MANAGEMENT 



43 



for work under the trees. An adjustment which is 

 often applied to disk harrows, spring-tooth harrows 

 and smoothing harrows is a rigid middle section 

 inserted so as to extend the two halves of the orig- 

 inal implement out under the trees while allowing 

 the horses to walk in the middle of the tree space. 

 This is illustrated for the disk harrow in Figure 20. 

 With such modern conveniences as these, it is possi- 



FIG. 19 THE HORSE HOE FOR CLOSE CULTIVATION 



ble t<5 give thorough cultivation at low cost and at 

 the same time to work closely under the branches 

 of low-headed fruit trees. 



THE COVER CROP 



The term cover crop is applied to any annual crop 

 sown between the trees and for their special benefit. 

 It is usually sown after the regular period of cultiva- 

 tion, that is, between July 15 and August i, though 



