The continually growing demand for vegetables is benefiting farms in the North Central region, where Michigan, Wisconsin, and Minnesota are three of the top vegetable producers in the country. As tender crops, often the greatest expense in vegetable production is weed control, especially within the crop row. The ways that weeds are managed greatly affects sustainability and profitability. There are several tools for in-row cultivation, some newly introduced from Europe. Midwestern growers have reported high satisfaction with these new in-row tools for certain crops under certain circumstances, sometimes resulting in huge reductions in labor costs. While these tools show great promise, many uncertainties and gaps in knowledge hinder adoption and effective use by growers.
Determine the growth stages of both crop and weed where each tool is most effective Determine which weed species are best controlled by each tool Learn whether certain combinations of cultivators are more effective than individual tools Identify which tool offers the biggest net savings to farmers Identify carrot cultivars that are suited to mechanical cultivation
The most promising in-row cultivation tools evaluated by cultivating carrots. In the process carrot cultivars will be screened for ability to compete against weeds and tolerance to mechanical cultivation. The strengths and limitations of these in-row cultivators will be judged by collecting a wide range of weed and crop survival data. Farmer participation is paramount – tools will be trialed on two nearby farms and we will confer with two expert Consulting Farmers throughout the season. This project will generate useful, farm tested, and detailed observations on the best methods and tools for managing in-row weeds. It will also build on work being done to identify competitive carrot cultivars. This information will be shared with growers and extension educators through field-days, presentations, conferences, an extension publication, and articles. We will evaluate this outreach through follow-up phone calls and surveys in order to track our ultimate goal of enhancing profitability by improving mechanical weed control on the many North Central region vegetable farms.
In-row tools can substantially reduce hand-weeding costs for both small and large vegetable growers. Even tender crops at young growth stages can withstand these tools if they are used properly (we used them on 25 day old carrot with 1 true-leaf). For these tools to work it is essential that the crop be larger than the weeds and that the seedbed have been well-prepared.
The finger weeder appears to work primarily by breaking the capillarity in the row so that the weed roots cannot draw water, and by hilling soil to cover in-row weeds. The finger weeder also worked better in moister soil. The torsion weeder appears to work by uprooting weeds and needs to be set very shallowly (half inch). The torsion worked better in drier soil.
Hilling (even with traditional sweeps) to bury weeds can be a great in-row weeding tool.
We found some evidence that certain cultivars of carrots are more cultivation-tolerant than others – due to larger roots at the time of cultivation certain cultivars showed greater tolerance to those tools that work by uprooting. However our results are not conclusive enough to make recommendations to growers, only to suggest further research.
Farmers are finding success with these in-row tools, the most difficult part is mounting these in-row tools onto existing tractors and toolbars.
Please see our youtube channel for videos of interviews with European farmers and tool manufacturers, and videos describing these in-row tools, and what we learned about how best to use them – MSU Mechanical Weed Control – https://www.youtube.com/channel/UCH-k889oYbUaEznvgiDtrOQ
By generating detailed results on in-row cultivators and carrot cultivars our research will enhance production and profitability on vegetable farms via improved weed control and reduced herbicide use. We will generate and clearly present information on which in-row cultivating tools are best suited to a farmer’s conditions (soil type, crop, prevalent weeds). We will provide an economic analysis for each tool and tool combination so that a farmer can do the math and decide whether one of these tools will pay for itself under their specific conditions. This project will also generate results supporting concurrent research showing the competitive differences between carrot cultivars.
Learning Outcomes –
- Growers and extension educators are aware of the different in-row tools available and international educational resources
- Growers and extension educators understand the strengths and limitations of each cultivator and how best to match specific cultivators to crop growth-stage, weed species, and soil type
- Growers and extension educators understand the importance of cultivar selection for competitiveness and mechanical cultivation
- Growers have the tools necessary to calculate pay-off times for different cultivators
Action Outcomes –
- Growers apply project’s economic results to their own farms to see how different in-row cultivators pay for themselves
- Growers use in-row cultivators in more tender crops and/or younger crops than they have previously
- Growers buy in-row tools and use them successfully to lower weed pressure
- Mechanical in-row cultivation drastically reduces weeding costs, herbicide use, and increases profitability
Which in-row tools either alone or ‘stacked’ are the most effective?
What are the tool’s effects on hand-weeding time and carrot yield?
How does the amount of soil moved by the tool effect weed, carrot death?
Mechanical Weed Control – A greater percentage of carrots are grown organically in the US than any other crop. The hardest weeds to control are those within the row. Newer in-row weeding tools from Europe have become available. These tools are widely used in Europe. But there is little documented experience of these tools in the US. We wanted to trial these new in-row tools and some old ones to see how they can best be used, whether they work better in combination, and their overall promise for growers. We chose to trial the tools in carrots – a slow-growing, tender and popular crop, hoping that carrots would provide a good reflection of the strengths and weaknesses of each tool.
Experiment – Carrots (variety Bolero) were planted on a flat, sandy field at the MSU horticulture farm. We flam-weeded just before emergence, trying to create the greatest size differential between carrots and weeds. Between-row tools were run along with handweeding to create a weed-free field. Mustard and Millet seeds were planted about 16 days after carrot planting (DAP) to act as representative weeds.
About 23 DAP, when the carrots had one true leaf and the weeds were cotyledons, in-row tools were run through the carrots. Weeds and carrots were counted before and after applying the tools. After using tools carrots were handweeded and the time recorded. The carrots kept growing and we weighed and graded them at harvest. This trial was repeated 3 times in 2017.
SCIENTIFIC LANGUAGE – In a series of field experiments, we evaluated the impact of four in-row mechanical weeding tools on carrots (Daucus carrota) and two surrogate weed species: yellow mustard (Sinapis alba), and German millet (Setaria italic). Finger weeders (F), torsion weeders (T), flextine harrows (X), and Duo hilling discs (HD) were applied to carrots and weeds individually and in combination (tool ‘stacking’) when the carrots had 1 true leaf, approximately 25 days after planting. Tools combinations gave greater weed control and selectivity than single tools. The F+HD combination particularly, resulted in the greatest selectivity and reduction in the time required for subsequent hand weeding. No tool effects were detected on carrot quality or yield. However, across all tools, lower final carrot densities were associated with lower yields. The finger weeder controlled more weeds as soil moisture increased, or when more soil was moved into the carrot row. Whereas the torsion weeder did not appear to kill weeds through hilling and its efficacy was greater under relatively dry soil conditions. In many cases, yellow mustard was more susceptible to death by burial than German millet.
Eight different cultivars of carrots were grown and four types of in-row weeding tools (finger weeder, torsion weeder, Duo hilling discs, flextine harrow) were utilized to investigate carrot cultivar tolerance to mechanical weeding. We detected differences between cultivars in percent survival in 2 of 12 trials, once with the torsion weeder, and once with the flextine harrow. Differences between cultivars for full plant sizes and shoot sizes were observed at time of cultivation in only 1 of 3 field trials, but there were large differences in root size at the time of cultivation in every field trial. In two of three trials carrot survival in response to the finger weeder was related to both plant size, root size, and shoot size. A significant relationship was observed between cultivar seed size and plant size at the cotyledon and 1st true-leaf stage. Although highly significant differences in plant size, root, and shoot size exist between carrot cultivars at multiple growth-stages, these differences did not result in detected differences in carrot survival following in-row weeding tools.
Simple Conclusions – In-row weeding tools can be calibrated for young carrots to kill weeds and preserve the crop
The hilling discs and the Fingers+Hilling discs were the most selective (they were the best at killing weeds without killing carrots)
Duo+Fingers resulted in the least hand-weeding
None of the in-row tools caused forks, nicks, or disease in carrot roots
Detailed Conclusions – The Finger weeder + Hilling discs combination particularly, resulted in the greatest selectivity and reduction in the time required for subsequent hand weeding. No tool effects were detected on carrot quality or yield. However, across all tools, lower final carrot densities were associated with lower yields. The finger weeder controlled more weeds as soil moisture increased, or when more soil was moved into the carrot row. Whereas the torsion weeder did not appear to kill weeds through hilling and its efficacy was greater under relatively dry soil conditions. In many cases, yellow mustard was more susceptible to death by burial than German millet.
|Treatment||Trial A||Trial B||Trial C|
|Working depth (cm)||2.5-7.6||3.2||NA|
|Distance between hoes (between-row gap, cm)||10.1||14.0||NA|
|Approximate angle of tines into ground (degrees)||5.0||20.0||20.0|
|Working depth (cm)||6.4||3.8||5.0|
|Tine overlap (cm)||0.0||2.5||3.2|
|Down pressure (gap from arm to bracket, cm)||0.6||1.3||0.6|
|finger offset (yes or no)||no||no||no|
|Working depth (cm)||6.4||1.3||1.3|
|Finger distance – gap (cm)||3.2||3.2||1.3|
|Tine <, notches number from front||5.0||4.0||5.0|
|Working depth (cm)||6.6||3.8||3.2|
|Duo hilling discs|
|Distance between discs at bottom or top (width of cut, cm)||12.2||13.3||14.0|
|Distance between discs at front (cm)||15.6||20.3||19.8|
|Distance between discs at rear (cm)||11.9||12.7||8.9|
|Working depth (depth of cut, cm)||0.8-1.3||1.9||1.9|
|Carrots||Millet (weed)||Mustard (weed)||Average across trials A,B,C|
|Tool||Trial A1||Trial B||Trial C1||Trial A||Trial B||Trial C||Trial A||Trial B||Trial C||Carrot||sd||Millet||sd||Mustard||sd|
|Finger + Hilling discs||61||b||66||c||59||b||9||d||4||c||3||d||9||c||32||bc||42||d||62||4||5||1||28||9|
|Finger + Flextine||78||ab||69||bc||62||b||53||b||30||bc||22||cd||46||c||50||b||45||d||68||4||35||6||47||3|
|Torsion + Finger + Flextine||63||b||74||bc||70||ab||24||cd||26||bc||26||bcd||29||cd||46||b||59||cd||69||4||26||4||44||5|
Educational & Outreach Activities
The information gained from visiting European equipment manufacturers and farmers was shared with American growers by posting interviews from the trip on our youtube channel (MSU Mechanical Weed Control).
Posters describing this work were exhibited at grower and academic conferences (MOSES organic farming conference, Great Lakes Fruit and Vegetable Expo), and an academic conference in Switzerland for European weed scientists (2017 meeting of the EWRS Physical Weed Control Working Group).
Several articles sharing what we learned from this work were published in Vegetable Growers News Magazine.
Presentations on this work were given at several grower and academic conferences (MOSES organic farming conference, Great Lakes Fruit and Vegetable Expo, Bay Thumb Growers Meeting, Indiana Small Farms Conference, Wisconsin CSA Conference, Miller’s field day, 2017 meeting of the EWRS Physical Weed Control Working Group, Willamette Horticulture Society meeting).
The research was shared with over 130 farmers from all over the Midwest at the 2017 Midwest Mechanical Weed Control Field Day.
This research on using in-row tools was shared in three informational videos that are posted on our youtube channel (MSU Mechanical Weed Control).
In addition to our field trials, we introduced these in-row weeding tools and their use and possibilities to farmers all over the US through field days, print magazines, a podcast, and online videos. These in-row weeding tools, when properly used in a system designed for efficient mechanical weed control, can reduce the hand-weeding required on vegetable farms – and the many farmers who have begun to use these tools attest to their impact economically on their bottom line.
By trialing these in-row weeding tools intensively on a challenging crop we gained a better understanding of the possibilities and limits of each in-row tool. We also learned the importance of proper seedbed preparation and several other cultural techniques that contribute to the success of these tools. We tried several different methods of mounting these tools to existing American tool carriers, and learned a lot from these attempts.
“I had been removing weeds close to the row with my standard weeding tools, but always had to remove those weeds in row by hand. The MSU researchers brought a pair of finger weeders to my farm, and the clamps so that they would attach to my tractor. These finger weeders really were able to remove weeds in the row in many of my established crops, and I look forward to trying them in a lot of other applications.” – Mixed vegetable farmer from Michigan
“Even though we had the machinery, our mechanical weed control was poor, for years we had many interns to help with weeding by hand. But with changes to our farm recently we have much less labor. The MSU researchers lent us finger weeders and helped us set them up on our farm. They came by several times during the summer and gave us suggestions on how to use them – now we have used the least labor ever for weeding on our fall brassicas.” Educational farm in Michigan
Facebook was a great way to meet farmers interested in using these tools, to learn from them, and to share information through posting links to our youtube videos.
Growers really appreciated being able to borrow tools from us to see how they worked for them, instead of having to buy a machine sight unseen.
Thank you for allowing me to use some of the funds for the European research trip – I learned so much from speaking with farmers and tool manufacturers there, so that instead of trying to reinvent the wheel here, I could learn from their decades of experience with these in-row tools and apply that to our field experiments and share it with farmers.