284 The Principles of Fruit-growing. 
Hansen* writes as follows upon this subject for 
Dakota conditions: ‘“Sun-seald 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, 
