-22- 



This is not likely to occur if soil pH is properly maintained. 



Leaf Analysis 



Leaf analysis, with all of its faults, still represents the 

 best tool available for monitoring the nutritional status of 

 established trees. Some basic considerations must be kept in 

 mind : 



1. Method and time of sample collection should be uniform if 

 samples are to be compared. Specifying the sampling time, 

 i.e., 60 to 70 days after bloom, and location of leaves 



to be sampled is helpful in comparing results to standards. 



2. The leaf sample analysis indicates the amounts of various 

 elements in the sample as submitted. Leaf analysis does 

 not distinguish the amount of an element that is physio- 

 logically active from the amount that may be present as 

 contamination from various sources such as spray materials. 



3. Varieties, rootstocks, growth status and cropping levels, 

 as v/ell as soil variability and weather conditions during 

 the growing season, influence leaf contents of elements in 

 various ways and must be considered in interpreting leaf 

 analysis results. When growth is severely limited by 

 deficiency of some elements, the concentrations of all 

 elements including the deficient one(s) may appear to 



be normal. In such cases diagnosis of the actual cause 

 of the problem may require much additional information, 

 or even field trials of suspected elements. Some of these 

 types of relationships will be illustrated as individual 

 elements are considered. 



4. Leaf analysis can be used for various purposes such as 

 diagnosing possible causes of a problem, or, preferably, 

 to monitor nutrient status so that corrections can be made 

 before a problem becomes serious. In practice, both 

 approaches are usually involved. 



Leaf Analysis Standards for Apples 



1. N. Optimum N varies with variety and purpose for which it 

 is grown. Usually the optimum values fall within an over- 

 all range from 1.8 to 2.4%. Values below 1.81 N are usually 

 associated with reduced growth, smaller fruit size, and 

 greater tendency toward biennial bearing. Annual removal 

 of N by fruit is in the range of 30 to 40 lbs. per acre. 

 An additional 30 to 60 pounds may be required for tree 

 growth, to build reserves, and to support grass growth 



