In-Crop Weed Clipping for Organic Weed Control

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 Organic farmers need additional means of controlling in crop weeds, especially in poorly competitive crops such as lentil and flax. Cutting off immature weed seed heads and flowers above the crop canopy may reduce the viable weed seed bank resulting in cleaner, higher yielding crops. The Prairie Agricultural Machinery Institute in cooperation with the Marysburg Chapter of the Organic Crop Improvement Association recently completed a 3-year field trial examining the effectiveness of mechanical removal of above canopy weeds and the effect of removal on crop yield and subsequent weed population.

Clipping weeds above the canopy of a crop.

Weed clipping equipment
Three methods were assessed for effectiveness in clipping weed seeds above the crop canopy.
  1. Standard self-propelled (SP) swather with canvas removed.
  2. Modified self-propelled (SP) swather
  3. Prototype flail chain system developed by Crestview Organic Farms at Assiniboia

At a glance
Organic producers have serious annual weed problems. Wild mustard and wild oats are the predominant weeds especially in poorly competitive crops such as lentil and flax.

To reduce the number of weeds going to seed, PAMI modified a wide self-propelled swather to clip weeds above the crop canopy. In addition, PAMI tested a self-propelled swather modified with a series of flails to shred weeds above the crop canopy. The modified swather and swather/flail systems were very successful in removing more than 90% of immature weed seed heads and flowers above the crop canopy. Long term results include a reduced weed bank in the soil, cleaner crops, reduced weed dockage, and potential for improved crop yield.

SP swathers can be modified to effectively clip weeds above the canopy of poorly competitive crops, with removal of up to 90% of above canopy weed seed heads and flowers.

The effect of weed clipping on grain yield in the year of clipping was mixed, with higher yields from clipping at 2 of 4 sites. The effect of weed clipping on crop yield the year following clipping was mixed with higher yields for the clipped treatments at 2 of 4 sites.

Weed populations were dramatically reduced by weed clipping in 3 of 4 clipped sites in the year following clipping.

In conclusion, weed clipping can assist in reducing weed banks in soil and reducing weeds in the long term.

The swather and prototype flail chain system may also be an option in controlling weed population in organic crops.

A 42-page detailed report on organic weed clipping (Report #5199G) is available from PAMI. A shipping and handling charge will apply.

PAMI wishes to acknowledge the funding support provided by the Agriculture Development Fund (ADF) of the Saskatchewan Department of Agriculture, Food, and Rural Revitalization.

For the released report please open the PDF file in upper right corner.

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For more information about the content of this document, contact Darryl Slingerland.
This document is maintained by Nicole Huggins-Rawlins.
This information published to the web on October 26, 2004.
Last Reviewed/Revised on October 15, 2014.