RESULTS OF MEASUREMENTS. 69 



trees which in some cases served as a partial protection to the orchards. 

 This storm was followed on the night of April 29 by a brisk north- 

 west wind and a temperature of 31 degrees, but no precipitation. 

 On May 2 a killing frost again occurred with wind from the south- 

 east and a temperature of 26 degrees. On May 6 and 7 there were 

 "clear frosts," with wind in the northeast. The character of these 

 several nights is of special interest in showing that only the storm from 

 the northwest, which was accom/panied by precipitation, had any marked 

 effect upon the orchard trees. 



Throughout Nebraska it was noted during the summer that orchards 

 protected by windbreaks were .bearing more heavily than unpro- 

 tected ones, in many of which there was, in fact, no crop at all. 

 Before the later apple harvest a careful study was made of the orchards 

 in the vicinity of David City, where there are both protected and un- 

 protected orchards growing under otherwise very similar conditions 

 and offering excellent opportunities for comparison. 



In wholly unprotected orchards it was found that the trees were 

 bearing little or nothing on the northwest branches and in the exposed 

 tops, though the south and east branches of the same trees were 

 bearing moderately. This indicated that most damage had been 

 done by the storm from the northwest, and that the trees were, 

 in a measure, a shelter for themselves in this storm. Similarly the 

 trees on the exposed north and west sides of the orchard, as a whole, 

 frequently bore less heavily than the parts of the orchard which 

 had had the protection of these trees. Some wholly unprotected 

 orchards, that is, orchards without the protection of taller forest 

 trees, were almost entirely devoid of fruit. Most important of 

 all, none of the trees in orchards well protected by a belt of forest 

 trees showed marked declines from a normal crop. Twenty-eight 

 out of thirty unprotected orchards gave a yield ranging from less 

 than 1 to 3 pecks of apples per tree, though one orchard of this class 

 yielded from 2 to 3 bushels per tree. Partially protected orchards 

 gave an average yield per tree of from one-half bushel to 3 bushels. 

 Five well-protected orchards gave an average yield per tree of 4.9 

 bushels. Of the latter, one yielded 5.4 bushels per tree and another 

 one 10.9 bushels. 



The benefit of a windbreak is here conclusively shown, and there 

 is little need to figure it out in dollars and cents. If the orchard 

 is worth $100 per acre per year, it could easily be shown that the 

 value of a windbreak in such a year as 1908 is at least $80 per acre 

 over a belt ten times as wide as the height of the windbreak. 



Storms of the kind described above, are not at all unusual in the 

 northern fruit belt; in the Middle West they have occurred several 

 times during the past 10 years at the critical period in the blooming 

 of orchard trees. In fact, any lowering of the temperature at this 



