130 
WISCONSIN HORTICULTURE 
May, 1918 
Winter Injury to Cherry Blossom 
Buds. 
Prof. R. H. Roberts 
College of Agriculture 
In general the troubles which af- 
fect a fruit tree are of interest to 
the grower only when they reduce 
the crop below a reasonable yield. 
As a result it is only every few 
years that more than passing inter- 
est is shown in the matter of win- 
ter injury to cherry blossom buds. 
While this trouble 'is common in, 
Wisconsin it is seldom that the in- 
jury is sufficiently severe to causej 
a crop failure, as was the case in 
the winter of 1915. 
When no injury occurs there is 
a normal thinning of the fruit af- 
ter the blossom season to such an 
extent that only a relatively small 
portion of the total number of blos- 
soms will produce fruit. It is not 
unusual, as in the past summer, 
that trees which had as many as 
half of their blossom buds killed 
during the previous winter will 
produce nearly a full crop of 
fruit. It is desirable that this in-! 
jury should be prevented as the 
weather is not always finely 
enough adjusted to do just the 
proper amount of thinning of the 
fruit buds. 
In order to get a better under- 
standing of the nature and occur- 
rence of this trouble, detailed stud- 
ies of this problem were undertak- 
en by the Department of Horti- 
culture of the University. 
A limited survey of the condi- 
tions existing in the Sturgeon; 
Bay district this last spring 
revealed several points of in- 
terest in connection with the 
prevalence of the injury. While 
these are a matter of common 
knowledge to the growers they will 
be stated again in order to get the 
conditions clearly in mind: 
1. Montmorency trees and 
young Richmond trees were very 
free from injury. 
2. The vigor of the trees, as 
measured by the amount of growth, 
seemed to be the factor determin- 
ing the Occurrence of the injury. 
3. There was less injury in the 
tops of the trees than in the low-, 
er parts. 
4. Trees slightly defoliated 
with shot-hole showed less injury 
than trees with normal foliage. 
5. Tlie young trees and shot- 
hole trees were later in blossom- 
ing than the older trees. 
6. Where injury is common, 
the shortest and longest spurs had 
less injury than spurs of average 
length. 
7. The larger buds were most 
injured. 
After a consideration of these 
facts it is apparent that immatur- 
ity of the trees is not associated 
with the occurrence of winter kill- 
ing. In fact, the more vigorous, 
later growing trees were much less 
subject to injury. 
Following a detailed study of 
the blossom buds a condition was 
found which was directly associat- 
ed with the appearance of the 
trouble. This condition was the 
amount or degree of development 
which the buds have reached when 
the winter season begins. We may 
say, then, that the more developed 
the buds are, the more susceptible 
they are to injury. 
From a study of the wood 
growth and fruiting habit of the 
trees we find that the relative de- 
velopment of the buds is in propor- 
tion to the amount of growth 
which the tree makes. As the 
amount of growth increased less 
bud development was found. 
The trees which make an average 
terminal growth of about ten 
inches are very largely free from 
injury. This might be suggested 
as an arbitrary ideal to aim at in 
regulating the vigor of the tree 
with the object of decreasing the 
winter injury of the blossom buds. 
At least we are able to modify the 
relative development of the buds, 
and their consequent susceptibility 
to injury, by maintaining a vigor- 
ous growth of the trees. This 
vigor depends of course upon the 
cultivation, the soil fertility and 
the pruning. 
Naturally we can expect the 
weather conditions of some sea- 
sons to be such that no in- 
jury will occur, or in oth- 
er seasons that the injury will be 
severe regardless of the conditions 
of the buds in early winter. On 
the other hand, the present obser- 
vations would indicate that much 
of the injury especially common to 
the older, weaker growing trees 
could be prevented by maintaining 
a more vigorous tree and thus pre- 
vent the extreme development of 
the blossom buds to the stage at 
which they are found to be very 
subject to winter killing. 
It doesn’t matter who started 
this war, Uncle Sam will finish it. 
Conservation, concentration, and 
consecration — for the sake of those 
at the front. 
Only a slacker could stand idly 
on the sidewalk and criticize as the 
army of workers marches by. 
