preferable to use high-calcium lime. In 

 the past, it was common to apply lime 

 once every three years, needed or not. 

 Recently, more frequent application is 

 recommended on an as-prescribed basis. 

 The proper pH maintains the availabil- 

 ity of many of the nutrients that peach 

 trees require. Therefore, proper pH, and 

 periodic soil analyses are important to 

 your nutrient-management program. 



In general, your soil test should show 

 pH or the amount of lime required to 

 reach a specific pH, and the amounts of 

 nitrogen (N), phosphorus (P), potassium (K), 

 calcium (Ca), and magnesium (Mg). These 

 levels should all be high to very high, except for 

 P. We normally are not concerned with P 

 unless the level is very low. P is applied prior to 

 planting, if needed, and then basically ignored. 

 Leaf-tissue analysis fine-tunes this informa- 

 tion and accurately determines the levels of 

 these elements in the plants themselves. 



Leaf-tissue Analysis 



For fruit trees, leaf-tissue analysis is the 

 best method for determining nutrient needs. 

 Table 2 gives the results of a typical leaf-tissue 

 analysis. The next step is to compare these 

 actual test results with standards that have 

 been developed for peaches (Table 3). The ones 

 we use were developed by Cornell University. 

 Boron is a controversial element with peaches. 

 The standard recommendation has been to 

 apply five pounds of borax per ton of fertilizer 

 before planting. More recent recommendations 

 are to apply a small amount of boron 

 periodically. The nutrient management 

 program for each tree or block of trees can now 

 be developed based on soil and tissue test 

 results that are presented here and other 

 factors that may be present in this test site. 



A general rule of thumb is to increase/ 

 decrease the past rate of each nutrient by 10% 

 for each 0.1 variation from the standards given 

 for that element. For example, the N level in 

 our sample is 2.30%. It should be between 3.0 

 and 3.5%. Therefore, the rate of N applied the 

 year of application that these tests will be based 



Table 2. A typical leaf analysis result. 



Element 



Results 



(%) 



Element 



Result 

 (ppm) 



Nitrogen (N) 2.30 



Phosphorus (P) 0.25 

 Potassium (K) 1.25 

 Calcium (Ca) 1.35 



Magnesium (Mg) 0.45 



Zinc (Zn) 22 



Copper (Cu) 4 



Manganese (Mn) 27 

 Iron (Fe) 47 



Boron (B) 54 



Table 3. Leaf tissue standards for peach 

 leaves.* 



Element 



Short Optimum Excess 



Nitrogen 3.00 3.00-3.50 3.7 



Potassium 1.25 1.50-2.50 2.50 



Calcium 1.35 1.35-1.50 ? 



Magnesium 0.25 0.35-0.50 0.50 

 Boron 



Copper (ppm) 5 7-10 10 



Manganese (ppm) 25 90-110 110 



Zinc (ppm) 15 25-50 50 



* SHORT: usually requires corrective 



measures; deficiency symptoms should be 

 seen. OPTIMUM: the nutrient-manage- 

 ment program currently in use is adequate 

 to maintain nutrient levels required for 

 current tree and crop-load conditions. 

 EXCESS: amount of nutrient applied 

 should be reduced or eliminated until future 

 leaf-analyses indicate otherwise. 



on should be at least 70% higher than that of 

 the previous year. The harder decision to make 

 is if the test results were 0.7 higher (4.2) rather 

 than lower than the standard level. For apples, 

 it commonly takes several years for N levels to 

 decrease where test results have shown them to 

 be very high. It may be wise to eliminate N in 

 fertilizer applications for at least one year if the 

 tissue tests show N levels to be 50% or more 

 above recommended levels. These decisions 

 also can be further complicated when 



Fruit Notes, Volume 61 (Number 4), Fall, 1996 



11 



