To uproot or bury weeds? Can simple models help us choose the right tool?

Research
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To Uproot or Bury Weeds? Can Simple Models Help Us Choose the Right Cultivation Tool?

Background: Deciding what tool or tool settings to use for in-row cultivation is not always obvious. If a crop is taller than a weed than tools that can precisely hill between those heights is likely a good choice for selective cultivation. Similarly, some growers will do a ‘tug’ test to see how well crops and weeds are anchored by their roots. If the crop has much greater “anchorage force” relative to nearby weeds, than tools that do some uprooting may be the best choice. Can such simple observations at different stages of crop-weed growth provide general insights into which type of tool and mode of action to apply? Can mathematical models based on these observations be used to identify general principles of tool selection and efficiently generate and test hypotheses to improve the chances of success?

Methods: To gain insight into these questions, MSU grad student Noelle Connors gathered data on carrot anchorage forces and heights relative to various weed species, and used that data to develop a model (based on Kurstjens et al. 2004) to predict which mode of action (hilling or burial) had the greatest potential for killing weeds without killing the crop at different growth stages. The model was also used to evaluate the relative impact of various cultural practices (which either increased the relative height or anchorage force of crops relative to weeds) on the efficacy of different physical weed control tools.

Results: Keeping in mind the many assumptions of the model, Noelle’s results suggest that for carrots, hilling generally has greater potential selectivity than uprooting, especially for grass weed species. The model also demonstrates and quantifies the potential benefits of cultural practices including stale seedbedding and use of high quality carrot seed for improving the success of mechanical cultivation.

For more details, see our recent poster from the WSSA Annual Meeting here:

2023 WSSA Connors Carrot Model.pdf (514.4 KB)

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You know it would be nice to see a comparison with just mowing as well… snipping the weeds off at a certain height. That seems to be a strategy for a few companies. Korechi and Greenfield are both selling mowers that work between the rows. It does not sound effective, but it’s fast and cheap. I always wonder about the production impact of just mowing to reduce weed pressure but not actually keeping the ground clean.

Mowers look like a good option for orchards at least - they are often mowed anyhow and it’s a chore. Mowers are maybe an option for maintaining/controlling living mulches.

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A nice piece of work. Good effort by Noelle and yourself. And if anyone is interested in a very simple and highly effective way to hill / bury weeds from tiny to large https://www.bhu.org.nz/future-farming-centre/information/bulletin/2018-v2/mini-ridgers-lethal-burial-depth-for-controlling-intrarow-weeds/ will explain how including the 1+2=3cm rule.