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APPLE COVER SPRAYS UNAFFECTED BY THE ADDITION OF CALCIUM CHLORIDE* 



George M. Greene, Larry A. Hull, and Kenneth D. Hickey 

 Pennsylvania State University 



From a fruit quality standpoint, it has been proven that calcium 

 chloride (CaCl2) can reduce corking and bitter pit and can lengthen the 

 storage life of apples. Research conducted under the CIPM apple subproject 

 hi 

 di 

 eqi 



cides arid CaCl2 can be safely combined, eliminating the necessity for 

 making s?parate applications. 



storage life of apples. Research conducted under the CIPM apple subproject 

 las proven that the addition of CaCl2 to pesticides sprays normally used 

 iuring the post-bloom period results in disease, insect, and mite control 

 ?qual to that obtained when the pesticides are applied alone. Thus, pesti- 



Apple growers the world over are plagued by low calcium physiological 

 disorders of fruit. These disorders can appear during the growing season or 

 they may develop during the postharvest storage period. CaCl2 can often 

 effectively reduce the level of these disorders. Therefore, recommendations 

 have been developed to apply various rates of CaCl2 depending on the apple 

 variety and disorder involved. Since CaCl2 is considered a fertilizer, EPA 

 approval is not required for its use. Apple growers have been tank mixing 

 it with the commonly used apple pesticide cover sprays to reduce the cost of 

 appl ication. 



However, recent concerns about pesticide efficacy, including suspected 

 resistance, have questioned the advisability of the past tank mixing prac- 

 tices. First, concerns have centered around the spray solution pH. 

 According to the manufacturers of CaCl2 the pH of concentrations like those 

 commonly encountered can be as high as 10.3 and alkaline conditions may 

 reduce pesticide efficacy. Second, since CaCl2 is hygroscopic, concern has 

 been raised concerning the weatherabil ity of sprays containing CaCl2. 



Extensive field experiments were conducted during 1980, 1981, and 1982 

 to test the efficacy of tank mixed pesticide combinations with various rates 

 of CaCl2. Results are given in Table 1. Details have been provided on the 

 pesticides investigated, the CaCl2 rates used, and the pests that have been 

 studied. Some of the pests were evaluated on apple leaves while others were 

 observed on the fruits themselves. Results have been very consistent for 

 all pests, pesticides, CaCl2 rates, and for all three years. Almost without 

 exception, the control of pests was the same regardless of whether the 

 pesticides were applied alone or in combination with 24, 48, or 72 pounds of 

 77 to 80 % CaCl2 per acre per year. Under Pennsylvania conditions, 24 

 Ibs/acre/year have given good control of corking and bitter pit which deve- 

 lop during the growing season. However, in Massachusetts, upward of 72 

 Ibs/acre/year are recommended to control internal breakdown of Mcintosh. 



•Reprfffted wifh permission ot the authors from "Consortium tor integrated 

 Pest Management Success Stories," Pennsylvania State University, 1983. 



