The Hood River glacier. (Hood River, Or.) 1889-1933, 1920-07-08
Summer Pruning
By Gordon G. Brown

There are few instances in which
the writer believes summer pruning of
young trees from two to five years of
age is advisable, but in most cases it
should be very light. As preface to
what may be said along this line it is
well to observe how the young tree
functions and responds to purning. AS
a general proposition it is now fully
demonstrated that pruning at any time,
whether winter or summer, is a neces-
sary evil which cannot be avoided for
obvious reasons. Data is now available
which shows clearly that pruning young
trees is devitalizing, both in growth
and bearing age. Without exception
results with apricot, cherry, peach,
! pear, plum and prune demonstrate this
truth. This is especially so with plums
and prunes. At the California expert
ment station the fruits enumerated
were classified into three groups, ac-
cording to the method by which pruned.
Group ! composed those severely thin
ned and headed back; group 2, those
moderately thinned and headed: group
3. those pruned lightly by thinning on
ly. Since there l. a marked relation
between trunk circumference and the
circumference the greater the total
weight of the tree) measurements of
this character were made at the end of
the third season. Those in group
measured 80 centimeters group 2, 1919
centimeters and group 3, 1873 cent?
meters. or 80 per cent more than the
heavily pruned tree.
Further data is available with regard
to summer pruning young trees. Apri-
cots, cherries, peaches, pears, plums
and prunes were studied. Block A re-
ceived no pruning and the average in
crease of the trunks was rs centime-
ters; Block b received moderate
thinning out and heading back early in
the season and the averagesincrease of
the trunks was 6.5 centimeters; Block
G received moderate thinning and
heading both early and late in the sea
son and the average increase in diane
ter of the trunks was 5.4 centimeters.
From the figures it is evident that
summer pruning at any time is devi
talizing and that midsummer cutting
is more weakening than that done early
in the season. 1t is to be noted that
two comparatively early summer prun-
ings were only little more weakening
than one given late in the growing
period.
In this connection, brief summary
of the manner in which a plant func-
tions will indicate why summer prun-
ing is devitalizing. Early summer
growth is made at the expense of
stored food material and to remove
new leaves before they have had an
opportunity to manufacture and store |
plant food. rob the plant to the same |
extent. After active shoot eongation |
ceases, a plant turns its energies to the |
manufacture and storage of plant food |
for the succeeding year.
1.-The later the pruning is given in
the growing period during which active
shoot elongation is taking place. the
greater will be the plants loss," saws
Bulletin 3l3 of the California expert
ment station.
The above is not to be construed that |
summer pruning is never advisable.
With young Bose pear trees, pinching
back or heading back excessive ter
minal growth will induce lateral growth
which is necessary in the prorer shap-
ing of the tree. Bartletts will respond
in a similar manner. The Anjou had
better be left alone. as it is capable of |
forming a good lateral growth natural
y. No thinning should be given now.
AS a rule, trees one year old give
better results if left alone during the
irst growing season.
With trees that have just entered the
bearing age but are making an exc s.
sive wood growth it may be worth
while to thin out slightly at this time L
)f year. This would be the case with H
.rees where foliage is too dense for
jpur development. AS a rule, however,
me annual winter pruning will accom-
'lish all that is necessary to keep the
rees in proper form.