FERTILIZING THE TREES 



431 



cover crops. When proper pruning, thinning of the fruit (with 

 the exception of the cherry) , and fertilization, especially with 

 nitrogen fertilizers, are practiced, in addition to thorough cul- 

 tivation and the turning under of heavy cover crops, little is 

 left to be desired. 



Peaches and apricots are very shallow-rooted under most 

 soil conditions, and as a result would probably suffer from 

 lack of moisture when in competition with grass much more 

 than apples would. Although plums and cherries might thrive 

 better than peaches and apricots under a system of sod mulch, 

 still it is very questionable whether results equal to those se- 

 cured under tillage would ever be obtained. 



Like all other fruits, the Tpear thrives well under a system 

 of clean cultivation and cover crops. Because of the fact that 

 growth may be vigorous and succulent under cultivated con- 

 ditions, thus resulting in more injury from fire blight, pear 

 orchards are often left in sod in order to check such growth. 

 If proper and thorough methods of blight control are practiced, 

 however, it is questionable whether it will pay to check growth 

 too severely, decrease the bearing area, and reduce total yields 

 by keeping the orchards in sod. 'A system of sod and cultiva- 

 tion in alternate years may be desirable. Cease cultivation 

 earlier in the season than with the apple. 



The quince thrives best when the soil is cultivated, but 

 appears to do fairly well under sod mulch conditions also. In 

 some regions the quince is so susceptible to fire blight that it is 

 almost necessary to practice some system of sod culture in 

 order to check rapid growth and thus reduce fire-blight injury. 



Fertilizing the Trees 



The Apple 



It is practically impossible to consider orchard fertilization 

 without knowing the system of orchard soil management that 

 is being used and the kind of soil upon which the orchard is 



