Fertilizing the Commercial Apple Orchard 193 



or intercrops, and possibly as an accompaniment of fertil- 

 izer applications. In the latter relation its chief effect 

 has been on growth. Phosphorus is also generally valu- 

 able in connection with leguminous covers." 



6. Potash, when applied alone, gave an increased yield 

 in some experiments, a material increase in a few, but in 

 some instances had an injurious effect. On account of the 

 impossibility of denning just what the soil needs without 

 experimentation, it is better to defer general use of potash 

 until definite evidence of its value is secured. This can 

 be done through a home experiment as outlined later in 

 this chapter. 



7. " The red color in apples can not be increased mate- 

 rially by any kind of fertilization, although potash and 

 possibly phosphorus may sometimes assist very slightly. 

 These colors are directly dependent on sunlight and matur- 

 ity, with the latter occurring preferably on the tree. 

 Hence such influences as normal development, late picking, 

 light soils, open pruning, and mildly injurious or defoliat- 

 ing sprays are the chief practical means of increasing the 

 reds in fruits, while opposite conditions tend to decrease 

 hum." 



\j 8. " The distinctly retarding influence of nitrogenous 

 fertilizers and manure on color is simply due to delayed 

 maturity, and is often an advantage in the case of the more 

 northern varieties, such as Baldwin, Hubbardston and 

 Mcintosh, when grown in Pennsylvania. In such varie- 

 ties, the color reduction is readily overcome by deferring 

 the picking. With the York Imperial and similar, long- 

 seasoned varieties, however, it may also be necessary to use 

 nitrogen more sparingly and to utilize the other direct 

 aids to color as much as possible." 



