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CaCl2 dips have the potential for marked reductions of storage prob- 

 lems in Northeastern apples, but we still need to conduct more exten- 

 sive tests to accurately measure their usefulness. 



Commercial use of postharvest CaCl^ dips is rapidly occurring 

 in many parts of the world, but not without problems. The CaCl^ 

 solutions are corrosive and may shorten the "life" of storage equip- 

 ment and bins. Furthermore, while we detected no injury to 'Mcin- 

 tosh' and 'Baldwin', and only very slight injury (flecks of calyx- 

 end burn on a few fruit) to 'Cortland', it is known that serious 

 damage can occur. Our tests should help considerably in understand- 

 ing how to optimize the use of postharvest dips and minimize these 

 problems of corrosion and possible injury to the fruit. The prin- 

 ciples involved seem to be simple: 



1. Natural openings (holes) must exist in the apple surface 

 for Ca entry. The more holes (open lenticels, open calyx, 

 etc.) there are, the more Ca will be absorbed from a treat- 

 ment . 



2. Absorption is almost entirely from residue following the 

 dip. The only role of the dip is to produce a residue 

 (which, incidentally, is not considered harmful to con- 

 sumers) , and normal variables of dip conditions seem to 

 have no influence on this residue. 



3. The humidity in the storage is a factor to be carefully con- 

 sidered. If a storage is maintained at 95°o R.H. , as is 

 usually recommended, dips will probably be more successful 

 than if the R.H. is lower, because absorption will continue 

 over a long period of time -- as long as the residue re- 

 mains liquid. 



4. The key factor is the concentration of CaCl2 used in the 

 dip solution. Different varieties and different conditions 

 will produce different amounts of Ca absorbed into the 

 apple flesh from a given CaCl2 concentration. Use of 41 

 CaCl2 (32 lbs/100 gal) can probably be expected to produce 

 significant gains in Ca under a wide range of conditions, 

 but 1.51 or 1% (12 or 16 lbs/100 gal) CaCl2 is probably 

 sufficient under many conditions. 



If treatment is employed judiciously, it is probably not nec- 

 essary to use the very high CaCl2 concentrations (24-32 lbs/100 gal) , 

 and therefore, potential problems can be minimized. Several Massa- 

 chusetts growers who tested CaCl^ dips on small lots of 'Mcintosh' 

 and 'Cortland' apples in 1975 incurred no problems and were pleased 

 with the results. We hope that considerably more experience will 

 be obtained this year so that this promising approach to improved 

 storageability of apples will be more clearly understood and more 

 widely applicable. 



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