Thoughts from the Organizer
OATS’ own weed control expert, Sam Oschwald Tilton, is the long-time organizer of the Midwest Mechanical Weed Control Field Day - the largest annual gathering of weed control companies and experts in the Midwest. Sam recently hosted the 2023 installment of the event and brings his thoughts and musings to our Organic Perspectives essay series. - Mallory Krieger, OATS Program Director
By Sam Oschwald Tilton, Glacial Drift LLC
Published November 10th, 2023
Like an 8-year old child eagerly anticipating halloween and the ridiculous, gut-busting candy consumption that would make a diabetic faint, so farmers around the Midwest look forward to the Midwest Mechanical Weed Control Field Day, which comes but once a year and features field demonstrations of weeding tools for row crops and vegetables. This year’s field day was in Wooster, Ohio at the end of September. Two hundred farmers and machinery dealers gathered from all over the Midwest and as far as Canada.
Having so many manufacturers, dealers, and users of weeding machines together is always an opportunity to learn a lot. Kurt Bench, an Ohio organic farmer and one of the organizers of this year’s event, set the tone well when he said, “at an event like this you want to learn something, meet someone new, and share what you know.” Before the official start all of the demonstrators were in the demo field calibrating their cultivators. As a former machinery rep and cultivator nut, I enjoyed checking in with each company to see how they adjusted their machine. These reps often know their machines so well that they are able to talk about the field conditions where their tool really shines, and also when it will not be effective.
I caught up with Dale Stumpf from Buffalo-Apache. In cultivator calibration, he stressed making the easiest adjustments first. For him that meant that when his sweeps were not penetrating the ground well, before adjusting gauge-wheels or the pitch of individual sweeps, he adjusted the length of the 3-point top-link, in order to change the angle of all the sweeps at once. Tractor speed is also an easy adjustment to change the cultivator’s aggressiveness - the demonstratorsI talked to seemed to think of 4 3/4 - 5 mph as a good rule of thumb speed that balances accuracy, soil flow, and the need to cover ground. Dale also talked about the importance of sweep design - they want their sweeps to shatter the soil so it flows well and so that clods do not cover a young crop. With large single sweeps in each row, the Buffalo machine is good at not getting clogged with residue and dealing with large weeds.
I left Dale and walked over to Gary McDonald of AccuraFlow as they adjusted their cultivator in young corn. “Our machine uses the flow of the soil to bury weeds in the row, and for that to work we use crop shields as an offensive weapon.” Now here is a man who grabs my attention - talking about cultivator set-up like he is strategizing for a football game. Gary explained that more than protecting the crop from soil, he uses crop shields to meter the amount of soil going into the row in order to bury weeds but not the crop. Whereas the Buffalo cultivator can handle large weeds, Gary acknowledged that the AccuraFlow cultivator is meant for very precise and early cultivation - “once the weeds are up to your knees, you need a different machine. Ours is a keep it clean machine, not a get it clean machine.” The AccuraFlow cultivator has several smaller sweeps for each row - they do a good job of breaking up soil into a flowable stream and directing it accurately into the crop row to bury in-row weeds. Gary took the time to think about the role of finger weeders. They are commonly mounted to toolbars on spring-loaded arms and run behind all of the sweeps, to pull soil and weeds away from the crop row. “I want to bury weeds, so I don’t want the fingers running last, or they pull the soil away that the sweeps hilled up.” For this reason Gary mounts the finger-weeders on the AccuraFlow cultivator in-between the sweeps - so that they can uproot weeds in the crop row, and sweeps behind them can finish the pass by throwing soil into the row. Gary also talked about how tools work together - he likes cutaway discs running ahead of finger-weeders - because the cutaways leave a strip of untouched soil a few inches wide centered on the crop row, which the rubber fingers can then shatter to uproot in-row weeds.
Gary McDonald explaining the AccurFlow cultivator
Whereas the Buffalo and AccuraFlow machines had sweeps that are meant to move soil, there were several European-made machines that work on a different principle. These machines, like Garford, Hatzenbichler, and Einbock, have sweeps that are flat to the ground. Like a razor blade, they move through the soil very shallowly, cutting the top ¾’’ of soil while moving very little soil into the row. Because these sweeps operate so shallowly and move so little soil into the crop row they can be run in wetter conditions (when the top layer has dried out) and when the crop is younger (no soil moving into the row to bury the crop). Because these machines often are not meant to bury weeds in the row, finger-weeders running after the sweeps are crucial to pull out weeds from within the crop row.
A European-style sweep with a very low rake angle - flat to the ground for shallow and early cultivation.
Many of the cultivators were mounted on camera-guided slide hitches, so that the weeding tools stay centered right on the row. Organic farmers are more and more interested in these hitches because they improve the accuracy and speed of cultivation. The price continues to drop (slowly), and the quality of the cameras and ease of use of the system improves. Farmers find these camera-guided machines generally reliable and easy to use. Although, some of the more old-school demonstrators steered their tractors by sight - and I couldn’t argue with the results.
The field day also featured a laser-weeder from Carbon Robotics. This machine autonomously covers fields, night or day, identifying weed and crop by camera and killing weeds by laser. I enjoyed talking economics with the salespeople - the machine costs one million dollars, and so at this point they believe it only makes sense for growers spending $250,000 a year in weeding labor. But over time the cost of the machine will drop and its capabilities will improve. So although it is not applicable for most organic row crop farmers now, it may be in the future, and either way its capabilities are instructive for the future of weeding tools. The tool can be set to different ‘cultivation settings’. Based on farmer feedback, the machine can be programmed for different types of weeding: depending on field and weather conditions, farmers can set the machine to only target weeds of a certain size, or kill weeds of a certain species, or even to thin crop plants.
The field day made clear to me that we have phenomenal tools available to organic farmers for managing weeds. More than a shiny piece of metal, it is crucial that farmers understand their options, and how a machine can fit their conditions and their systems - because more important than the tool is the system that it fits into. The speakers at the morning educational sessions alluded to this in their talks on cultural weed control. I overheard farmers in the afternoon refer to the principles of weed management from the morning as they leaned against giant cultivators, discussing how the type and timing of their tillage would influence next season’s weeds, “I would want to leave a lot of my weed seeds at or near the soil surface over the winter, so that they rot or are eaten, that will take care of them better then a cultivator.” Even after organizing this event for 6 years, this year’s Midwest Mechanical Weed Control Field Day was full of opportunities to learn more about the tools, techniques, and people helpful for weed management.