Biological Control of Weeds in turfgrass: opportunities and misconceptions

Abstract

Turfgrass systems may offer opportunities for overcoming some constraints on the successful implementation of weed biocontrol. Of the roughly 16.4 million ha of turfgrass in the USA, ≈60–75% are in residential lawns and 3% are golf turf. Annual expenditures for a standard herbicide treatment regimen for residential turf are estimated to be ≈US$326 ha−1, about 2–3‐fold greater than that for USA corn and soybean growers. Expenditures can be >US$3000 ha−1 for control of certain weeds such as Poa annua in high‐value areas including golf fairways or greens, but those applications are made to far smaller areas. Regulatory actions and consumer preferences are creating market opportunities for alternatives to synthetic herbicides in both commercial and consumer markets, but the size of these markets and willingness‐to‐pay are poorly documented. Turfgrass sites are intensively managed, yet despite the ability to modify site conditions through irrigation, mowing and fertility management, microbial biocontrol agents tested thus far have not provided the consistently high levels of weed control expected in the market. Recent advances in microbial bioherbicide products may offer a path to overcome many of the obstacles to success. No single herbicide will control the diversity of turfgrass weeds, nor will any single biocontrol agent or biopesticide. Successful development of weed biocontrol for turfgrass systems will require numerous, effective biocontrol agents for the many weed species found in turfgrass environments, as well as a deeper understanding of different turfgrass market segments, and weed management expectations for each segment. © 2023 The Author. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Why are there no widely successful microbial bioherbicides for weed management in crops?

“…A promising new mycoherbicide that is being commercialized for this situation is discussed below. Another potential situation in which a narrower host spectrum plant pathogen as a microbial bioherbicide could be useful is in places where people are willing to pay high amounts per unit area for weed management, such as golf courses and other high‐value turf settings 50 …”

“…Another potential situation in which a narrower host spectrum plant pathogen as a microbial bioherbicide could be useful is in places where people are willing to pay high amounts per unit area for weed management, such as golf courses and other high-value turf settings. 50 There are fungi that have a wide range of weed hosts (e.g. Fusarium oxysporum), but regulatory agencies must insure that a living microbial bioherbicide will not spread to non-target plants, including nearby crops and endangered species.…”

The future of microbial bioherbicides

“…The meeting was organized into twenty‐two 50‐min presentations with ample time for discussion. Sixteen of the articles in this issue are from conference participants 2–17 . Four related articles from non‐participants are also included 18–21 .…”

“…Sixteen of the articles in this issue are from conference participants. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Four related articles from non-participants are also included. [18][19][20][21] The article by Duke gives the rationale for the meeting, discussing the many microbial bioherbicides that have failed and detailing the technical and economic reasons for lack of success.…”

Implications of weakening of the United States Geological Survey Pesticide National Synthesis Project for Weed Scientists

“…Other habitats, such as rangelands, wetlands, and other natural and urban areas, are also affected by weedy and invasive plant species. Impacts of unwanted vegetation can include damage to infrastructure, damage to recreational space, altered water flow, degraded natural resources, reduced biodiversity and species displacement, and a loss of ecosystem services, among other effects (DiTomaso 2000; Jetter et al 2021; Neal 2023; Vilà et al 2011).…”