CLIMATOLOGY 23 



Dr. J. C. Whitten, of the University of Missouri. 

 At any rate Dr. Whitten has been the chief exponent 

 of this method and has made the most extensive ex- 

 periments with it. It consists in spraying the bear- 

 ing parts of the peach tree with whitewash during 

 winter and spring on the theory that the white stems 

 reflect instead of absorb the heat from the sun's rays. 

 It has been shown by Dr. Whitten and other experi- 

 menters that the blooming of peach trees and other 

 fruits is dependent upon the local absorption of heat 

 and is almost absolutely independent of root ac- 

 tion. For instance, the branch of a fruit tree brought 

 into a greenhouse will blossom even while the por- 

 tion of the tree outside the greenhouse is exposed to 

 zero temperatures and while the roots still stand in 

 frozen soil. 



The experiments have shown further that peach 

 twigs which have been whitened will actually main- 

 tain a temperature several degrees lower than twigs 

 covered with black or left in their natural color. 

 Furthermore and this is by far the most important 

 practical test the blossoming of peach trees is ac- 

 tually retarded by this method by a period of from 

 2 to 10 days. Dr. Whitten has recently stated that 

 in the orchard of the Missouri Experiment Station 

 peach trees have been treated by the whitewashing 

 method for 10 successive years. This treatment has 

 been given to alternate rows, adjoining rows of trees 

 being left always without treatment. During this 

 lo-year period there have been four good peach 

 crops and five failures on the non-treated orchard 

 and one partial crop. The whitewashed rows have 

 failed but twice during the same time. In other 

 words, the treated trees have yielded three crops 

 more in 10 years than the untreated trees. In this 

 connection one should not overlook the fact that a 



