ILLINOIS TREE SPECIFICATION REVIEW COMMITTEE REPORT
I. Nursery Propagation, Growing, Harvesting & Handling
A. Impact of Liner Production Practices on Finished “Package”
1. INTRODUCTION
In order to grow quality trees, it is important to start with quality liners. Grading
is the process used to determine the quality of the liners. Sometimes grading
occurs in the field. Most often grading occurs after the liners are harvested. Bare
root shade tree liners should be graded for size (caliper and/or height) as well as
overall quality of the roots, trunks and tops. More details follow.
2. ROOTS
Structural Roots
Liners should have several lateral roots spaced evenly around the trunk to provide support so
the trees don’t blow over in the wind (photo #1). A lack of lateral roots can cause problems
with newly planted liners (photo #2) as well as larger trees (photo #3).
Fibrous Roots
Liners should have as many small roots as possible (photo #4). These roots are key to the
uptake of sufficient water and nutrients. Fibrous roots can be achieved by root-pruning, undercutting or transplanting at any stage of production. Often, root-pruning is done on bare root
liners by pruning the ends off of the roots prior to planting (photo #5).
J” Roots
“J” roots are most often the result of how the liners were planted in the field. They
can be caused by a mechanical planter or wet field conditions when all or most of
the roots, including the structural roots, are dragged to one side. The resulting root
structure is shaped like a “J.” “J” roots may not provide enough support or stability. (photo #6).
Two-Sided / Flat Roots
Two-sided root systems are most often the result of liners that were planted too
close together, or liners that were left on the same spacing for too long before
being transplanted. The tops of these liners also tend to be two-sided or flat (photo #7).
Circling / Girdling Roots
Circling roots are roots that grow in a circle around the trunk or around other
roots. They are often the result of liners that were at one time grown in a plug
or container. Circling roots may eventually kill the tree (photo #8).
1 – Illinois Nurserymen’s Association – www.ina-online.org
Torn / Broken Roots
Torn or broken roots are often caused by the digging machine used to harvest the liners
(photo #9).
Prior to planting, these roots need to be pruned back to the point at which they were
torn or broken. The larger the damaged root, the greater the potential for future problems.
The liner may not be left with enough structural roots or the tear may extend up the trunk
causing damage to the root crown or root flair.
3. TRUNK / CENTRAL LEADER
The trunk should be as straight as possible.
The base of the trunk should not have a large pruning cut from re-growing the top. A large
cut may not close quickly or properly and may provide an entry point for insects and
disease (photo #10).
The cut made when re-growing the top should not be excessively far from the major structural roots.
The “shank” that results from this procedure is then minimized, producing a straighter, better looking
trunk. Additionally, having a shorter shank at a consistent height above the structural roots will help to
ensure that the liners are consistently planted at the correct depth, not too low or too high (photo #11).
The central leader should be alive. If topped, there should be no canker, insects or disease under the tape
often used to train the new leader. (photo #12)
The trunk should have no visible cankers and no major damage from poor pruning cuts
or poor handling practices.
4. BRANCHING
The branches should be evenly spaced around the trunk without excessive gaps
between the whorls. This helps to ensure that the tree will have good branching on
all sides. It also allows for flexibility in pruning to the desired clear trunk height (photo #13).
Sometimes the branching tends to be two-sided or flat if the liners were grown too close together
(photo #14).
Ideally, there should be no branches around the central leader with tight crotch angles.
If there are, they should be pruned out to avoid multiple leaders (photo #15).
Some liner producers differentiate between “branched” and “light branched” liners. Light branched
liners are typically defined as having fewer and/or shorter branches, most often on one side only.
They are positioned as a more economical alternative (photo #16).
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5. GENERAL
When the liners are shipped, they are usually tied together in bundles.
The bundles should be tied in such a way as not to make cut marks on the trunks or roots,
or cause the trunks to be bowed.
The roots should be kept moist. They should not be allowed to dry out during rading or
shipping, or prior to planting.
The roots, trunks and tops should be free of molds, insects and diseases.
The buds should be tight and not breaking.
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Photo #1
TRUCTURAL ROOTS
Red Sunset Maple
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Photo #2
EWLY PLANTED LINERS
Roots of first tree in row (at left)
that is standing straight.
Roots of second tree in row (at left)
that is leaning.
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Photo #3
5” Accolade Elms
Roots of Leaning Accolade Elm (above)
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Photo #4
IBROUS ROOTS
Green Mountain Sugar Maple
Autumn Purple Ash
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Photo #5
IBROUS ROOTS
Autumn Blaze Maple
New root growth after pruning bare root liners.
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Photo #6
ROOTS
Autumn Blaze Maple
Accolade Elm
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Photo #7
WO SIDED/FLAT ROOTS
Patmore Ash
Norway Maple
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Photo #8
IRCLING/GIRDLING ROOTS
Autumn Blaze Maple
Ginkgo
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Photo #9
ORN/BROKEN ROOTS
Callery Pear
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Photo #10
ARGE PRUNING CUT FROM RE-GROWING TOP
Homestead Elm
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Photo #11
HANK
3” Shank
(Preferred)
6” Shank
Red Sunset Maples
(Both from same group of liners.)
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Photo #12
ENTRAL LEADER
TAPE
Triumph Elm
Buds at top of leader failed to break.
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Photo #13
RANCHING
Autumn Blaze Maple
Branches are evenly spaced around trunk.
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Photo #14
RANCHING
Crimean Linden
• Branches are evenly spaced between whorls.
• Branching tends to be two-sided/flat.
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Photo #15
RANCHING
Red Sunset Maple
Branches around central leader have tight crotch angles.
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“
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Photo #16
RANCHED” LINER
(PREFERRED)
“
IGHT BRANCHED” LINER
Autumn Blaze Maples
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Illustration #1
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