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POMOLOGICAL RESEARCH 

 8, The Nutrition of Apple Txees 



In 19U8, the project entitled "The Nutrition of Apple Trees" was ■;■ 

 initiated. The loajor objective of this project vras to determine the 

 kinds and amounts of fertilizer v/hich are required to produce vigorous 

 heelthy trees capable of producing maximum yields of high quality fruit. 



In conducting the project a nev/ approach was made in determining the 

 effectiveness of the different fertilizer treatments. The actual amounts 

 of the different mineral elements found in the leaves were determined by 

 chemical analyses, •'•he chemical composition of the foliage wcs used to 

 determine the effectiveness of the several fertilizer treatments and to 

 study the relation of the treatments to tree performance, quality of fruit, 

 and to determine deficiencies and excesses* V/hile it is not possible in 

 an article of this nature to discuss all the results of the project, some 

 of the important findings may be mentioned at this time. 



The results clearly demonstrated the need for considering elements 

 other than nitrogen in developing a fertilizer program. The need for applying 

 adequate amounts of potassium was first established by leaf analysis and 

 and then by tree performance and fruit quality. It ivas found that high 

 rates of nitrogen fertilization increased the potassium requirements of 

 the tree, and if these requirements were not met the appearance of potassium 

 deficiency was hastened. 



Fruit color was found to be associated vfith both the nitrogen and the 

 potassium levels found in the foliage. The poorest colored fruit was pro- 

 duced by trees which were high in nitrogen and low -in potassium. Fruit of 

 high color was produced by trees vTith medium levels of nitrogen and high 

 levels of potassium. 



Fruit from high nitrogen trees was considerably softer than those from 

 medium nitrogen trees and -had a 'shorter storage life. High rates of nitrogen 

 fertilization gave somewhat increased yields and tree growth but when the 

 color and quality of the fruit was taken into consideration the increase 

 yields became of questionable value. Annual production was not maintained 

 by high rates of nitrogen and it was only vfhen crop size was controlled 

 by chemical thinning that trees were made annual, 



i'iagnesium requirements were taken care of if adequate amounts of high 

 magnesium v/ere applied to the soil. 



Since this experiment vias conducted vfith ilclntosh, the results apply 

 most specifically to that variety. Although most of the results can be 

 applied in a general vray to other varieties, we believe they must be modified 

 to meet specific requirements of each variety. In order to determine if 

 other varieties have different nutritional requirements, we are initiating 

 a nutritional project along similar lines vdth Delicious, 



— »W. D. Weeks 

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