Experimenting with Strawberries
Strawberries are a relatively new addition to the crop mix at the nearly 100 year old Pine Tree Apple Orchard on the shores of Pine Tree Lake near White Bear Lake in Washington County. And although the approximately 16 acres of strawberries make up only a small portion of the 150 acre orchard, the berries play an important part in the marketing and production strategy for the second generation of Jacobsons who have owned the farm. 
“We sell the berries through u-pick, ready picked, and through our on-farm bakery,” says Bill Jacobson, who manages the farm in partnership with his siblings and his parents. “It’s all on-farm marketing.”
One of the more challenging aspects of strawberry management is weed control. That is because cultivation is difficult in the perennial beds and because the approved herbicides available for chemical weed control are becoming increasingly limited. Bill Jacobson, who manages strawberry production at Pine Tree, thinks that no-till planting and post harvest bed renovation of strawberries have promise as weed control strategies. “I saw the no-till renovation up in Ontario at a North American Strawberry Growers Association meeting and I was really impressed with what was being done and decided to try it here,” he says.
Bill thinks the no-till renovation and planting is making for healthier plants. It may even be extending the life of his berry beds. He’s got a planting of Jewel variety strawberries that was managed with no-till that he’s convinced will produce fruit into the fifth, and possibly the sixth, year after harvest.
“Last year we had two fields of Jewel strawberries right next to each other in almost the identical soil,” he says. “The difference in the way they handled the heat and the amount of rainfall we had was night and day. You couldn’t believe it. I’m sure the biological activity in the soil is much better in the no-till planting. We’ve picked that planting for four years and normally it should come out but it was too good last year. The plants were knee high and extremely vigorous. I thought I would be crazy to take those out. If I can turn those into even more of a perennial crop, it would be fantastic. If we can get six or seven years out of a planting that would be great.”
“To grow 16 acres of strawberries, you need to probably triple the amount of land that you have,” he says. “Once we get out of strawberries, we’ll work the ground and put in sudangrass or alfalfa. We’ve got a couple of neighbors who are into horses so they lease the land or we trade land back and forth and plant alfalfa. It seems to be a pretty good rest crop.”
The alfalfa will stand for a few years and then be plowed down. Before going back into strawberries, however, Bill will plant sudangrass, rye, or a mixture of oats and field peas. The object is to control weeds and build organic matter. Recently, he’s experimented with canola.
“We’ve been working with the University of Minnesota on trying some canola in our plantings,” Bill says. “We didn’t have a good take and we tried to overwinter some and it didn’t work very well. The sudangrass is a plow down but with the canola we were thinking we’d plant right into the stubble. It has some allelopathic properties to inhibit weed germination.” Resting a field, by planting alfalfa and plow down crops, breaks the weed and disease cycles.
Alternatives
Bill continues to experiment on alternative weed control strategies. In addition to working with the University of Minnesota on the canola experiment, Pine Tree has also participated in a study to look at the benefits of a wool felt mulch to hold down weeds. The wool mulch project, which as conducted in cooperation with the University of Minnesota and the Agricultural Utilization Research Institute, provided good weed control and an environment for daughter plants to root. The wool was, however, too expensive.
Like most other strawberry growers, Bill struggles not only with weeds but with tarnished plant bugs 
and clipper weevils. In the last year or so, he’s seen a new pest arrive on the scene. “The cyclamen mites are coming on,” he says. “I used to just read about them in the literature from other states but now we’ve seen some here.”
Scouting and economic thresholds are not hard and fast rules. They are guidelines for a farmer, who is the one paying the bills, to make management decisions.
“Integrated pest management kind of turns into integrated farm management which then turns into integrated life style management,” Bill says. “There’s a lot of things going on the whole farm that would effect your decision to spray or not to spray and it’s the same with your life. Your threshold for tarnished plant bug on Friday is way different than Monday. Maybe you’ve got a family and you’re supposed to go to the lake for the weekend so if you cross the threshold on Friday, you’ll pull the trigger then because you can’t baby-sit the strawberries over the weekend. If you reach in on Monday, you just might decide to watch it until Tuesday or Wednesday. A lot of things enter into your decision.”
Bill gets assistance in his scouting and integrated pest management programs from the University and Minnesota Department of Agriculture entomologists who are often visiting his farm. He says the cooperative research projects that those institutions do at Pine Tree are excellent learning tools. He also believes in the value of producer associations such as the North American Strawberry Grower’s Association.
“What if you were in the mortgage business and could only write one mortgage a year,” he asks. You’d know diddly about mortgages. But that’s the way it is with strawberries. You only get one crop a year. That’s why the associations are so critical. I can go to the national meeting and talk to a lot of people and come away with maybe ten years worth of experience.”
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This article is one in a series which can be found in “A Bountiful Harvest: Minnesota Fruit and Vegetable Growers Manage Pests,” Sept., 2002. The publication was produced by the Minnesota Department of Agriculture (MDA) with funding provided by the U.S. Environmental Protection Agency, Region 5, Chicago, IL. For the entire article please go to the MDA’s web site at:
http://www.mda.state.mn.us/ipm/fandvipm.html