148 



FUNDAMENTALS OF FRUIT PRODUCTION 



Table 36. — The Potash Content of a 7-year Old Apple Tree 

 (Expressed in percentages of dry weight") 



while the phosphorus content was not materially greater than in trees bearing 

 few seeds. Warren^^'' found that in peach, apple, plum and pear trees the ash of 

 the leaves contained less potash in years when the crop was large (see Table 37). 



Table 37. — The Potash Content op Peach Leaves in Bearing and Non-bearing 



Years'" 



This suggests that fruit trees usually take up more potassium from the soil than 

 is actually required, when they are not bearing fruit. 



2: 5: 



Fig. 16. — Potassium content of apple spurs in percentages of dry weight; bearing 

 spurs represented by continuous lines, non-bearing spurs by broken lines and barren spurs 

 by dot-dash lines. (After Hooker.'^°°) 



hi Spurs.— Figure 16 shows that the potassium content of bearing spurs rises 

 to a very high maximum in May. This increment passes into the fruit and the 



