MN Fruit & Vegetable IPM News - Vol. 1, No. 7

Gary Pahl, along with his brother Brian, operates Pahl's market, a fourth generation family operated vegetable farm, in Dakota County just south of the Twin Cities. The farm consists of 1,000 acres of vegetables including sweet corn, cabbage, pumpkins, green beans, winter squash, tomatoes, and cucumbers and dill. Handling field harvested crops is done in a cooling and packing line. The farm has temporary refrigerated storage for up to four semi loads of produce. "We ship the produce as quickly as we can," Gary says.

Integrated pest management has been adopted as a tool on the Pahl's farm over the last decade. Gary sees IPM as a way to increase farm safety for farm workers as well as owners and to reduce inputs in a thoughtful way that doesn't risk quality.

"My definition of IPM is somebody who goes in and scouts and sprays for a specific pest at a particular time when the threshold reaches a certain level," he says. "By carefully observing and not spraying until you reach a threshold that could cause problems you can do the best job on the pest itself and alleviate the highest risk for everybody else."

Scouting is an essential part of IPM at the Pahl's. "As an example we set traps out for corn borers," Gary says. "We scout one time a week when we know there shouldn't be that high of an infestation but in the fall when you get your second flight in and you start scouting for corn ear worm we're scouting at least twice a week." That regular contact with the crops and the fields allows labor and management to be closely in tune with the cycles of plant and pest development.

"I think when you're spending that much time in the field you can see where the pattern is going," Gary says. "Your timing and kill is a lot better. Timing is everything if you want good control…With good scouting you know when to spray when it's most effective and when not to waste your spray when there's nothing out there." Gary estimates scouting costs between 6 to 12 dollars per acre per season.

Effective and well timed spraying saves on increasingly expensive pesticides. But for a sweet corn grower there are other concerns as well. Guesswork and cookbook style spraying schedules just don't cut it when you need a high quality product. "If we let the corn borer get ahead of us, we not only lose yield but we lose clean product and we have to have clean product," Gary says. "When we have corn for a customer three or four states away and they find a worm they aren't going to take it. It's pretty critical that our corn leaves the field corn borer free."

Gary has tried trapping squash bugs so as to establish a scouting program in his vine crops. He hasn't had much success with trapping them, however. He thinks a cup-like trap using the insecticide, Sevin, may have some promise. He's also experimented with some resistant seed varieties. "They are coming out with some winter squash varieties that are resistant to powdery mildew," he says. "We're using them but the seed cost is more. If you do plant a resistant variety and weather conditions are right for powdery mildew you look like you're pretty smart. But if the conditions aren't right and you wouldn't have had to spray anyway you threw your money away."

One fairly expensive fix, often recommended to IPM and organic farmers, just doesn't work on the Pahl farm. "We tried beneficial insects and they didn't work," Gary says. "Maybe the scale of our farm is too big. We did try them on our cucumbers a few years ago. I don't think they get the pests in a quick enough fashion. Here's the problem. If you release them you have to release them at, say, when your population is 25% of when you're going to start spraying. Then they have to keep up with the hatching larvae of the pest. You need to have the growth of the beneficials match the growth of the pest and if that doesn't work you've got to go in there and spray anyway."

Scouting and spraying are not the only effective tools in the Pahl's IPM toolbox, however. Gary believes a well thought out crop rotation, based on observation and common sense, are basic to sound integrated pest management. Crop rotations are basic to effective integrated pest management. "If you want to be considered a good farmer your rotation practices better be pretty sharp," Gary says. Gary has his cole crops on a five year rotation and sweet corn is generally on a two year rotation. Sometimes corn follows corn because nothing else will work in that field for that season.

In the Pahl's rotation they can follow beans with corn or cabbage. They can rotate out of corn into a season of cabbage. But Gary won't follow that cabbage with a vine crop like pumpkins or squash. "If you have pumpkins with black rot and then come back with cabbage you'll find that it's extremely susceptible to black rot," he says.

Green manure and tillage practices are a natural extension of a well thought out crop rotation. The Pahls often follow a harvest with a late summer or early fall planting of rye. The rye will be plowed under in either the spring or the fall, depending on the crop that will be planted after it. When neither rye nor another crop is in the field, the Pahls control disease by plowing under trash and keeping the soil black. "All our fields are extremely clean," Gary says.

Trained and experienced hired labor is also an IPM tool that Gary counts on. In addition to cultivating a couple of times each season the Pahls have about 40 experienced people in the field with hoes. Those hoe-masters do more than decimate weeds. "They're looking for different situations in the field. They might bring in a worm they saw out there and show it to somebody. That's part of their job," Gary says. "These people are experienced and they take pride in what they do.

The Pahls feel that the economic benefits of IPM are important. "IPM practices put you in touch more with your costs and your inputs," Gary says. "It allows you to make better decisions on your inputs. There's nothing you can do about price - you're either going to be selling it at a certain price or you're going to start discing it up, that's a decision each farmer has to make - but as far as knowing the cost of your inputs, IPM allows you a better opportunity to decide where you should be placing your money."

With IPM, Gary Pahl says, you learn to be a better manager because you actually watch the fields and make decisions based on your experience and what you see. Because you manage closer you make decisions such as whether or not to spray or to adjust your spray rate based on the pest level. Because you make decisions like that, rather than just following a set schedule, you develop more pride in your work. Additionally you reduce your exposure to pesticides and increase your control over pesticide costs.

"You spend all that time out in the field and sometimes you think you're wasting money," Gary says. "You're not. You're saving money."

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ACKNOWLEDGEMENTS

Co-Editors: Bill Hutchison, Department of Entomology, University of Minnesota, hutch002@umn.edu
Jeanne Ciborowski, Minnesota Department of Agriculture, Ag. Resources Division,jeanne.ciborowski@state.mn.us
Suzanne Wold-Burkness, Department of Entomology, University of Minnesota, woldx018@umn.edu

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., Tuesday 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/default.htm

Partial funding for this publication is provided through partnership agreements with the Minnesota Fruit and Vegetable Growers Association and the United States Department of Agriculture – Risk Management Agency (RMA) and the RMA Community Outreach and Assistance Partnership Program. These institutions are equal opportunity providers.

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References 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.

Last Revised June 17, 2004.
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