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Calc2 may be combined with scald inhibitors and fungicides in the post-harvest 

 treatment solution. Cornell University has recommended the following mixture for 

 postharvest treatment of Mcintosh: 



21 lbs of CaCl2 per 100 gallons of water 



1/2 lb of Benlate or 16 fluid ounces of Mertect 



1 lb of Captan 



1000 - 2000 ppm DPA 



We suggest that 1/2 quart of vinegar also be added 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. 



In use of postharvest CaCl2 drenches or dips, it is important to understand that 

 little or no Ca enters the fruit during the treatment. The purpose of the drench is 

 to leave a residue of CaCl2 on the fruit. Ca is slowly absorbed by the apple from 

 the residue during storage. Therefore, the drench is never followed by a rinse, which 

 would remove the residue. Furthermore, for Ca to be absorbed from the residue, the 

 residue must not dry out. However, if the storage is operated at lesss than 90% relative 

 humidity the residue may dry out and no Ca uptake will occur as a result of the drench 

 treatment. 



We have encountered no difficulty from this residue when apples are removed from 

 storage. It will be removed if apples are water-dumped, but even with hand-packed 

 fruit no difficulty has been reported. 



CaCl2 drenches can cause fruit injury, which occurs as tiny black spots on the surface 

 of the fruit. Generally, these spots are concentrated in the calyx cup of the apple 

 and are not objectionable, although under some circumstances they may coalesce into 

 more unsightly blotches or may occur at the lenticels on the cheeks. Do not exceed 

 the recommended CaCl2 concentration, as risk of this injury escalates rapidly at higher 

 concentrations. 



CaCl2 is also corrosive, so equipment should be thoroughly cleaned at completion 

 of treatment. However, with appropriate rinsing corrosion should not be a concern. 



The purpose of the postharvest application of CaCl2 is to reduce the risk of 

 breakdown, rot, and scald during but especially after storage. The recommended 

 treatment will not make fruit firmer, but will improve their ability to hold up during 

 marketing. Treatments will be of greatest benefit to mature fruit destined for long-term 

 storage. Overripe fruit cannot be expected to benefit significantly from a CaCl2 

 treatment. 



MAGNESIUM (Mg) 



Mg deficiency is closely associated with very acid soils. The pH in most orchards 

 is higher than 25-years ago because liming programs and the change from sulfur to 

 organic fungicides; thus, Mg deficiency is now not common. 



Dolomitic lime (high Mg lime) is the least expensive source of Mg for orchards. 

 It can be applied anytime during the year. If the Mg level in leaves is below 0.25% 

 apply 3 tons/A of dolomitic lime to maintain a soil pH of 6.0 - 6.5. If the Mg level 

 is below 0.20%, we also recommend 2 or 3 Epsom salt sprays at 15 to 20 lbs per 100 

 gallons dilute at approximately petal fall, first, and second cover. We suggest that 

 the Epsom salt sprays be applied as separate applications. However, pomologists in 

 other fruit growing areas in eastern United States believe that Epsom salts are 

 compatible with most pesticides up to 15X concentration. 



