PRUNING PRINCIPLES 85 



to be found in the state of Washington,* where the Cascade 

 mountains divide the state into two climates, a cloudy humid 

 area to the west and a clear dry one to the east. In the 

 humid area the abundance of moisture in air and soil, and 

 the mild climate favor excessive wood development, often 

 an annual growth of 6 to 10 feet of cherry and prune 

 branches. The trees continue to grow late in the autumn and 

 fully ripened wood is often difficult to secure. Severe winter 

 pruning aggravates the evil of this excessive wood growth 

 by making more and longer wood growths. To check 

 growth, therefore, growers resort to summer pruning, shoot- 

 pinching and even root pruning. The eastern or dry area 

 is characterized by "a long, dry summer with a -fierce, 

 scorching sun and strong, drying winds . . . followed by 

 a severe winter with fluctuating temperature and sudden 

 changes. In portions of the fruit belt there is barely enough 

 moisture in the ground to sustain a tree." Under these con- 

 ditions trees "come to maturity at an early age, and produce 

 fruit at a time in their lives when they ought to be making 

 wood growth and establishing a strong, healthy frame for 

 future usefulness." In this region severe pruning is done 

 in winter so as to overcome the tendency for the trees to 

 bear too young. Cherries fruit at two years; pears an 1 

 apples bear full crops at five or six. The winter pruning 

 is done to increase wood and leaf growth. Summer prun- 

 ing and shoot-pinching are avoided in the dry area. In the 

 dry plains region, the tops of trees must be kept more dense 

 than in moister regions. 



The fruit in these dry areas is less likely to suffer from 

 shade than from exposure to sun and wind. In the east 

 most orchardists keep the lower limbs up from the ground, 

 to improve the flavor and the color of the fruit; in the 

 central west this precaution is needless ; therefore, very low- 

 headed trees are more popular than in the east, because the 

 trunks and. branches are believed thus to be better protected 

 from sun scald. 



* Bulletin 25, Washington Experiment Station. 



