New York Agricultural Experiment Station. 303 



to sway) to an air current of 22.3 miles per hour (10 m. per second), 

 and after 3 to 6 days all of the loose twigs had died back more or less 

 while the fixed ones remained apparently normal to the end of the 

 experiment. That is, perfect rigidity seems to afford total immmiity 

 from wind injuries, while swajdng or bending result in injury. 



In order to distinguish between the swaying and drying effects of 

 strong winds the experiments were repeated, the plants being kept 

 wet by means of a spray of water. Similar results were obtained, 

 and it was fomid that the bending of plant structures has a marked 

 influence on the transpiration rate of both leaves and twigs even when 

 the surrounding air is saturated with moisture. 



When the wind rates used in these experiments are compared to 

 those frequently occurring during the dormant period of fruit trees 

 they are not very high, and their pressure is therefore also lower than 

 that to which our trees are often subjected. The following table 

 taken from an article by Keller^ shows the pressure resulting from 

 different -^dnd rates. 



Table IV. — The Rate and Resulting Pressure of the Wind. 



A wind blowing at the rate of 25 to 40 miles per hour is not at all 

 uncommon in most regions of the United States and frequently a rate 

 of 50 to 60 miles is maintained for some time. 



Bernbeck's results are especially interesting when compared with 

 the above field observations of 1911. Most of the injuries occurring 

 during the winter of 1910-11 were accompanied by radial clefts in 



1 E. Keller. The hygiene of the small chemical laboratory. 

 J OUT. Ind. Eng. Chem. 2:246-51. 1910, 



