-23- 



Magnesi um : There is little evidence that either too little 

 or too much Mg directly affects fruit quality. However, excess 

 Mg interferes with Ca just as does excess K, so excessive amounts 

 of Mg will produce Ca deficiency effects in fruit. 



Phosphorus : P deficiency can reduce tree growth and yield, and 

 in several parts of the world it has also been shown to cause 

 increased amounts of breakdown of apples during storage. How- 

 ever, in North America there has been very little evidence f6r 

 P deficiency in fruit. We have recently found that high levels 

 of P in apples, especially in combination with low levels of 

 Ca, greatly increased breakdown of apples during storage. 



Boron : B deficiency has occurred over much of North America, 

 causing both internal and external cork development in fruit. 

 Excessive levels of B in fruit can cause earlier maturation and 

 increased amounts of water core at harvest, and increased amounts 

 of breakdown after storage. Thus, a moderate level of B is 

 important for good fruit quality. 



B also influences Ca movement in the tree. If it is deficient, 

 less Ca is moved to the fruit and Ca deficiency can result. It 

 is therefore important to maintain adequate B levels as a part of 

 a program to avoid Ca deficiency. 



POMOLOGICAL NOTES 



For Those Who Care To Know . The first mimeographed copies of 

 FRUIT NOTES was issued in March, 1936 with Bill Thies, Editor, at 

 about the time of the spring flood. (The spring flood of 1936 is 

 well remembered by some of us older folks.) With an exception 

 of a few months when no issue was prepared, it has appeared at 

 regular intervals from 1936 to the present time. William Lord be- 

 came Editor in 1955 and William Bramlage, Co-editor, in 1966. We 

 have a mailing list of approximately 1600 and it is mailed to 

 19 foreign countries. 



