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NUTRITIONAL PROBLEMS IN 1978 AND SUGGESTIONS 

 FOR FERTILIZATION OF APPLE TREES IN 1979 



William J. Lord and Mack Drake 

 Department o£ Plant and Soil Sciences 



Prospects for a heavy bloom in 1979 are not too likely follow- 

 ing the large crop in 1978, However, there are ample flower buds 

 for a good crop in 1979 if weather is favorable at bloom. 



The analysis of leaf samples from commercial orchards showed 

 that potassium (K) and manganese (Mn) were deficient in some orchards 

 in 1978, and boron (B) was generally low. Foliar calcium (Ca) levels 

 were considerably higher than most years; nevertheless, bitter pit 

 on Cortland was very prevalent in some orchards and we were surprised 

 to find a serious amount of cork spot in some Red Delicious fruit, 

 and Empire. With the above observations in mind, we present the 

 following suggestions as a guide for fertilization in 1979, 



Nitrogen (N) : Most orchards had a large crop in 1979, there, 

 fore, the trees may be low in available N for utilization this 

 spring. We suggest higher rates than normal of N this year unless 

 the trees were excessively vigorous in 1978 or were heavily pruned 

 this past winter. 



Potassium (K) : K was low in many orchards and even deficient 

 in some in 1978, probably due to the demand for this element by 

 the large crop, or because the dry weather reduced its availability. 



The leaf scorch symptoms of K deficiency may be confused with 

 the leaf margin burn from calcium chloride sprays. However, unlike 

 leaf burn from calcium chloride sprays, the scorch of leaf margins 

 due to K deficiency progresses from the older leaves to the younger 

 leaves of current season shoots as the season advances. The scorch 

 may turn gray in color and leaf fall may occur late in the growing 

 season. 



The K requirements of apple trees with a large crop are high 

 because the fruit utilizes about 3 times as much K as N, Since 

 the quantity of K stored by the tree is extremely small, it seems 

 important to supply adequate K this spring on trees that had heavy 

 fruit set in 1978. 



The requirements of apple trees for K (expressed as K-,0) , based 

 on potential yields, are as follows: (a) less than 15 bu. 1.3 lbs,/ 

 tree; (b) 15 to 25 bu: 1,3 to 2,7 lbs, /tree; and (c) more than 

 25 bu: 2,7 to 4,3 lbs, /tree. It is necessary, however, to maintain 

 a balance among the essential nutrients for apple trees. For example, 

 excessive levels of K can reduce both leaf and fruit Ca, Therefore , 

 we strongly urge that you participate in our leaf analysis program to 

 more accurately determine the K needs of your apple trees . 



