Organic Agriculture

, Volume 5, Issue 4, pp 315–322 | Cite as

Improved herbicide efficacy for organically grown vegetables

  • John O’SullivanEmail author
  • Rene Van Acker
  • Robert Grohs
  • Rachel Riddle


Natural weed control alternatives that are currently approved for organic crop production are mostly nonselective essential oils used as postemergence, burn-down products. Their low efficacy requires multiple applications of high volumes to achieve good weed control. Natural herbicides approved for organic use lack systemic activity and have a nonspecific mode of action. There is, therefore, a need for new natural weed control products. This research evaluated improved biological and lower-risk herbicides that are appropriate for use by organic growers to provide enhanced weed management in organic crop production. These included manuka oil and Opportune. Natural triketones present in manuka oil have the same molecular target as some commercial synthetic herbicides. Opportune is a new organic bioherbicide based on thaxtomin, a phytotoxin derived from Streptomyces scabies. The objective of this research was to make available organically acceptable products from novel biological sources to control weeds in organic crop production by developing data on efficacy and crop safety for these products. The synergy associated with tank-mix applications of manuka oil with currently approved essential oils and acetic acid was demonstrated. Weed control with manuka oil, tank-mixed with Green Match EX, Weed Zap, or Weed Pharm was excellent, generally ranging from 90 to 95 % control. This synergy resulted in a 20 to 25 % improvement in overall weed control, compared to each product used alone. This is the key finding from this study and is of great importance to organic growers. This synergy has the potential to significantly improve weed management and will help growers to find solutions to the long standing issue of managing weeds in organic crop production. This research demonstrated novel uses for bioactive natural products to provide organic growers and the public with environmentally and economically sustainable alternatives to synthetic chemical herbicides. This represents an important step in fulfilling society’s desire for reduced dependence on synthetic chemical inputs. It will also serve as an important component for integrated weed management systems for organic agriculture. An integrated approach is the foundation of successful weed management. Improved weed management for organic crop production will help growers respond to the growing demand for organically produced food.


Manuka oil Thaxtomin Alternative weed control Synergy Soil activity Essential oils 



We thank Marrone Bio Innovations and Tairawhti Pharmaceuticals for Opportune and manuka oil research samples, respectively. This research was supported in part by financial support from Marrone Bio Innovations, Davis, CA, USA, Ontario Processing Vegetable Growers, London, Ontario, Agricultural Adaptation Council (Canadian Agricultural Adaptation Program), and the Ontario Ministry of Agriculture and Food and Ministry of Rural Affairs, Guelph, Ontario, Canada.

Conflict of interest

The authors declare that they have no conflict of interest.


  1. Dayan FE, Duke SO, Sauldubois A et al (2007) p-Hydroxyphenylpyruvate dioxygenase is a herbicidal target site for b-triketones from Leptospermum scoparium. Phytochemistry 68:2004–2014CrossRefPubMedGoogle Scholar
  2. Dayan FE, Cantrell CL, Duke SO (2009) Natural products in crop protection. Bioorg Med Chem 17:4022–4034CrossRefPubMedGoogle Scholar
  3. Dayan FE, Duke SO (2010) Natural products for weed management in organic farming in the USA. Outlook Pest Manag 21:156–160CrossRefGoogle Scholar
  4. Dayan FE, Howell JL, Marais JM et al (2011) Manuka oil, a natural herbicide with preemergence activity. Weed Sci 59:464–469CrossRefGoogle Scholar
  5. Douglas MH, Anderson R, Van Klink J et al (2001) Defining North Island manuka chemotype resources. Crop Food Res Rep 447:1–13Google Scholar
  6. Douglas MH, Van Klink J, Smallfield BM et al (2004) Essential oils from New Zealand manuka: triketone and other chemotypes of Leptospermum scoparium. Phytochemistry 65:1255–1264CrossRefPubMedGoogle Scholar
  7. Lee DL, Prisbylla MP, Cromartie TH et al (1997) The discovery and structural requirements of inhibitors of p-hydroxyphenylpyruvate dioxygenase. Weed Sci 45:601–609Google Scholar
  8. Owens DK, Dhammika Nanayakkara NP, Dayan FE (2013) In planta mechanism of action of leptospermone: Impact of its physico-chemical properties on uptake, translocation, and metabolism. J Chem Ecol 39:262–270CrossRefPubMedGoogle Scholar
  9. Norris SR, Barrette TR, DellaPenna D (1995) Genetic dissection of carotenoid synthesis in Arabidopsis defines plastoquinone as an essential component of phytoene desaturation. Plant Cell 7:2139–2149PubMedCentralCrossRefPubMedGoogle Scholar
  10. Stefanello MA, Pascoal ACRF, Salvador MJ (2011) Essential oils from neotropical Myrtaceae: chemical diversity and biological properties. Chem Biodivers 8:73–94CrossRefPubMedGoogle Scholar
  11. Young SL (2004) Natural product herbicides for control of natural vegetation along roadsides. Weed Technol 18:580–587CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2015

Authors and Affiliations

  • John O’Sullivan
    • 1
    Email author
  • Rene Van Acker
    • 2
  • Robert Grohs
    • 1
  • Rachel Riddle
    • 1
  1. 1.Department of Plant Agriculture, Simcoe Research StationUniversity of GuelphSimcoeCanada
  2. 2.Department of Plant Agriculture, Crop Science BuildingUniversity of GuelphGuelphCanada

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