit in the bottoms of such 

 containers when fruit is flooded, sprayed, or dipped. Repeat applications are not 

 possible with DPA unless a heavy rain occurs between a tree application and 



