Native Vegetation 
i9 
tice that stimulates the production of tender shoots and a cultural 
method that favors the development of succulent tissue may result 
in more or less freezing. Temperature conditions preceding and 
leading up to a freeze are important in influencing the resisting 
power of a plant. A series of warm days preceding a freeze, which 
permits the formation of many new plant cells, with their thin 
walls and an abundance of water, is especially injurious. Such 
warm days are prevalent in Colorado, coming even weeks ahead 
of the last frost. During a favorable spring, the minimum and 
maximum temperatures, as well as the mean, for the 24 hours of 
the day, should become gradually greater. Under such circum¬ 
stances, even though the warm days induce the swelling of buds, 
they are better able to undergo the low temperatures of the nights. 
An unfavorable spring is one whose maximum, minimum and 
mean daily temperatures fluctuate greatly. Many mountain valleys 
are so shaded during a portion of the day that fruit buds are de¬ 
layed in opening. A shaded mountain slope is quite likely to have 
daily extremes of temperature that are much less than those of a 
sunny slope. The latter warms up rapidly and to a high point in 
the day time, and at night cools as rapidly, and reaches as low a 
temperature as its neighboring shaded slope. Furthermore, if 
there be any efficacy in the gradual thawing of frosted plant tis¬ 
sues, mountain shadows will be of value in retarding the rate of 
this process. 
In the Monthly Weather Review for March, 1912, are pub¬ 
lished data showing temperatures injurious to peaches, apples and 
pears in various stages of development. The data were compiled 
by a committee appointed by the Fruit Growers’ Association of the 
Grand Valley, Colorado. The tables (VII and VIII) are taken 
verbatim from the Monthly Weather Review. 
TABLE VII.—SHOWING AT WHAT TEMPERATURES SMUDGING IS NECESSARY 
IN THE VARIOUS STAGES OF DEVELOPMENT OF PEACH BUDS. 
Degrees 
Peaches % inch in diameter 
Dropping the shuck. 
Setting. 
Full bloom. 
Buds in pink . 
Buds swelling. 
Buds dormant . 
30 
31 
31 
29 to 30 
22 
15 
15 
