294 



The Principles of Fruit-growing 



headed trees are best for severe locations; in more favor- 

 able sections trees may be headed 23^ to 3 feet high. Tall 

 trunks suffer more from sun-scald and severe winds." 



Trees are liable to injury from sun-scald after a heavy 

 pruning, especially if they have been allowed to grow too 



thick in the first place. 

 Cutting out heavily 

 from the center of the 

 tree exposes the oblique 

 and horizontal hmbs to 

 the intense heat of the 

 sun, and the bark is 

 Hable to blister and be 

 killed, after which borers 

 are very likely to finish 

 the work of destruction. 

 In all interior hot re- 

 gions, therefore, it is 

 well to exercise caution 



Fig. 107. Aborted apple tree. j^^ ^j^g pruning of the 



tops of trees. It is better to keep the top somewhat thin 

 and open from the start, rather than to allow it to 

 become overgrown and then to make a sudden correction. 

 Perhaps sun-scald is a form of winter injury due to the 

 rapid fall of temperature when the sun leaves the south- 

 western side of the tree; but the above treatment appHes 

 in any case. 



Borers, 



The best treatment for borers and similar insect 

 pests is to watch the plants carefully, and to dig the 

 insects out at least twice every year. In grounds kept in 

 clean tillage, such insects are rarely so troublesome as 



