More Berries, Less Chemicals

The Berry Patch is a 120-acre farm near White Bear Lake, in Washington County. Kevin Edberg is the primary farmer, with other members of the seven family farm partnership participating in financial record keeping and machine repair. The families have been partners in the farm for 25 years.
The Berry Patch generally has five acres of strawberries, approximately eight acres of blueberries, six acres of summer and fall bearing raspberries, up to 50 acres in rye, and between 20 to 40 acres in oats and field corn. Corn is grown on land rented by the Berry Patch to a neighbor.

In years past, the farm grew vegetables, including pumpkins and asparagus, but only fruit and small grains are grown now. The grains are grown for their straw mulch. All marketing is done from the farm, either through a u-pick operation or from picked fruit sold on the farm. Kevin says the u-pick fruit comprises between 75 to 80% of farm fruit sales. Some rye straw is sold to other fruit growers but most of the straw crop is used on farm.

IMP Practices

The strawberry crop has a six year rotation that included the small grain, most likely rye, and a short lived Sudan grass plow down. Kevin likes to keep a field out of strawberries for at least a year and a half. “Mostly we’re going for tilth and contributing to weed control with the rotation.

On the light sandy loam to sandy soils that make up the farms largely flat fields, Kevin says he has a few problems with strawberry disease that rotations might affect. “We try to plant a crop of strawberries one year and take a crop in years two through four,” he says. “After the third harvest we’ll go in there and, depending on the weed pressure that’s there, we’ll do either a selective or broadcast spray of Roundup to get rid of accumulated perennial weeds. “ The farm’s main perennial weed pests are quack grass, Canadian thistle, and a smattering of other thistle species.

“Then we’ll try and put in a crop of Sudan grass to finish out the growing season. That would go in sometime in July and I’d let it grow until sometime in early September when we plow it down,” Kevin says. “The Sudan grass has a negative effect on nematodes and is a good weed smother crop. It also provides a little organic matter.”

Following the Sudan grass plow down, winter rye is planted. “We take that to grain the next summer and use the rye straw for mulch. The rye also allows us to take advantage of the allelopathic effect of rye to discourage weed seed germination,” Kevin says.

The rye planted at The Berry Patch gets five or six feet tall, according to Kevin, and also has a smothering effect on weeds. “It’s a common rye grown in our neighborhood,” he says. The rye is combined and baled in late July, or early August. “After we take off the rye we let that grow back a little bit and then scout for perennial weeds. We’ll spot spray those areas with herbicide using a backpack sprayer or a sprayer tank behind the tractor,” Kevin says. “Our goal is to get all the perennials out prior to planting strawberries.”

Crop rotations may have some impact on insects and disease but Kevin relies on a number of other primary strategies to hold them in check. He uses no fungicides on raspberries and blueberries. He does use a limited amount of fungicide on strawberries. “I will go in and make an automatic fungicide application at about ten percent bloom and then, if the weather stays dry, we may not make another one,” he says. If the weather is wet during bloom, I definitely will make a second spray application during bloom: usually seven to ten days after the first one. We’re going after botrytis. The idea is to prevent initial infection of the flower. If you do that, you can virtually eliminate you problem with infection during the harvest period. If you protect your blossoms, you don’t have to worry about your fruit.”

To further reduce fungicide applications, Kevin bands the spray so he’s applying the chemical to the plant rows and not the aieles. “By banding and scouting, we’re able to put less insecticides and fungicides out into the environment. It has some economic impact because with banding I’ve cut my spray costs by 50%,” Kevin says.

To keep his insecticide applications to a minimum, Kevin scouts his strawberry fields two or three times a week from just before blossom time until early fruit set. “I’ll sample each field by randomly choosing five or six locations and then look at five or six blossom clusters,” he says.

“It seems to be about 50% of the time we’ve not had to spray at all or some fields don’t get sprayed and others do,” Kevin says. “It may depend on the acreage of the field, how weedy they are, and how many years they’ve had for trash to build up.”

Kevin doesn’t use insecticides on his blueberries or raspberries. He’s never seen a sign of disease of insects on the blueberries. He isn’t sure if that’s because there are so few plantings in Minnesota that disease and insects haven’t yet built up or if it’s due to his varieties. The majority of his blueberry planting is made up of the Northblue variety with some North Country as a pollinator. The blueberries are pruned every three years.

Disease and insect management in the raspberries are part of an overall management plan that includes weed, risk, and labor control as well. Variety selection in raspberries and strawberries doesn’t play much of a role in Kevin’s IPM program. He focuses on vigor, berry size, and hardiness in his raspberries.

Kevin, whose farm is rich in mulch from his rye and oat crops, is convinced that heavy mulching gives his strawberry varieties a boots by moderating soil temperatures, suppressing weeds, and retaining water. He’s fond of grain straw mulch over strawberries but he prefers wood chips and saw dust for blueberry mulching.

“Mulching is one of the most underrated projects that we do,” Kevin says. “If we did a better job of that we wouldn’t have so much of the other issues such as weed control and water management. We’d have healthier plants. The mulch reduces the likelihood of disease organism getting into the strawberries. “

Kevin’s use of IPM strategies does result in an economic return. He estimates that it may save him up to $100 per acre in chemical costs. But that’s not a significant cost reduction when the overall crop may be worth as much as $5,000 per acre. He says he just feels better because he’s reducing the amount of fungicides, insecticides, herbicides, and fertilizers he’s putting out into the environment.

“We’ve got this 20 acres here and we’ve got this biology that seems to be working,” he says. “We’ve got wild turkey and pheasants. We had an eagle last season. We’ve got deer (probably too many) and we try to promote to out customers that when they buy from us they are contributing to the maintenance of green space and wildlife habitat.”

Kevin says he gets particularly excited when he can stand and watch 20 to 30 wild bumblebees pollinating the waxy flowers. He thinks they nest in the undisturbed soil in, or near, his pine and maple windbreaks!

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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