-18- 



POSTHARVEST CALCIUM CHLORIDE TREATMENT 



William J. Bramlage 

 Department of Plant and Soil Sciences 



Our orchard surveys have shown that approximately one-third 

 of the commercial samples of Mcintosh apples in Massachusetts are 

 at such low calcium (Ca) concentrations that they possess a high 

 risk of developing breakdown after storage. Most other samples 

 contain Ca concentrations that carry a lower risk of breakdown, 

 but they could still benefit from some additional Ca. 



There are 2 feasible ways of successfully applying Ca to 

 apples: tree sprays and postharvest drenches. Even when a con- 

 scientious tree-spray program has been followed, apples can 

 usually still benefit from postharvest treatment. Thus, posthar- 

 vest Ca treatments have potentially wide benefit for the fruit 

 industry. 



A postharvest Ca application is viewed as a food-additive 

 process by the Food and Drug Administration. That agency has 

 stipulated that "Brining Grade" calcium chloride, containing 94% 



^^^^2, is acceptable for postharvest use. The technical flake 

 CaCl? commonly used for tree sprays is still acceptable for tree 

 sprays, but it may not be used for postharvest treatments . 

 There for e~| anyone wishing to use postharvest CaCl2 treatments 

 must obtain the Briner's Grade material, which is now readily 

 available from suppliers. 



CaCl2 may be combined with scald inhibitors and fungicides 

 in the postharvest treatment solution. Cornell University has 

 recommended the following mixture for postharvest treatment of 

 Mcintosh: 



21 lbs of CaCl2 per 100 gal of water 



h lb of Benlate* or 16 fluid ounces of Mertect* 



1 lb of Captan 



1000-2000 ppm DPA 

 We suggest that h quart of vinegar also be addded to this mixture 

 in 100 gallons of water. The vinegar neutralizes the CaCl2, 

 which otherwise makes the solution alkaline. There is evidence 

 that the alkaline solution may cause the fungicides to break down 

 rapidly in solution, and the addition of vinegar can protect 

 against their alkaline degradation. 



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