12 The Colorado Experiment Station. 
2. The more evenly distributed the fruit on the tree the more 
uniform will be the size and color of the pack. 
3. That Winesaps respond to thinning by increased size and 
better color when thinned as late as July 20. 
4. The earlier that thinning can be done, the better will be the 
returns from the fruit sold and the greater will be the vitality of 
the tree. 
5. The best results are attained in thinning an old Winesap 
tree, by leaving the apples from 9 to 10 inches apart. 
6. That proper pruning, and keeping the trees a proper dis¬ 
tance from each other will facilitate thinning. 
7. That systematic, annual, uniform thinning done from the 
time the trees come into bearing, should have much to do in secur¬ 
ing an annual crop, thereby doing away with the so-called “off 
year” bearing of some of the apple varieties. 
WINTER AND FROST INJURIES OF FRUIT TREES 
The object of the following discussion is to define as nearly as 
possible the different effects of freezing temperatures upon fruit 
trees and also to show that these effects often cause the death of 
fruit trees in Colorado. The subject divides itself into the follow¬ 
ing heads, namely: winter injury of young trees; winter injury of 
old trees; and spring frost injuries. In this bulletin, injury to peach 
and apple trees only will be discussed. 
WINTER INJURY OE YOUNG TREES. 
This divides itself into two heads, injury done to young apple 
trees, and that done to young peach trees. Young apple trees are 
injured for the most part, by freezing at the ground line, and by 
sun scalding on the trunks. Injury to young apple trees at the 
ground line is often caused by very low temperatures, resulting in 
perpendicular cracks which extend on the trunk from the ground 
line, or just below, upwards to a distance of an inch, or sometimes 
more. There may be from one to five cracks depending upon the 
severity of the freeze. In some varieties, such as the Rome Beauty 
for instance, it is often found that the bark bridges up between these 
cracks, causing a complete girdling of the trees, which often kills 
the tree. In most varieties, such as Jonathan and Winesap, the tree 
generally has strength enough to heal these wounds over so that 
in a few years they are hardly noticeable. In those cases where 
there is danger of killing the tree, it would be a good thing to fill 
the cracks with wax, or it might be of value to heap damp earth 
around the base of such a tree. If very bad cracks (Fig. i) were 
found and taken in time, it might be possible to save the tree by 
bridge grafting. 
