Whiter Meeting. 305 



the sun, and at the same time the whitened twigs, assisted by the 

 bright mantle of snow on the ground, reflected or threw off the 

 maximum number of heat rays, thus keeping them quite cool, in 

 fact, one degree below the temperature of the air. These differ- 

 ences in temperature were noticeable only during times of sunlight. 

 It was interesting to note that when the blackened twig had be- 

 come quite warm that, if suddenly shaded, as by a passing cloud, 

 it would lose all of its heat that it had secured by reason of its 

 color in five minutes, and that seven minutes would be required 

 for it to warm up again after the shade was removed. 



In the case of natural colored twigs, since the colors are not 

 so pronounced as pure white and pure black, the differences in tem- 

 perature, of course, are at no time so great as under the artificial 

 conditions above mentioned, but they are great enough to cause, 

 perhaps, one-third of the difference in temperature of the case of 

 the extreme^ between the whitewashed and blackened twigs. It 

 is believed that great fluctuations in temperature within short per- 

 iods of time may have a very important bearing upon the killing 

 of fruit buds, especially in late winter. Indeed, it was found that 

 by spraying the trees with whitewash the blooming period in 

 spring could actually be held back for from three to five days. This 

 fact is not so important in itself as the probability is that there 

 are many times in late winter when, if the twigs become warmed 

 up and are thereby caused to make a very slight growth, they are 

 certain to be killed by subsequent low temperature. It is a well- 

 known fact that perfect fruit buds may safely withstand from ten 

 to twenty degrees below zero, but that, if slight growth has taken 

 place, they may be killed by a few degrees below freezing. Thus 

 it is seen that there may be many times, during bright, sunny 

 days in January and February, when a slight protection in the way 

 of shading or covering with some white material to reflect the 

 heat might prevent premature growth and the fruit buds thereby 

 be saved. 



Concerning the effects of pruning on the hardiness of peach 

 buds, W. H. Chandler, Assistant Horticulturist to the Missouri Ex- 

 periment Station, has carried on numerous experiments for the 

 past few years. He cites the fact that it is now known that winter 

 injury is due to the extraction of water from the cells. Cells which 

 do not lose their moisture easily and, therefore, are able to with- 

 stand drying conditions, are less injured in winter. This is why 

 the cells in young and succulent parts are usually most easily 

 killed — that is, they lose their moisture more readily and are not 



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