NOTES ON THE VARIOUS SPECIES 249 



pieces in summer storms after it has attained fair 

 size. It is certain to lose large limbs by the time 

 it attains a spread of twelve or fourteen feet. 

 Preferably, it should be pruned annually and re- 

 strained from getting so large. Broken tops can 

 often be propped up to last out the season. No 

 effort should usually be made to remedy the trou- 

 ble permanently. Cut off all the split limbs and 

 prune the others back severely. In a few years 

 the top will regain size and symmetry. 



CHERRY 



The black-knot which infests cherry trees and 

 other stone fruits so widely can be cured only by 

 complete excision or by the removal of the limb 

 on which it occurs. The parts removed must be 

 burned. It has not yet been found possible to kill 

 the causal fungus by means of any kind of appli- 

 cation. 



In making incisions in the cherry difficulty some- 

 times arises from the fact that the bark rolls 

 back from the cut edge, detaching itself from the 

 wood and drying out. The same phenomenon 

 accompanies frost cracks and greatly increases 

 their seriousness in the cherry. The explanation 

 of course is that the outer bark of the tree is 

 under tension, and when the opportunity occurs 

 for it to contract it does so and tears the soft inner 

 cortex from the wood. A few nails half an inch 



