Organic Control of Perennial Weeds with Vinegar and Biologicals

Project Overview

Project Type: Farmer/Rancher
Funds awarded in 2011: $20,790.00
Projected End Date: 12/31/2012
Region: Western
State: Montana
Principal Investigator:
Jess Alger
Organic control of Perennial Weeds

Annual Reports


  • Agronomic: grass (misc. perennial), hay
  • Vegetables: lentils, peas (culinary)
  • Additional Plants: native plants
  • Animals: bovine


  • Animal Production: grazing management, pasture renovation, preventive practices, range improvement, feed/forage
  • Crop Production: cover crops, fallow, application rate management
  • Education and Training: demonstration, extension, farmer to farmer, networking, on-farm/ranch research
  • Farm Business Management: whole farm planning
  • Pest Management: biological control, botanical pesticides, chemical control, field monitoring/scouting, weed ecology
  • Production Systems: organic agriculture, transitioning to organic
  • Soil Management: green manures
  • Sustainable Communities: sustainability measures


    The purpose of this project was to determine effective, sustainable ways to control perennial, noxious weeds with biologicals and vinegar on organic farms and ranches. We found that vinegar was a very effective organic control for bindweed, Canada thistle, spotted knapweed and whitetop. We learned that 15% vinegar solution was strong enough to be effective, and that timing and treating especially first year growth increases treatment success. Re-treatment is also necessary for these persistent weeds; for best results, re-treating as often as four times in a growing season. Also, it is important to flush vinegar out of spray equipment to lengthen its life. Biological controls were effective treatments for leafy spurge and Canada thistle, though patience is required to see full benefit.


    Noxious weeds are persistent and hard to kill, even with the best technology. On organic farms and ranches, there has not been any good techniques demonstrated for effective long-term control of these types of plants. This project was developed to help determine what techniques might prove effective enough to be reasonable and sustainable so that a working organic farm or ranch might find them to be beneficial and economically justifiable.

    Project objectives:

    The objective of the project was for each of the producers to try new ways of treating their respective weeds of concern and find acceptable methods that would meet organic producer and economic targets.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.