CHAPTER 



I I Control of Nitrogen Ef- 

 fects on Mcintosh Apple 

 Trees in New York* 



DAMON BOYNTON 



I 



t has been recogkized for many years that nitrogen is 

 more apt to limit the productivity of apple orchards under sod culture 

 than is any other nutrient. It has also been realized that apple trees 

 receiving heavy dosages of nitrogenous fertilizer may produce fruit of 

 markedly less desirable color and quality than trees receiving less 

 nitrogen. The Mcintosh apple, which is now the second most important 

 variety in the United States, is particularly responsive to nitrogen ferti- 

 lization, and shows both of these nitrogen effects to a marked degree. 



TREE RESPONSES TO NITROGEN FERTILIZATION 



An illustration of the average effects of three levels of spring nitrogen 

 fertilization on the yield and fruit color in a New York Mcintosh apple 

 orchard is given in Table I. In this orchard, total yield was significantly 

 increased by the nitrogen increment from 0.5 to 1.0 pound but not by 

 the increment from 1.0 to 1.5 pounds. The average percentage of the 

 fruit sample grading fancyf was significantly decreased, however, by 

 both increments of nitrogen. If it is assumed that the fruit sample from 

 the outside of the tree represents the entire tree and that the total yield 

 represents the yield of picked fruit, the product of the two should 

 indicate how much fancy fruit was produced by the trees under these 



*In the course of the work discussed I have had a good deal of help and en- 

 couragement from my colleagues and assistants in the Pomology Department at 

 Cornell University. In particular, I am indebted to Drs. A. I. Heinicke, M. B. 

 Hoffman, R. M. Smock, and E. G. Fisher of the department, and to three grad- 

 uate students, J. A. Cook, Richard Harris, and O. C. Compton. 

 fFruits with half or more of their surfaces colored red. 



