284 The Principles of Fruit -growing. 



Hansen* writes as follows upon this subject for 

 Dakota conditions: "Sun -scald causes great loss in 

 northwest prairie orchards. By sun -scald is meant 

 the alternate thawing and freezing of the stem on 

 the southwest side in late winter, causing the bark 

 to die and decay. Oftentimes the dead, blackened 

 bark separates entirely from the stem. Orchardists 

 now generally recognize the cause of the trouble, and 

 prevent it by shading the stem in some way. Trees 

 planted and kept with stem leaning toward the 

 southwest until the branches shade the trunk, are 

 free from it. Some fruit-growers set a board, or 

 two boards nailed together trough -fashion, on the 

 southwest side ; others use corn stalks, wire netting, 

 or lath. Low -headed trees are best for severe lo- 

 cations ; in more favorable sections trees may be 

 headed two -and- a- half to three feet high. Tall 

 trunks suffer more from sun -scald and severe 

 winds." 



Trees are apt to suffer with 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 limbs to the intense heat of the 

 sun, and the bark is likely to blister and be killed, 

 after which borers are very apt to finish the work 

 of destruction. In all interior hot regions, there- 

 fore, it is well to exercise caution in the pruning 

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



*N. E. Hansen, "Fruit Culture," Bull. 50, S. Dak. Exp. Sta., 1897. 



