170 Peach-Growing 



trouble is indirect and rests in the fact that the trees make 

 a more thrifty growth of leaves, hence the fruit is more 

 shaded than where these conditions do not obtain. By 

 properly thinning the tops, this difficulty should be readily 

 overcome. 



2. The varying effects of the mineral fertilizers, phos- 

 phoric acid and potash. 



3. The necessity of working out the fertilizer require- 

 ments in each individual orchard unless the different or- 

 chards in a community occupy sites the soils of which are 

 uniform and similar and have had essentially the same history 

 as to treatment, previous cropping, and the like. 



It should be observed that in some cases the continued 

 use of nitrogen has appeared to cause a reduction in the size 

 of the fruit. The decrease, however, has not been impor- 

 tant, since it did not impair the marketability of the fruit 

 appreciably, and the quantity produced was increased in 

 a marked degree. 



It has been suggested that the reduction in size of the 

 individual fruits as a result of the use of nitrogen is due to 

 action of the foliage, which is usually very abundant where 

 nitrogen is liberally applied, in withdrawing moisture 

 from the fruit, or at least in taking up moisture which would 

 otherwise go to the fruit. It is known that under some 

 conditions, moisture may be transferred from the fruit to 

 the leaves growing on the same branch. 



The reader having an orchard fertilizer problem in hand 

 who has reached this point now knows something of the 

 nature of his problem, but is perhaps no nearer its solution 

 than in the beginning. Only one course is open if the prob- 

 lem is to be solved in an economical and businesslike way. 

 The experiments conducted by the different stations have 



