Managing weed seed rain: A new paradigm for organic and low-input farmers

Project Overview

Project Type: Research and Education
Funds awarded in 2006: $156,520.00
Projected End Date: 12/31/2010
Region: Northeast
State: Maine
Project Leader:
Dr. Eric Gallandt
University of Maine

Annual Reports


  • Agronomic: corn, soybeans
  • Animal Products: dairy


  • Crop Production: conservation tillage
  • Education and Training: demonstration, extension, farmer to farmer, on-farm/ranch research, participatory research
  • Farm Business Management: budgets/cost and returns
  • Pest Management: biological control, competition, cultural control, physical control, prevention, weed ecology
  • Production Systems: agroecosystems
  • Soil Management: green manures

    Proposal abstract:

    Modern weed management strategies continue to be focused on controlling weed seedlings, most often using herbicides or cultivation. This focus on early season weed control effectively minimizes yield loss due to weeds, but weed seed rain from individuals that survive may be extraordinary, resulting in a recurring weed problem. Furthermore, growers are frequently encouraged to plant fall cover crops, an operation that usually involves tillage and, consequently, burial of the new seed rain. Burial effectively places the weed seed in “cold storage,” offering protection from predators, and fewer environmental cues to encourage germination, a fatal process when it occurs late in the year.

    The proposed project will use our current knowledge of weed seedbank ecology to evaluate the efficacy and economics of fall weed management tactics designed to maximize weed seed mortality. Specifically, we will engage ten Maine farmers in related on-farm trials focused on fall weed management strategies including: preemption of seed rain by hand hoeing/pulling, tillage, or mowing followed by fall cover cropping; managing seed rain by flail mowing for maximal presentation to post-dispersal seed predators (exclosures will demonstrate the contribution of various weed seed predator guilds); and no-till seeding of fall cover crops to maintain weed seed on the soil surface where they are exposed to weed seed predators. A replicated comparison of these treatments will be conducted at the University of Maine Rogers Farm. Case studies detailing the on-farm fall weed management trials will demonstrate to farmers throughout the region the longer-term benefits of weed control strategies that focus on the seedbank instead of solely on early season competition.

    Performance targets from proposal:

    Through field days, meeting presentations, and published case studies, 150 New England vegetable and organic dairy farmers will learn about the Fall Weed Management Project; direct-mail and follow up telephone surveys will demonstrate that one third of this target audience implemented a new strategy focused on fall weed management, with 10% of the group adopting multiple tactics to preempt seed rain and maximize weed seed predation and mortality.

    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.