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A good fruit tree should not make a good shade tree. However, when
pruning is neglected, many apples and pears become better shade
producers than fruit producers. Standard-sized trees often outgrow
the reach of ladders or pruning hooks. Backyard and commercial growers
have come to prefer dwarf or semi-dwarf trees, which are not as
tall and are easier to prune, spray and harvest without the use
of ladders.
A
neglected but otherwise healthy tree will usually show a marked
improvement in fruit quality as a result of pruning. Fruit buds
begin developing in the growing season previous to the one in which
they mature into fruit, and more are initiated than can be fully
developed into fruit. Growing conditions during the season of bud
initiation and the subsequent winter will affect the number of buds
which flower, and certain cultivars are "alternate bearers" that
seldom initiate many buds during a year with a heavy fruit crop.
In any case, by late winter the buds for the coming summer's crop
will be very evident. Buds only appear on two or three year-old
twigs or spurs which are no thicker than a pencil.
The
primary purpose of pruning is to increase sunlight penetration,
remove less productive wood, and shape the crown into an efficient,
stable form. If left unpruned, the quantity of fruit produced might
be greater, but the quality much lower. Pruning increases fruit
size, promotes uniform ripening, increases sugar content and decreases
disease and insect problems by allowing better spray coverage and
faster drying following rainfall. It also allows easier access for
timely harvesting. The following points apply to pruning all fruit
trees:
1.
Prune late in the dormant season to minimize cold injury.
2.
Prune heavily on neglected trees or vigorous cultivars, less so
on less vigorous cultivars.
3.
Make all heading back cuts just beyond a bud or branch.
4.
Make all thinning cuts just beyond the base of the branch being
removed.
5.
Avoid pruning too close.
6.
Don't prune a "shade tree" back to a fruit tree in one year. Spread
the thinning over several years.
7.
Wound dressings are unnecessary for trees pruned in dormant season.
8.
Match pruning tools to the size wood being removed. Use hand shears
for small twigs, lopping shears for medium branches, and a saw for
larger limbs.
Visualize
a tree as seen from above without its leaves. Branches radiate out
from the trunk like the spokes of a wheel. In order to allow sunlight
and spray penetration, and to allow access for harvesting, it is
necessary to thin out some of these "spokes." Be particularly attentive
to the following when pruning fruit trees:
A:
Suckers or watersprouts are vigorous vegetative shoots which drain
nutrients needed for fruit production. They often appear at the
base of grafted trees or in crotches and sites of previous pruning
cuts.
B:
Stubs or broken branches result from storms, heavy fruit loads or
improper pruning. Diseases and insects may enter the tree at these
sites.
C.
Downward-growing branches develop few fruit buds and eventually
shade or rub more productive scaffold branches.
D. Rubbing branches create bark injury which also invite insects
or disease. Head back or remove the less productive of the two.
E.
Shaded interior branches develop less quality fruit and limit access
for harvest.
F. Competing leaders result when suckers or branches near the top
of the tree are allowed to grow taller than the uppermost bud of
the trunk or central leader. Head these back or an unbalanced, structurally
unsound tree will develop.
G.
Narrow crotches occur when a branch develops more parallel than
perpendicular to the trunk or limb from which it originates. As
each grows, bark trapped between the two interferes with the growth
of a strong joint.
H. Whorls occurs when several branches originate at the same point
on the trunk or limb. Joints are weaker there, so select the best-located
and remove the others.
I. Heading back or growth diversion cuts are used to limit or redirect
the growth of the central leader or branches. For limiting, cut
back to a weak bud or lateral twig; for diversion, cut back to a
bud, twig or branch oriented in the preferred direction.
Backyard
trees are rarely over-pruned; inexperienced growers often under-prune
for fear of damaging trees. "Topping" or shearing a fruit tree is
about the worst thing that can be done, but even that may result
in better fruit for a year or two. Ultimately, shearing will produce
a dense crown that inhibits access for sunlight, sprays and harvest,
inviting weak structure and breakage.
Adapted
from Pete Lane, Ohio State University Extension, 2000

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