5 - 



Table 1, 



Effect of varying levels of K 

 on Ca accumulation. 



1 n 



Delicious' apple leaves 



Percent dry weight basis 



Means in the same column followed by different letters are signifi- 

 cantly different at the 5% level. 



The data in Table 1 show that there were differences in leaf K 

 among all three K levels in 1960 through 1963, but only the highest 

 level (2.07, 1.91. 2.21 and 1.96%) significantly decreased the accum- 

 ulation of Ca in the foliage. It is doubtful that K levels of 1.90% 

 or more are common in 'Delicious' trees in grower orchards or that 

 high K levels have been a major factor in the increased incidence 

 of cork spot and bitter pit in 'Delicious' apples in our orchards. 

 The Ca levels in Table 1 are much below the 1.5% or higher optimum 

 level established by some states for Ca. However, as shown in the 

 Pomological Paragraph that follows, low Ca levels have been and con- 

 tinue to be common occurrence in Massachusetts. 



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



POMOLOGICAL PARAGRAPH 



Low aaloium (Ca) levels have prevailed for many years: When the 

 leaf analysis service for apple growers was initiated in 1956, we 

 established for the major elements what was considered to be the 

 desirable mineral content of leaves from bearing 'Mcintosh' apple 

 trees. For leaf Ca, 0.90-1.40% per weight was suggested as being 

 optimum. Since 1956, leaf Ca has been consistently low in our 

 'Mcintosh' apple trees (Table 1), but we paid little attention to 

 this element except for stressing the need of lime. 



Table 1. Ca content of 'Mcintosh' 

 dry weight, from growers 



apple leaves 

 orchards . 



expressed as % 



Year 



1956 

 1957 

 1958 

 1959 

 1960 

 1961 



Avg. % Ca 



80 

 92 

 82 

 95 

 89 

 89 



Range in % Ca 



61 

 61 

 49 

 62 

 37 

 50 



1.04 

 1.33 

 1.52 

 1.90 

 1.60 

 1.46 



