STATE POMOLOGICAL SOCIETY. 63 



Phosphoric acid does not appear to quickly become a limiting 

 factor in fruit production. As a usual thing most soils, except 

 those of the Atlantic Coastal Plains and some alluvial soils of 

 the central states, are fairly well supplied with phosphorus. 

 Phosphorus is a necessary factor in cell division and without 

 phosphorus no growth can take place. In peaches we find that 

 phosphorus tends to slightly delay maturity. This is directly 

 opposite to its effect upon most plants. In most cases the ripen- 

 ing process is forwarded by the use of phosphoric acid. 



What the behavior of phosphorus, in this respect, is with 

 apples, I cannot say. We have some evidence that, in peaches 

 at least, too much phosphoric acid may seriously interfere with 

 proper pollination of the blossoms and thus lessen the set of 

 fruit. 



Lime may be a limiting factor in apple growing, but it is my 

 opinion that such cases are rare. 



Stewart found in Pennsylvania that potash in combination 

 with other fertilizers increased the size of fruit to some degree. 

 His results coincide with our own experience in fertilizing 

 peaches. 



There are other elements of plant food that may be limitless 

 in certain isolated cases. Of these, magnesia and sulphur are 

 the most likely to be so, although recent work with vegetables 

 and grains would indicate that some soils are deficient in sul- 

 phur. Iron is necessary to all plant growth, but practically all 

 orchard soils are sufficiently supplied with this element. Silica, 

 sodium and aluminum are probably present in great quantities 

 in all soils and we need pay no attention to them. 



No general fertilizer treatment can be recommended for the 

 apple crop. The orchard in question may need it or it may not. 

 Oftentimes it is advisable to apply readily available plant food 

 to young trees, although the soil may be plentifully supplied. 

 Such treatment will enable the young tree to quickly establish 

 itself. After being once established and given an impetus for 

 growth, it may not be necessary to add any more fertilizers. 



The wise thing to do before resorting to the use of fertilizers, 

 either commercial or barnyard manure, is to be sure that all lim- 

 iting factors other than potash, phosphoric acid or nitrogen, are 

 under control. This would mean that the moisture supply 

 should be properly regulated either through drainage, irrigation 

 or maintaining the humus content of the soil. I believe that 



