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crease Ca in fruit by soil applications of this element. Not only 

 is there very poor absorption of Ca into apple trees, but also what 

 does enter moves slowly and much of it is immobilized in plant tis- 

 sue other than fruit. 



Radio-actively labeled calcium chloride was then applied to the 

 skin of 'Merton' apples at several stages of development. Applying 

 Ca to more developed rather than to very young fruits increased the 

 amount of Ca absorbed, so that mid- to late- summer sprays should 

 be more effective than early-summer sprays in controlling bitter 

 pit.. In addition, they found that more Ca was absorbed into the 

 calyx end than into the stem end region of a fruit, regardless of 

 its age. Therefore, the greatest absorption was into that portion 

 of the fruit that is lowest in Ca and most subject to bitter pit. 

 The authors stated that the lenticels (dots) on apples are an entry 

 site for Ca sprays and that lenticels are more numerous on the calyx 

 end than on the stem end of an apple. With more entry points at the 

 calyx end, direct application of Ca should be (and is known to be) 

 the most efficient way of increasing fruit Ca and reducing bitter 

 pit. 



In summary, the research by Lewis and Martin shows why tree 

 sprays may be more effective than soil applications for increasing 

 Ca content of apple fruits. Growers with bitter pit or cork spot 

 problems in their orchards may wish to use the control measure for 

 these disorders suggested in the article enclosed in this issue of 

 Fruit Notes entitled "Suggestions for Fertilization of Apple Trees 

 in 1974." 



*************** 



SUGGESTIONS FOR FERTILIZATION OF APPLE TREES IN 1974 



William J. Lord 

 Department of Plant and Soil Sciences 



Most apple orchards appear to have an abundance of fruit buds 

 which, with favorable weather, could produce an excessive crop in 

 1974. Therefore, your fertilizer program in 1974 should be direc- 

 ted toward the production of a medium-sized crop of high quality 

 fruit. 



Nitrogen (N) : To help accomplish the above goal, we believe that 

 N applications should be reduced by one-third to one-half in many 

 bearing blocks. Most Mcintosh trees had only a light crop in 1973 

 and these should have considerable reserve N available for utiliza- 

 tion this spring. Blocks of excessively vigorous trees probably 

 should receive no N. It is well to remember that it may take sever- 

 al years before an appreciable decrease in N level occurs on exces- 

 sively vigorous trees. 



