East Lansing, Michigan
May 24, 2007
Michigan growers may be able to
expand into new markets, thanks to research being conducted by
scientists at Michigan State
University (MSU) who are developing guidelines and
recommendations for growing a variety of horticultural crops
under cover in greenhouse-like structures called high tunnels.
High tunnels are used in many parts of the world to increase
crop quality and yield. The relatively low-cost, non-heated
plastic-covered structures originated in the United Kingdom for
use in growing berry crops and could potentially be used here to
grow a variety of horticultural crops.
Though fruit and vegetable crops have traditionally been grown
in orchards and fields without protective covering, high tunnels
provide an intriguing alternative for producers looking for
innovative and efficient ways to protect their crops from
weather and insects and extend the growing season.
Tunnels protect crops from frost, rain, wind, hail, insects and
disease, and they can help lengthen the growing season by
allowing harvesting to start earlier in the year or extend later
into the fall. One disadvantage to the structures is that the
plastic has to be removed during the winter because the frames
can not withstand more than a few inches of snow.
“High tunnels eliminate exposing plants to the elements, which
helps to improve crop quality. Secondly, the tunnels trap heat
so that the growing season can be extended,” said Eric Hanson,
MSU professor of horticulture and one of the project’s lead
researchers.
“This research is the first of its kind to be conducted on high
tunnels in Michigan,” he added. “It came about because more and
more growers around the world have been shifting to this
technology, and research needed to be done here under Michigan
climate and environmental conditions to see how they perform.”
Tunnels have been used extensively in California for many years
to grow strawberries and raspberries, and a number of growers in
the eastern half of the United States have also switched to
using tunnels for growing produce and greenhouse plants. Though
a small group of Michigan producers have transitioned to tunnels
for growing vegetables, cherries and berries, a number of
questions exist.
Hanson said that one of the first questions that needs to be
answered is whether producers can justify investing capital in
the tunnel structures.
“Growers need to know up front if they can make money by using
tunnels. Though the structures are relatively inexpensive over
the long term, the initial $25,000 to $40,000 per acre
investment is rather significant,” he said. “We also need to
study and develop sustainable production practices for growing
crops under cover in Michigan and be able to advise growers
about what they need to do differently than if they were growing
crops in a field or orchard.”
Two high tunnels were constructed at MSU research stations in
2005 under a cost-sharing agreement with Haygrove Tunnels, the
leading producer of high tunnels in the United Kingdom. Sweet
cherry studies are being conducted in the structure put up at
the Clarksville Horticultural Experiment Station (CHES). The
second, larger one was built at the Southwest Michigan Research
and Extension Center (SWMREC) near Benton Harbor. This site is
being used to study vegetable, cut flower, berry and sweet
cherry crops. Though a few plants were grown under cover the
first year, 2006 marked the first full growing season.
In this short time period, MSU researchers have already
discovered that fall-bearing raspberries respond favorably to
high tunnels. Hanson said that in addition to increased yield,
researchers found improvement in fruit quality because of
reduced incidence of disease.
“In our first two years of study, raspberries have yielded two
to three times more fruit when grown under cover rather than in
a field. Fruit quality has been better, too,” Hanson said.
“Fruit grown in tunnels is always kept dry, so it is not exposed
to weather elements that can make conditions favorable for
disease.”
Tunnel structures have also shown potential as a consistent and
reliable alternative for organic producers and those who no
longer want to rely on chemicals for managing insects and
diseases.
“Plastic covering appears to minimize many diseases and insect
pests,” Hanson said. “Some types of insects don’t like to live
under plastic coverings, so using the tunnels may provide
protection against these insects. Being able to do away with
chemical-based insect control will eliminate a major expense for
growers and greatly reduce the negative environmental
consequences that can result from chemical use.”
The tunnels seem to protect against Japanese beetle, a serious
pest in and around the CHES and the SWMREC. Though researchers
observed that beetles fed heavily on cherries and raspberries
grown outside the tunnels, little damage was observed on the
tunnel-grown plants because the insects avoided entering the
tunnels.
Plans for the 2007 growing season include planting more
varieties of blackberries to see how they perform and assessing
the cherry fruit harvested from trees planted two years ago at
the SWMREC. Work will also continue on establishing best
production practices with fresh market tomatoes, such as
irrigation and fertigation, a trickle system irrigation system
with fertilizer added.
Even though researchers are still in the early stages of their
project, they are optimistic that they should be able to offer
growers crop recommendations and science-based production
practice recommendations within the next three to four years.
“Findings from this project will ultimately provide growers with
a comprehensive assessment of how crops perform under high
tunnel structures in Michigan and help growers make informed
management decisions,” Hanson said. “From the tunnel’s impact on
crop selection to yield to harvest season to pest and disease
management, this work will help growers answer key questions
about the economic and sustainable production advantages of
using high tunnels.”
Project GREEEN (Generating Research and Extension to meet
Economic and Environmental Needs), Michigan’s plant agriculture
initiative at MSU, has provided funding for Hanson’s research.
Founded in 1997, Project GREEEN is a cooperative effort between
plant-based commodities and businesses together with the
Michigan Agricultural Experiment Station, MSU Extension and the
Michigan Department of Agriculture to advance Michigan’s economy
through its plant-based agriculture. Its mission is to develop
research and educational programs in response to industry needs,
ensure and improve food safety, and protect and preserve the
quality of the environment.
To learn more about Michigan’s plant agriculture initiative at
MSU, visit
www.greeen.msu.edu. |
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