TWENTY-SIXTH SESSION. 
45 
While these facts have been established by the vegetable physiologist, the 
horticulturist seems not to have given the matter very much direct attention 
in studying the management of cultivated plants. During the past few years 
the writer has conducted some experiments at the Missouri State University, 
which indicate that their color bears a very important relation to the winter 
killing of peach buds, and to possible methods of its prevention. 
It is a well known fact that while flow^er buds of the peach are sometimes 
able to endure a temperature of 20 degrees or more below zero, without 
injury, they are at other times killed even at temperatures much higher than 
this, and have been known to be destroyed at temperatures above zero. Dur- 
ing the past winter flower buds of the peach were killed in some orchards in 
Missouri during December, when the mercury registered 12 degrees below 
zero. On the other hand, some peach trees in the same state endured a tem- 
perature of 26 degrees below* zero, during February, without injury to their 
buds, and they are now carrying a good crop of fruit. 
Observations during the past four or five winters convince me that the 
condition of the buds has much to do with their ability to safely endure cold. 
Perfect maturity of the buds in autumn seems to favor their safe wintering; 
while imperfect maturity of the tissues, from lack of moisture, or on the 
other hand, from excessive and prolonged growth during a warm, moist 
autumn, seems to oppose their endurance of severe cold. If peach trees pre- 
maturely approach a dormant condition during a dry time in late summer, 
and are subsequently stimulated into autumn growth by warm rains, as is 
sometimes indicated by the blossoming of the trees in autumn, the remaining 
buds are usually very liable to injury In winter. 
Again, peach buds often grow perceptibly during mild weather in winter. 
We are in the habit of thinking of peach buds as being dormant during win- 
ter. As a matter of fact in this climate, they grow perceptibly during the 
winter months. The most frequent cause of winter killing in this section is 
severe freezing of the buds after they have been rendered liable to injury 
by making too much growth on warm winter days. 
The swelling or growth of peach buds in winter is due to the heat they 
receive, is independent of root action and may take place when the roots are 
frozen. Considering the fact that the purple coloring matter of plants is 
admirably adapted to absorbing heat, the idea suggested itself that if the 
twigs were whitened to reflect rather than absorb the heat, during brighf 
sunlight, there would be less danger of swelling of the buds on warm winter 
days, and consequently less danger of subsequent winter killing. 
During the winter of 1895-6 peach trees of several varieties were whitened 
by spraying with lime whitewash. In order to thoroughly encrust the twigs 
with lime, two sprayings were necessary, just as two coats of paint are nec- 
essary to cover wood. Whenever this was washed off to any extent another 
coat was applied. 
The winter was marked by changeable temperatures. During February 
whitened and unwhitened buds were examined weekly under the microscope. 
Sections of whitened buds revealed the fact that they were not growing per- 
ceptibly, while sections of unwhitened buds showed that they were swelling 
more or less every week. At the time of blossoming it was found that the 
pistils had been killed in 80 per cent of the unwhitened buds while only 20 
per cent of the whitened buds had been destroyed. Warm weather came on 
very suddenly and most fruit trees blossomed at about the same time. There 
was a difference of about one day in the time of blossoming of whitened and 
