In this Issue:
GUEST ARTICLES
Why Use High Tunnels in minnesota?
USDA-Farm Service Agency County Committee Election
VEGETABLE NEWS
STRAWBERRY NEWS
Using Computer Models to Time Fungicide Sprays in Strawberries
APPLE NEWS
Weekly Trap Counts: June 27 - July 7, 2005
REMINDER: Apple Maggot Emergence Has Begun
| Vol 2 No.9 | July 11, 2005 |
Why Use High Tunnels in Minnesota?
David Wildung, North Central Research and Outreach Center, Grand Rapids, University of Minnesota
It has been said that Minnesota has no spring. Weather in April and May can be very unpredictable with the potential for frost that can damage tender vegetable transplants. Indeed, frost can occur in northern Minnesota well into June. At the same time that the frost danger is so great in April and May, the day length is increasing and the sun angle is near its highest, making conditions optimum for plant growth and development. High tunnels offer growers a way to capture some of the light and heat from these long days. It is not uncommon during a sunny early May day when the air temperature is in the low 50‘s to have the temperature inside the high tunnel well over 80 degrees --optimum for plant growth and establishment. High tunnels enable growers to start tender warm season crops in an environment that is less threatening and easier to protect from frost.
A high tunnel, by definition, is a non-permanent structure that has no electrical service, no automated ventilation and no heating system. High tunnels typically are ventilated manually by rolling the sides up or down as needed using a roll bar. They are covered with a single layer of 6-mil greenhouse plastic that is left on the structure year around and normally will last two to three years. Frost protection in the spring and fall should be available and typically can be provided by heavy row covers or, more reliably, by standby portable propane heaters.
The Minnesota High Tunnel Project started in 2003. During the 2003 and 2004 growing seasons great contrasts were seen in growth and production between the high tunnels and the field. The benefits of high tunnels in Minnesota were never more evident than during the 2004-growing season when there were frosts 13 days in May, a frost on June 16, and another frost on August 20 all affecting field plantings. High tunnel production both seasons was significantly earlier (up to 7 weeks earlier), greater, and resulted in tomato fruit that was larger and of better quality than that produced under field conditions.
In addition to the yield factors, high tunnel production has several other noticeable benefits over field production. Because of the earlier planting date and better growing environment in the high tunnels, it is possible for the grower to provide a steady amount of good quality product to the market for a longer period of time. High tunnel production is more predictable and dependable than field production, making market planning easier. During the 2004 season, customers frequently asked when tomatoes would be available. High tunnel tomatoes were available much earlier than field ripened tomatoes and at a time that was very close to when ripe fruit had been available during the 2003 season.
Another factor in high tunnel production was the reduced occurrence of insect and disease damage. Tomatoes have been grown without septoria or early blight symptoms in the high tunnels, whereas, by late August these diseases had killed nearly all of the field-grown plants. Aster yellows, which infects carrots grown in the field, was not a problem in carrots grown in the high tunnels. Radishes grown in the field are usually infested with root maggots, and they were not bothered by maggots in the high tunnels. Reducing these insect and disease factors led to less pesticide use as well as better, more dependable production.
A third noticeable advantage in high tunnel production is cultivar selection. Often in Minnesota, a grower selects a cultivar for field production because it matures earlier than others, even though it may not have the yield potential of cultivars developed for regions with longer growing seasons. High tunnels allow growers to not only grow these earlier-maturing cultivars for their early crop, but also allows the opportunity to maximize production by choosing longer-maturing, full-season cultivars. For example, the tomato cultivar ‘Cobra’ produces few ripe fruit in the field under northern Minnesota conditions; however, under high tunnel production it is capable of producing up to 20 pounds of good quality fruit per plant.
High tunnel production is different from field production in that the grower has more control over water, fertility, and temperature levels. The grower can monitor these factors and to choose which cultural practices to implement. There are also different levels of management and culture within the high tunnel. One grower may let the tomato plants grow on the ground in a matted row system where another grower may tie the plants to stakes or trellis the plants and prune them as they develop during the season. Whichever the growing system or environmental factors used, careful and more-detailed management is necessary in the high tunnel.
World wide, the greatest success with high tunnels has been in regions where growing seasons are somewhat marginal either being too cool or too short. In Minnesota, the growing seasons are both too cool and too short, making the potential value of high tunnel production unlimited.
During the 2005 growing season high tunnel production systems are being evaluated at the Staples Ag Center in Staples and at the North Central Research and Outreach Center in Grand Rapids. You are welcome to visit either of these research locations. At Grand Rapids both determinate and indeterminate tomato cultivars are being evaluated using single or double trickle irrigation systems and with black or red plastic.
Field Day at Grand Rapids
A field day at Grand Rapids is planned for Wednesday, August 31st. Contact us for more information at: dwildung@umn.edu
Related References
Minnesota High Tunnel Production Manual for Commercial Growers
The price for the manual is $35.00.
Make checks payable to:
MFVGA
Mail check to:
The Minnesota Fruit and Vegetable Growers Association
15125 W. Vermillion Circle NE
Ham Lake MN 55304
Phone:763-434-0400
e-mail: mfvga@worldnet.att.net
High Tunnel Production Manual, 2003 (From Pennsylvania State University)
The price for the manual is $25.00.
Make checks payable to:
The Pennsylvania State University
Mail check to:
Dr. Bill Lamont
Department of Horticulture, 206 Tyson Building
The Pennsylvania State University
University Park, PA 16802
Website: http://plasticulture.cas.psu.edu/manual.htm
Dr. Dave Wildung is Professor of Horticulture, conducts research on several of vegetable crops, as well as blueberries, strawberries, and several ornamentals.
ACKNOWLEDGEMENTS
Co-Editors: Bill Hutchison (hutch002@umn.edu), Department of Entomology, University of Minnesota, Jeanne Ciborowski, Minnesota Department of Agriculture, Ag. Resources Management and Development Division, and Suzanne Wold-Burkness (woldx018@umn.edu), Department of Entomology, University of Minnesota
The Newsletter is published weekly from May through August, cooperatively, by the Minnesota Department of Agriculture (MDA) and the University of Minnesota (U of MN). Reports are posted on the U of MN and MDA web sites on Fridays. If you have suggestions and/or comments, please send your contributions by 4 p.m., Wednesday to Jeanne Ciborowski, 651-297-3217, jeanne.ciborowski@state.mn.us , MDA, 90 W. Plato Blvd., St. Paul, MN 55107-2094. You can access the Newsletter at the U of MN web site in htm format at: www.vegedge.umn.edu/MNFruit&VegNews/mnindex.htm and at the MDA web site in pdf format at: www.mda.state.mn.us/biocon/fruitreports/
Partial funding for this publication is provided through partnership agreements with the Minnesota Fruit and Vegetable Growers Association (MFVGA) and the United States Department of Agriculture – Risk Management Agency (RMA). These institutions are equal opportunity providers.
DISCLAIMER
Reference to products in this publication is not intended to be an endorsement to the exclusion of others which may have similar uses. Any person using products listed in this publication assumes full responsibility for their use in accordance with current manufacturer directions.
The University, including the Minnesota Extension Service, is an equal opportunity educator and employer. ©1999-2005 Minnesota Extension Service, University of Minnesota. All rights reserved. Contact copyright@extension.umn.edu for information on reproduction or use of this material.