EFFECT OF NITROGEN AND POTASSIUM FERTILIZER ON 

 COLOR, RUSSET AND CORK SPOT OF GOLDEN DELICIOUS APPLES 



Mack Drake, John H. Baker, W.J. Lord 

 Department of Plant and Soil Sciences 



In a recent article, (Journal of the American Society for Hor- 

 ticultural Science 99:144-145, 1974) M.W. Williams and H.D. Billings- 

 ley reported effects of N fertilizer on yield, size and color of 



Golden Delicious apples grown in Washington. They found that 

 fruit color and quality of Golden Delicious apples was directly re- 

 lated to leaf N content. The correlation coefficient between leaf 

 nitrogen and extra fancy yellow fruit was -0.89, which means that 

 as N level increased, packout of extra fancy yellow fruit decreased. 

 When leaf-N was above 2.2%, the fruit tended to be large and green. 

 Trees with light green foliage, indicating low to intermediate leaf-N, 

 always produced yellow fruit. Maximum yields of high-quality fruit 

 were obtained when leaf-N levels were from 1.9 to 2.1%. 



Working cooperatively with Davis Orchard, Bolton, Massachusetts, 

 we are studying the effects of 3 levels of N and 3 levels of K fer- 

 tilizer on the color and russet condition of Golden Delicious apples. 

 During the past 5 years, levels of approximately 1.95, 2.10 and 2.20% 

 leaf-N have produced decreasing quantities of yellow fruit as leaf-N 

 has increased. This is in close agreement with the results reported 

 above by Williams and Billingsley. 



In addition, we have found that russet increased as leaf-N in- 

 creased, but decreased as leaf-K increased. The data in Table 1, 

 obtained in 1973, illustrate this relationship and are typical of 

 those for 1969-72. 



Effects of leaf-N and 

 1973. Davis Orchard, 



K on color and russet of Golden Delicious, 

 Bolton, Massachusetts. 



Leaf-N (%) 



Yellow color (%) 



Russet ( % ) 



2.00 

 2.15 

 2.20 



82 

 70 

 62 



63 

 67 

 86 



Leaf-K (%) 

 1.60 

 1.75 

 1.90 



74 

 70 

 69 



77 

 75 

 66 



Under Massachusetts conditions, we recommend that Golden Deli 

 cious be maintained in the range of 1.9 to 2.0% leaf N and 1.8% 

 leaf K. 



