Character of Winter-Killing 303 



be particularly essential following an unusually dry sum- 

 mer. (4) That low, wet places be tile-drained, and air- 

 drained if such a thing is possible." 



It should be added that the trees are less liable to 

 injury if they go into the winter strong and undepleted. 

 Plants weakened by drought, lack of tillage, over-bearing, 

 borers, San Jose scale and diseases, are specially liable to 

 winter-injury. 



The recent careful studies of Chandler, "The Killing of 

 Plant Tissues by Low Temperature" (Mo. Research Bull. 

 No. 8), have thrown much light on winter-killing. "There 

 are several forms of injury from cold," he states, "some of 

 them purely mechanical, such as tearing of tissue due to 

 tension developed at low temperature, or evaporation 

 from the surface when the conducting tissue is frozen so 

 as to prevent the movement of water to that tissue, and 

 killing as a result of long -continued exposiu-e to low 

 temperatmre. 



"With all plant-tissues, when a certain temperature is 

 reached very shortly after thawing, it will be found that 

 the tissue has taken on a brown, water-soaked appearance, 

 and evaporation from that tissue is much more rapid than 

 from living tissue. These are characteristics of plant- 

 tissue frozen to death. 



"Results of many investigations have shown that 

 dming freezing (which may or may not result in freezing 

 to death), ice forms in the tissue, generally not in the 

 cells but in the intercellular spaces, the water moving out 

 of the cells to form crystals in these spaces. The most 

 commonly accepted theory is that killing from cold results 

 from the withdrawal of water from the protoplasm. The 

 amount of water-loss necessary to result in death va.ries 

 with the different plants and different tissues." 



