Daren and Holly Koeppe have been growing agronomic crops, and more recently vegetables, near Sisseton, SD, on the farm where Daren grew up.
Several years ago, the Koeppes decided to reduce the use of pesticides and commercial fertilizers on the farm and concentrate on building soil health. They’re currently in the process of transitioning Koeppe Family Fields LLC to organic production.
“Our family changed eating habits and we try to eat more organic and grow and eat as much as possible from what we raise,” said Holly. “It seemed natural to align our business with decisions for our household.”
For the past two years, the Koeppes had a CSA. This year, they decided to sell at the farmers market in Sisseton.
“The hardest part of having a CSA was so many items had to be ready at one time,” said Holly. “There was more stress in spring when we were trying to plant corn, soybeans and wheat, then plant all the gardens for produce so it would be ready on time.”
The first year, the Koeppes planted everything that would thrive in their region. This year they’re growing peas, green beans, lettuce, bunching onions, spinach, beets, cauliflower, broccoli, cabbage, kale, tomatoes, peppers, cucumbers, carrots, zucchini, potatoes, watermelon and cantaloupe. They’re also growing several types of winter squash including butternut, buttercup and spaghetti, along with edible pumpkins.
The Koeppes wanted to increase the acreage of one or more crops, so this past summer, they participated in on-farm research with South Dakota State University (SDSU). The trial was designed by SDSU Extension to test different weed control methods in green beans.
“Our green beans have grown well for the past few years, so we thought that was something we were making progress on,” said Daren. “It goes with our goal to transition all of our farm ground to organic.”
The equipment needed to sow green bean acreage is minimal compared to other large-scale vegetable production. The Haygrove planter the Koeppes use for row crops is the same planter used to plant the green beans, and the flame weeder they use on agronomic cops can be used for vegetables.
Daren initially used the flame weeder on corn ground undergoing the transition to organic. The weeder, which they purchased from Agricultural Flaming Innovations (AFI) in Nebraska, is widely used by other AFI customers for weed control in organic produce.
Over winter, the Koeppes met with the SDSU team to determine goals and the data they’d collect, including weed management and effect on yield. The Koeppes planted one-half acre of green beans on June 10, which Holly said was late, but successfully helped avoid the bean leaf beetle. However, heavy rain following planting knocked back germination.
Weed control in the trial included hand-weeding, hand-weeding with a cultivation pass, cultivation pass only, flame weeder pass and flame weeder with cultivation. There was also a control plot with no weed treatment.
The flame weeder works by intense heat on vegetative matter. “Green beans are a broadleaf plant and grow from the top of the plant,” said Daren. “If the plant is above the heat source, and the heat can be underneath the top of the plant, the effect is the same. If you hit the top of a broadleaf with heat, that’s where it grows and the heat will terminate the plant – it’s non-selective.”
Any weed growth, even if the plant is in the white thread stage and starting to germinate, will be terminated by the flame weeder. The Koeppes’ goal is to use the flame weeder just prior to bean emergence while they’re still protected under the soil.
Weather conditions influence when it’s safe to use a flame weeder. Dry, windy conditions combined with dead material on the ground is not ideal, so the Koeppes wait for safe conditions.
Daren and Holly Koeppe (and the next generation of growers) are working on transitioning their farmland near Sisseton, SD, to organic. Photo courtesy of Kristine Lang, SDSU
Daren said a pre-emergence flame weeder pass on half of the plot made a world of difference in weed control. Although that disparity disappeared by summer, as plants were first growing, there was a clear difference.
The Koeppes’ primary weed challenges include Canada thistle, waterhemp, pennycress, marestail and grasses such as foxtail. The flame weeder doesn’t destroy grasses effectively, so part of the data collection includes cultivator effectiveness. Although cultivation between rows takes care of some grasses, weeds within the rows are more difficult to manage.
For additional weed management, the Koeppes purchased a 20-foot-wide John Deere rotary hoe this summer, but not in time to use for the green bean trial.
The protections on some of the Koeppes’ land in the Conservation Reserve Program (CRP) expired last autumn, and that land is eligible for organic certification this year. Other portions of the farm are in various stages of transition.
“The land where we grow the produce and did the green bean trial is on its third year, so it should be certified by next year,” said Holly. “We have to have three complete growing years with no prohibited substances.”
This summer, SDSU counted weeds and determined leaf biomass in the various weed control method areas. Although all the green bean trial data have been collected, they haven’t been organized and analyzed yet. So far, it’s clear that the hand-weeding section and the hand-weeding/cultivating section provided the highest yields. The beans weren’t tall enough to flame weed later on during the growing season, but the Koeppes noticed a significant decrease in weeds early where they flame weeded during the pre-emergent stage.
The green beans are being hand-harvested. The weediest areas, including the flame weeding and flame weeding/cultivating sections, will be harvested once, then terminated. However, after more heavy rain, the Koeppes are struggling to harvest this year’s crop. If they find a weed control method that works well for them, they will plant more green bean acreage and invest in a mechanical green bean harvester.
Early conclusions are that more trials will be necessary to determine an organic weed control method that works best. The Koeppes and SDSU are discussing continuing the research next year using the rotary hoe, companion planting with a small grain and more flame weeding passes before planting and at the pre-emergent stage.
In 2026, the Koeppes will plant green beans in a different field. “If we get the weed control method down for green beans,” said Holly, “we would start figuring out a good crop rotation, which will probably lead to more research on different vegetables.”
by Sally Colby
