Sheep vs. Weeds: Biological Control Agents to Combat Noxious Weeds

Project Overview

Project Type: Farmer/Rancher
Funds awarded in 2005: $4,570.00
Projected End Date: 12/31/2007
Region: Western
State: Oregon
Principal Investigator:
Cameron Gillespie
Gillespie Grazing Co.
Sabrina Gillespie
Gillespie Grazing Co.

Annual Reports


  • Agronomic: wheat
  • Animals: sheep


  • Crop Production: organic fertilizers
  • Education and Training: display, extension, focus group
  • Farm Business Management: budgets/cost and returns
  • Pest Management: biological control, integrated pest management, prevention, weed ecology

    Proposal summary:

    In Umatilla County, Ore., as farmers increasingly reduce the tillage on their cropland, weeds like kochia, prickly lettuce, Canada thistle, Scotch thistle and yellow starthistle have flourished. To counter the invasions, farmers are spraying more herbicides. As a biological alternative to these herbicides, the Gillespie Grazing Co. will use its Western SARE Farmer/Rancher grant to test an integrated pest management strategy using sheep to suppress the weeds. Cameron and Sabrina Gillespie will use solar-powered electric fencing and guard dogs to manage the grazing of their 800 ewes on untilled fallow. Their experimental design will encompass three plots – grazed, not grazed and control. During the season, they’ll evaluate weed numbers on each and sample for manure, soil compaction and soil moisture. They hope this large-scale weed control demonstration will demonstrate the value of sheep as bio-control agents on cropland weeds.

    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.