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under the trees. Eliminating grass competition by herbi- 

 cides reduces the rate o£ N applications required by 

 approximately 30 to 40 pounds per acre per year. Ex- 

 cessive tree vigor resulting from excessive N applications 

 can be partially compensated for by late summer pruning. 

 This has two main effects: it improves fruit color by 

 improving light distribution, and tends to limit root 

 growth. Fruit size may also be reduced by summer pruning. 



P. Leaf concentrations of P may range from 0.08 to over 

 0.301. Mcintosh tends to accumulate less P than Delicious. 

 High levels of P in leaf samples indicate the possibility 

 that tree growth has been stunted by lack of N, drought, 

 competition from grass, root and/or trunk injuries, or 

 because of other nutrient deficiencies. 



K. Optimum K levels usually fall between 1.2 and LSI. 

 Varieties such as Delicious appear to be more efficient 

 in taking up K than others such as Mcintosh. K levels 

 should be considered in relation to N levels, with N/K 

 ratios of 1.25 to 1.50 indicating reasonable balance. 

 Levels below 1.2% indicate possible need for additional 

 application of K; those below 0.8% indicate deficiency. 

 The form of K applied should be related to Mg levels. 

 If both K and Mg are needed, sulpomag should be applied, 

 v\fhile if Mg is adequate the use of muriate of potash or 

 other forms may be appropriate. 



Ca . Ca levels below approximately 1.24% should be con- 

 sidered as low, those below 1.00% as deficient. Low levels 

 of Ca may indicate insufficient soil levels of Ca (parti- 

 cularly as indicated by the subsoil), and/or low pH , 

 but may be the result of shortages of other elements such 

 as N or boron (B) or of other factors that limit the 

 ability of the tree to absorb and translocate Ca. Leaf 

 Ca levels normally show a direct positive relationship 

 with leaf N concentrations. Liming and correcting soil 

 pH should be the first step in dealing with low Ca levels. 

 If additional corrective treatments are required these 

 might include soil applications of calcium sulfate (gypsum) 

 if pK is too high, and/or foliar applications of calcium 

 chloride. Fruit content of Ca has been related to keeping 

 quality. Large fruit usually contains lower concentrations 

 of calcium. Foliar sprays and/or post-harvest application 

 of CaCl2 may be needed on such fruit. 



Mg . Optimum levels of Mg fall in the range of 0.30 to 0.45%. 

 ^Rapidly growing young trees and trees bearing heavy crops 

 of fruit are most susceptible to Mg deficiency. Low Mg 

 supply in the soil is the major limiting factor. High-Mg 

 dolomitic lime and applications of Mg salts such as kieserite 

 or langbeinite (sulpomag) are usually required to overcome 



