Using Nectar Cover Cropping in Vineyards for Sustainable Pest Management

Project Overview

Project Type: Research and Education
Funds awarded in 2007: $178,300.00
Projected End Date: 12/31/2010
Region: Western
State: California
Principal Investigator:
Mark Hoddle
University of California
Dr. Nic Irvin
University of California

Annual Reports


  • Fruits: grapes


  • Crop Production: cover crops, intercropping
  • Education and Training: demonstration, extension
  • Farm Business Management: budgets/cost and returns, feasibility study
  • Pest Management: chemical control, economic threshold, field monitoring/scouting, cultivation, row covers (for pests), trap crops, traps


    Research investigating the use of cover crops in southern California vineyards for pest control has demonstrated that access to floral resources greatly increases natural enemy fitness, and that cover crops may positively affect natural enemy numbers. However, additional irrigation required to keep cover crops alive over summer may lead to increased pest populations, reduced berry quality and increased vine vigor. Cover crops may harbor pathogens (Xylella) which could be transmitted to vines by sharpshooters. Summer cover cropping may not prove to be a viable option for grape growers in southern California due to cost of water and difficulty in establishing.

    Project objectives:

    1. Determine if buckwheat flowers and cahaba vetch extrafloral nectaries increase longevity and fecundity of key natural enemies.
    2. Determine when to sow cover crops to maximize nectar availability for natural enemies.
    3. Determine if buckwheat and cahaba vetch, sown in alternate rows of grapes, enhances natural enemy populations and reduces pest populations below economic thresholds at study sites over a two year period.
    4. Determine if buckwheat and cahaba vetch influence grape yield and quality.
    5. Determine if buckwheat and cahaba vetch affect vine vigor.
    6. Verify that buckwheat and cahaba vetch do not provide refuge for grape pathogens (e.g., Xylella) or pathogen vectors (e.g., sharpshooters).
    7. Determine if buckwheat and vetch out compete and suppress unwanted weed species.
    8. Determine the rate of dispersal of natural enemies from buckwheat and cahaba vetch plots.
    9. Extend the information gained from this research to the Californian grape community through outreach and education.
    10. Promote increased adoption of nectar cover cropping practices in Temecula, Lodi and Coachella Valley if research results merit application.
    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.