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The drought in the siaimner and fall o£ 1976 markedly affected 

 Michigan's 1976 apple crop. In a niimber of orchards fruit did not 

 mature uniformly on the trees suffering from severe moisture stress, 

 with those around the periphery of the tree ripening earlier than 

 fruit in the interior of the tree. This phenomenon was not as 

 pronounced in irrigated orchards. 



Harvest 



Market demands for larger, redder apples increases the hazard 

 of internal breakdown of Jonathan fruit. Control of internal 

 breakdown is now achieved by a pre-storage water dip or drench 

 treatment with a 4^ calciiun chloride solution. Unfortunately, 

 calcium chloride is corrosive to most metals; thus, application 

 equipment must be cleaned after use. Corrosion of nails or other 

 bin fasteners also can be a problem. A fungicide is added to the 

 calcium chloride solution to control storage rots. The solution 

 can be utilized until it becomes excessively contaminated with 

 accumulated soil or debris. 



For many years, Michigan growers obtained adequate scald con- 

 trol on stored fruit by using DPA at 1000 ppm. In recent years, 

 it has been necessary to increase the rate to 2000 ppm except for 

 Jonathan, Idared and late-picked Rome Beauty, for which 1000 ppm 

 appears to give adequate scald control. 



Storage scald is controlled best when fruit is treated at nor- 

 mal orchard temperatures within a day or so after harvest. Cold 

 fruit directly from the orchard or from storage for up to 2 weeks 

 after harvest can be effectively treated for scald control but the 

 maximum concentration of DPA must be applied. The chemical becomes 

 less effective as the treatment is delayed but it is better to make 

 a late application of the material to apples intended for long term 

 storage than not to treat at all. A fungicide, either thiabendazole 

 (TBZ) or benomyl, is added to the scald inhibitor solution to pre- 

 vent widespread development of blue mold, soft rot and gray mold 

 diseases on apples during subsequent storage and handling. 



Ethylene is a gaseous plant hormone that causes fruits to 

 ripen. It is produced at a constant low rate during the last few 

 weeks of growth and development of immature fruit. The ethylene 

 production rate abruptly increases immediately preceding the onset 

 of ripening, causing the internal atmosphere ethylene concentration 

 to increase from about 0.1 ppm to 10 to 100 ppm over the course of 

 several days. 



Dr. D.R. Dilley has developed a colorimetric technique that 

 enables storage operators to detect high ethylene levels in fruits 

 as they begin to ripen. About 20 fruits are placed in a 10 liter 

 dessicator, which is then filled with water. A vacuum is applied 

 for about 5 minutes to withdraw gas from within the fruit. A sam- 



