December 2022 - 8

By Gary Pullano
FGN Senior Correspondent
The impacts caused by a faulty
supply chain continue to bring
significant challenges to agriculture,
including tree fruit orchardists.
The need for alternative trellis
TREE FRUIT
DILEMMA
Trellis post options drive
MSU research effort
Growers are turning to alternative trellis materials due to the difficulty in obtaining
wooden posts used for high-density tree fruit systems. Photos: Gary Pullano
materials took a serious turn more
than a year ago when wooden posts
used for high-density tree fruit systems
were in short supply. The Michigan
Tree Fruit Commission provided grant
funds to Michigan State University
(MSU) to establish demonstration
trials on alternative materials at MSU's
Clarksville Research Center and the
new West Michigan Research Station
in Hart.
Other materials for posts may
include metal, concrete, plastic or
repurposed fiberglass.
Anna Wallis, apple production
specialist for MSU Extension in the
Grand Rapids region, is part of a
project that seeks to identify trellis
material options for growers. Wallis
presented an update on the endeavor
during grower field days in the
summer and fall, the latter on Nov. 1
at the Hart facility.
" I've never done any engineering
work before, but it's been hugely
important, " Wallis said. " We don't
have a magic answer for you yet. It's
been an ongoing process. The most
recent development is we're going to
have a group of MSU students in the
agricultural engineering program
continuing to work on this. "
Wallis learned about the supply
situation a year ago.
" Our supply chain has been
disrupted in so many ways, " she
said. " A lot of people couldn't even
get the wooden posts to install new
trellises. They were hesitant to plant
their orchards this spring. Planting
a high-density tree requires support
immediately. They needed a solution
right away. "
Wallis said that for growers who
could get them delivered, wooden
posts have been expensive. " A lot of
the wood had been converted into
other building needs, especially as
the housing market and other real
estate buildings increased, " she said.
" The cost of wooden posts, which
historically has been much more
affordable than any of the other
materials, was really high.
" We started exploring other options, "
Wallis said. " A couple of distributors
of posts and other material came to
us with other solutions. We filtered
through a few of those and decided to
evaluate some a little bit further.
" We compared everything to wood,
which is the traditional material for
posts, particularly red pine in this
area, " Wallis said. " The things we did
decide to evaluate included the cost of
them, the strength of the materials in
comparison to wood systems. "
Wallis said they worked with Mark
DeKleine at (TrellX Anchoring Systems)
to help evaluate these materials.
" He worked on such things as
altering the spacings between trees so
8 | FruitGrowersNews.com
they would hold a comparable load.
For example, the fiberglass is not quite
as strong and can't bear quite as heavy
a load, so the spacing has to be a little
bit closer. "
Wallis said plastic posts were
eliminated because they are too flexible.
The researchers found that the
fiberglass posts are " one of the more
interesting materials that we've been
looking at. These red fiberglass poles
on the ground are something we've
been looking at. They're usually
a refurbished material - hollow
tubes that are used for applications
like offshore drilling. When they
are compromised in any way, like
a pinhole in them or something,
they can no longer be used for
that application, so they've been
repurposed for things like this. "
The 30-foot tubes were cut in half
and installed in the high-density apple
system. The new block consists of Aztec
Fuji on Geneva 11, spaced 2.5 feet by 10
feet. It now has rows with fiberglass and
steel posts, testing how well each holds
up in high-density orchards.
The steel posts, manufactured
by DeKleine, are used extensively
in Washington, primarily because
of cost, which includes the actual
material and the shipping to get them
here, " Wallis said.
The diameter and the thickness of
each of the materials was analyzed. A
design was developed based on the same
number of wires, the equivalent loads
that the system would be bearing and a
recommended spacing for those materials.
Calculations were made based on
the foot length of the rows. The system
requirements are based on how many
posts are needed based on the length
of the row.
" The final material that we wanted
to look at this year but couldn't get is
a cement post, " Wallis said. " We may
be able to get some next year. They
are manufactured in Italy. They are a
proprietary product that have coiled
wire on the inside that provides some
flexibility and strength. Those are
shipped from Italy and there is one
distributor in the northeast. It requires
some special handling because they are
extremely heavy. We're just learning
about all of those factors.
" So far, we've seen that there are
more comparable price points than
what we expected because some of
these materials are quite expensive, "
Wallis said. " Considering the increase
in cost of the wooden posts, they're
more comparable. "
MSU's John Bakker, who had been
the interim on-site manager at the
Hart facility before retiring, has been
involved in the trellis project.
" I was excited about fiberglass, mostly
because of cost, " Bakker said. " We
were told to put these at 12 or 16 feet.
Based on the price of the material, that
sounded like a good, solid alternative. "
A consideration to be further
explored is how to attach wires to a
non-wood post, Bakker said.
" With a wood post, you can pound
a staple in or use other easy ways to
attach your wires to that. How do we
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December 2022

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