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SUHGESTIONS FOR USE OF CALCIUM SPRAYS IN 1983 



Mack Drake and William J. Bramlage 

 Department of Plant and Soil Sciences 



Calcium chloride fCaCl-,) foliar sprays are recommended in 

 Massachusetts for all apple growers to increase the flesh calcium 

 (Ca) content. Higher flesh Ca can markedly reduce bitter pit, 

 cork spot and fruit breakdown during storage. 



Apply foliar sprays of CaCl2, beginning 3 weeks after petal 

 fall and repeat at 2 week intervals totaling 6 to 8 applications. 

 Apply 6 pounds CaCl2 per acre per spray until mid-July. After mid- 

 July apply 8-10 pounds per acre per spray. Continue foliar CaCl2 

 until fruit are ready for harvest. Use a technical grade of CaCi-;, 

 such as Allied Chemical Dow Plake, 77-801 CaCl^. Other brands may 

 be equally suitable. 



Experience in Massachusetts has shown that CaCl^ can be com- 

 bined with pesticide sprays. However, some growers nave observed 

 that the combination of Captan or Guthion (azinphos methyl) 50 WP 

 and CaCl^ may increase foliar burn. DO NOT MIX CaCl^ AND SOLUBOR 

 SPRAYS! ALWAYS DISSOLVE CaCl2 IN A PAIL OF WATER and add this 

 last, when the spray tank is nearly full, to insure that the CaCl2 

 is completely dissolved before spraying begins. 



Foliar CaCl2 sprays may be applied as dilute (300 gallons/acre) 

 or up to lOX concentration (30 gallons/acre). In our research, 

 apple flesh Ca was increased more by concentrated than by dilute 

 sprays . 



CaCl2 sprays can cause burn of leaf margins. Foliar injury 

 has been more serious on Mcintosh than on Delicious or Cortland. 

 Apple leaves are less susceptible to CaCl-, burn after mid-July. 

 Mcintosh growing on M7 may be more susceptible to foliar burn than 

 those on standard rootstock. Weak or injured trees may be more 

 susceptible to CaCl^ burn than healthv trees" To reduce the chance 

 of leaf burn, DO NOT REPEAT A FOLIAR CaCl^ SPRAY UNLESS ONE-HALF TO 

 ONE INCH OF RAIN HAS FALLEN SINCE THE LAST APPLICATION'.' 



In 1982, 3 different materials were compared as suppliers of 

 foliar Ca at the University of Massachusetts Horticultural Research 

 Center. One was commercial CaCl^; the second was a proprietary 

 formulation of CaCl^; and the thnrd was a chelated Ca compound. 

 Rate of application^was 86 grams Ca per tree in a total of 8 appli- 

 cations. Fruit Ca was 115, 165, 155 and 158 parts per million 

 respectively, for control, CaCl2, Formulation 1 and Formulation 2; 

 the amount of the breakdown was 33, 7, 7 and 11 percent, respectively, 

 for fruit air stored at 32°F for 5 months and then held at 74°F for 

 7 days. These results agree with those of previous years, and show 



