apple leaf and fruit analysis of 9 trees on August 17 and on October 1, 

 and found over a 50% reduction in fruit calcium, and a 30% gain in leaf 

 calcium by October 1. They reasoned that leaf calcium was increasing 

 at the expense of fruit calcium and proposed late summer foliar calcium 

 applications. Competition by the leaf with the apple fruit for calcium 

 has been suggested as one reason for greater incidence of bitter pit 

 with a small crop, since in these light crop years, there is relatively 

 greater shoot and leaf development. 



Reduction of Bitter Fit 



Incidence of bitter pit has been reduced greatly by the foliar ap- 

 plication of calcium solutions on trees with a history of producing pit- 

 ted fruit. Garman and Mathis , in Connecticut, U.S.A., Ginsburg and Bey- 

 ers, in South Africa, Jackson, and Kidson and coworkers in New Zealand, 

 Martin, et al in Australia, Yamazaki et al in Japan, and Smock and others 

 have made major research contributions in this area. In South Africa, 

 Ginsburg and Beyers reported that 3 spray applications of 1 per cent 

 solution of calcium nitrate (8 pounds/100 gal. water) , beginning about 

 2 weeks after bloom and repeated at 2 week intervals , reduced bitter 

 pit from 20 to 2 per cent. 



Solutions of either calcium nitrate or calcium chloride have been 

 effective in reducing bitter pit. The Japanese have demonstrated that 

 incidence of bitter pit was increased by nitrogen. Thus, in theory, 

 calcium nitrate, by supplying foliar nitrogen, would be somewhat less 

 effective than calcium chloride in reducing bitter pit. However, obser- 

 vations by Dillon in Australia, at the Massachusetts Experiment Station 

 and elsewhere, indicate that the use of calcium chloride is more likely 

 to result in injury to the leaf margin or leaf scorch. When foliar ap- 

 plications of calcium nitrate are used, corresponding reductions in fer- 

 tilizer nitrogen applications should be scheduled. 



Growers who are interested in applying calcium foliar sprays may 

 obtain recommendations from Dr. W. J. Lord, Extension Pomologist, Uni- 

 versity of Massachusetts, Amherst, Mass. 



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POMOLOGICAL PARAGRAPH 



Sources of Nitrogen - In the 93rd Annual Report of the State Horticul- 

 tural Society of Michigan, A. L. Kenworthy stated that recent research 

 has shown that there are no obvious differences in the effect of vari- 

 ous nitrogen sources on fruit trees. This gives support to our state- 

 ment that it is the amount of actual nitrogen applied that is important 

 and not the source, therefore, the selection should be based on cost. 



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