-9- 



Reduce or omit N on young, vigorous Mcintosh trees when they start to bear fruit, 

 if the trees appear very vigorous, to avoid excessively large, poorly colored apples. 

 With this cultivar and all other cultivars, start participating in the Leaf Analysis 

 Program when the trees start to fruit in order to determine the fertilizer requirements 

 of the trees. (Information concerning the Leaf Analysis Program and specific details 

 on orchard fertilization can be obtained from your County Extension Service.) 



Bearing trees. There is no way to go broke faster than by producing high yields of 

 soft, green apples that bruise easily and keep poorly. On older, bearing Mcintosh trees, 

 N levels of 1.8 - 2.0% appear optimum. If the leaf analysis shows that the N level 

 is above 2.0%, adjust the fertilizer program according to tree vigor, productiveness 

 and fruit color, as experience indicates. High leaf N levels fall very slowly even when 

 no additional N fertilizer is supplied because large reserves of the element accumulates 

 in the soil, sod and tree. Therefore, it may take several years to bring an excess N 

 level down to the normal level. 



Our data shows that the total amount of N being applied is usually more important 

 concern to fruit quality than whether the N is supplied by applying ammonium nitrate, 

 sodium nitrate, calcium nitrate, etc. 



Fertilizer Placement Under Bearing Trees. The mass of the secondary root system 

 of apple trees lies between 2 and 3 feet in depth and within half the distance from 

 the tree trunk and its dripline. This explains why our studies show that more efficient 

 use of N and other elements can be obtained by application within a limited area closer 

 to the tree trunk rather than by application near the tree's dripline or a broadcast 

 application under the entire spread of the tree. Recent studies in England show that 

 under herbicide-strip management and with a wide in-row spacing, as in common in 

 Massachusetts, there was little N uptake from the grassed alley. 



POTASSIUM (K) 



Generally N is the only element required by non-bearing trees. However, experience 

 has shown that K is needed by non-bearing trees on land cleared from forests and on 

 sites with sandy or gravelly soil, or very acid soil. 



Not all horizons in the soil are equally able to supply nutrients to the tree. The 

 concentration of most elements are highest at the soil surface and decrease with 

 depth, but the rate of decrease differs between elements. For example, there is a 

 strong vertical difference in K status in soil, K being highest near the surface. 



Under drought conditions the permeability of the roots to water uptake decreases 

 very rapidly; reduction in water permeability reduces the uptake of all ions. In Massa- 

 chusetts we are particularly concerned about K and B deficiency and reduced fruit 

 size in drought years as was experienced during the summer of 1983. 



Total K absorbed and the total dry matter produced is similar for fruiting and non- 

 fruiting trees of the same size but in heavy-cropping trees K is translocated into the 

 fruits. Thus, the demand of a larger crop for K is great and both the tree and fruit 

 may be deficient in this element. 



