Grown in Marin
University of California
Grown in Marin

Alternative Weed Management - 12/14/17

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Star Route Farms and University of San Francisco hosted a group of 30 producers from around the region to dig into the art and science of weed management in row crop systems.  UC Weed Specialist, Steve Fennimore came from Salinas to talk through the life cycles of weeds, their strengths and weaknesses, and the importance of a relentless program aimed at reducing the seed bank in field soils.

Among the strategies discussed for reducing the seed bank were:


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  • Manage amendments like manure and compost to ensure temperatures get high enough to kill weed seed
  • Avoid bringing new seeds into fields on boots, tractors and tools
  • Do not allow weeds to go to seed

Prior to planting:

  • Preparation of stale beds including pre-irrigation to germinate weed seed
  • Pre-plant destruction of newly germinated weeds through
    • Flaming
    • Shallow Tillage
    • Solarization
    • Steam (still in experimental phase)
  • Establishing mulches with plastics or cover crop debris and other organic plant material


  • Flaming prior to crop emergence – particularly slow germinating direct-sown crops like carrots
  • Mechanical cultivation, including in-row weeding tools like the finger-weeders shown in this video from Cooperative Extension, Monterey County

Following Steve Fennimore’s presentation, there were field demonstrations of tractor and ATV-mounted flaming rigs from Star Route Farms and Gospel Flat Farm as well as a multi-purpose cultivation rig built by Gospel Flat’s Mickey Murch.

Interpretation during both the presentation and field demo was provided for Spanish-speaking crew and equipment operators.

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Send follow-up questions to: Steve Fennimore at the US Ag Research Station in Salinas at: or 831-755-2896

Additional resources mentioned in discussion during the workshop:


- UCANR solarization resources

- Cooperative Extension, Monterey County mechanical cultivation resources

Stevan Knezevic, Professor of Integrated Weed Management at University of

Eric Gallandt, Professor of Weed Ecology at University of Maine

- R.J. Stephen’s Theory and Practice of Weed Control

- UCANR Weed Management resources (in lettuce)

- University of Vermont summary of mechanical cultivation tools and weed control pros, cons, and sources

- SARE’s classic cultivation guide, “Steel in the Field”

Proceedings from European Weed Research Society meetings on “Physical & Cultural Weed Control” – (research by Pieter Bleeker frequently cited)

- Local source for mechanical cultivation tools & parts, Hilleby, Intl. Inc.
(in Woodland, CA)


- Weed Management presentation by Steve Fennimore

- "Organic Weed Management", 
Steve Fennimore

- "Weed Seed Biology", Steve Fennimore

- "Practical Weed Control", P. Bleeker

- "Opportunities for Biological Weed Control in Europe", P.C. Scheepens, et al.

- "Innovative Weed Control – Further Information", Charles Merfield, Certified Organic Association of BC

- "Weed Management on Organic Farms",
D. Finny & N. Creamer, NCSU CEFS


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