260 



PRINCIPLES AND PRACTICE OF PRUNING 



be taken to cut back with comparative severity. Only 

 in extraordinary cases, however, should the cutting ex- 

 tend back to two or three-year-old branches. 



In treating winter-injured peach trees, Waugh left one block 

 unpruned, another pruned in midsummer, a third cut back one-third 

 to three-fourths of the previous year's growth, and a fourth headed 

 back near the trunk so only the stubs of main branches were left. 

 While a large number (93 per cent) of the unpruned trees lived, 

 the growth made by the headed-in trees was much better. Ninety 

 per cent lived. The experiment also seems to indicate that trees 

 seriously injured by freezing should not be cut back close to the 

 main trunks. Only 52 per cent of the trees so treated lived after 



FIG. 222— PEACH IN FOREGROUND SHOWS GOOD GROWTH 



This picture taken in June sliows how trees differ. The tree at the left is slow 



starting into growth. Both trees were cut back severely after winter Injury. 



treatment. (Compare statements with those of Chandler 202 and 

 Whitten 203.) 



Experiments conducted at the Michigan sub-station indicate that 

 pruning (hcadirg-in) of peach trees late in the fall and in early 

 winter if continued may result in serious injury. 



Ex[)eriments conducted* for years to determine the best seasons 



* Hawaii station Report, 1913, Pages 22-26. 



