1008 
ing power of the same varieties of fruit 
during different degrees of development. 
The United States Department of Agri- 
culture makes the statement that the 
danger point for apples when they are 
showing pink is 20 degrees above zero; 
in full bloom, 26 degrees above zero. 
Pears showing pink are in danger at 20 
degrees above zero, in full bloom 27 de- 
grees above; peaches showing pink, 23 de- 
grees above and in full bloom, 28 degrees 
above. It will thus be observed that 
there is substantial agreement between 
the conclusions reached by the Missouri 
Agricultural Experiment Station and 
those of the United States Department 
of Agriculture, although these conclusions 
are differently expressed. 
Mr. P. J. O’Gara states that in Southern 
Oregon the temperature at which the apri- 
cot is injured when in the bud is 28 de- 
grees above zero, and 30 degrees when in 
blossom. Cherries are injured at 29 de- 
grees, just before the blossoms open, and 
plums are injured at 30 degrees above 
zero when the flowers begin to show 
white. 
It should be observed further that the 
latitude to which a tree is acclimated has 
much to do in determining the degree of 
cold it will stand without injury. Trees 
of the same varieties brought from Flor- 
ida will not stand the cold of the North- 
ern climate as well as those grown in the 
North, which have for several years, per- 
haps for generations, been used to the 
colder atmosphere. Furthermore, it 
makes a difference whether the cold comes 
suddenly or gradually. It is with plant 
life as with animal life, that the tendency 
of nature is to provide against injuries 
caused by sudden changes. Animals suf- 
fer more from cold if the change is sud- 
den than if itis gradual. In the gradual 
changes there is a closing of the pores of 
the skin, a shrinking of the muscles and 
drawing upon the food substances for the 
manufacture of heat, a lighting of the 
fires of the system that protects in a de- 
gree not possible where the change is sud- 
‘den. The same law prevails among 
plants, but not in the same degree. How- 
ever, it is observable that following a 
very warm day, if it should turn suddenly 
ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 
cold, the fruit buds are much more sub- 
ject to injury than if the same degree of 
temperature followed a cool day. In the 
winter of 1908 and 1909 in the Nortbh- 
western part of the United States, the tem- 
perature was lower during the months of 
January and February than for eighteen 
years before, and more damage was done 
to the tender varieties of fruit during 
that winter than had ever been known in 
the history of fruit growing in that re- 
gion. We made in our own orchard and 
in the orchards of our neighbors the fol- 
lowing observations: 
First’ Peach trees and the _ trees 
that belong to the prunus family, such 
as almonds and apricots, are among the 
tenderest trees and have less power to 
resist cold than apples, pears and other 
varieties. The almond will stand about 
14 degrees below zero without killing; 
the peach will stand about 18 degrees. 
Among the varieties of peaches on our 
place the Harly Crawfords were the ten- 
derest, while the Elbertas, Carmens and 
Salways were comparatively hardy. <A 
few feet of altitude when the mercury 
is down to the danger point may deter- 
mine whether an orchard will be killed or 
not. For instance, in one orchard the 
trees were killed in a little depression 
or draw that ran through the place, but 
at a point twenty feet higher they were 
not killed. It was argued by some of the 
neighbors that this was due, in part, to 
the fact that this low portion of land was 
irrigated more and did not mature the 
wood as well, or that the wood was too 
sappy, and therefore more easily frozen. 
In making other observations I have con- 
cluded that there may be some force in 
this, and that if an orchard has been 
properly irrigated so that it has matured 
its wood normally, it is in better condi- 
tion to stand the cold than where it is 
overirrigated, and therefore the wood 
sappy; or where it has lacked irrigation, 
and therefore the tree not sufficiently vi- 
talized. Among the apples the cheaper va- 
rieties generally stood the freeze better 
than the higher grades. The exception 
to this rule was in the case of the Ben 
Davis, on which there was very little 
fruit the following year. It was shown 
