COMBINING CALCIUM CHLORIDE WITH PESTICIDE SPRAYS 



W.J. Bramlage, W.J. Lord, A.W. Rossi, and M. Drake 

 Department of Plant and Soil Sciences 



Growers have been using calcium chloride (CaCl2) sprays on 

 apple trees at IX and as separate applications for the past sever- 

 al years to reduce the severity of cork spot and bitter pit and to 

 increase the keepability of fruit in storage. A question unanswered 

 is the compatibility with other pesticides when used in the regular 

 spray program. Experience in Virginia indicates this to be a safe 

 practice, but we had no experience in Massachusetts. 



We initiated studies at the Horticultural Research Station in 

 1974 to accumulate information about CaClo compatibility with other 

 pesticides when used in a regular spray program. No foliar damage 

 occurred on Mcintosh and Delicious strains when we used 2 lbs of 

 CaClo per 100 gal at dilute (IX) concentration in the 5th through 

 the 8th cover sprays in 1974 (See Fruit Notes 40 (No . 1) : 5-6 , 1975). 

 However, the results of another study showed that this 2 lb-rate 

 of CaCl2 produced only a slight increase in fruit calcium (Ca) . 

 In 1975, we decided to increase the CaCl2 rate and to determine 

 whether it could be concentrated. Thus, CaCl2 was applied as 4 lbs 

 per 100 gal of water (IX) and as 24 lbs per 100 gal (6X concentrate) 

 starting with the 2nd cover spray in the schedule shown in Table 1. 



Some burn on the tip and edges of Mcintosh leaves was observed 

 after the 3rd cover spray, regardless of concentration. This damage 

 was considered excessive on Mcintosh strains when the CaCl2 was ap- 

 plied at 6X concentrate . The injury from sprays applied at IX 

 with a hydraulic sp rayer was not considered excessive and did not 

 increase witn tne 4 additional sprays of the same concentration. 

 Furthermore, in a separate experiment in which the IX spray of CaCl- 

 v>/as applied with a "speed-sprayer" little or no injury occurred on 

 Mcintosh leaves. However, it must be noted that 6 inches of rain 

 fell between the 4th and 5th cover spray, 2.5 inches fell between 

 the 5th and 6th cover spray, and 3.0 inches fell between the 6th 

 and 7th cover spray. Without this rainfall, the injury might have 

 been more severe . Clearly, at 4 lbs CaCl2 per 100 gal there is 

 potential for foliar injury to Mcintosh, and this potential is much 

 greater when the spray is applied as a concentrate. 



Was the CaCl2 spray beneficial? In a separate experiment, we 

 found that 7 sprays of CaCl- (IX) at 4 lbs per 100 gal increased 

 the Ca level in fruit 501. Assessment of the value of this increase 

 in improving storage life of the fruit is still incomplete, but to 

 date we have found that the 50% increase in fruit Ca virtually elim- 

 inated bitterpit and internal breakdown after regular storage to 

 January. Thus, it appears that repeated application of 4 lbs per 

 100 gal of CaCl2 has the potential for substantially improving stor- 



