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Risky Weeds in Risky Times

By Christine Gelley

Farming is truly risky business. Every moment of every day on the farm holds inherent risk. The main duties of the farm manager in any sector are to identify, evaluate, and mitigate risk. All the little steps of risk mitigation add up to make a big difference that we can’t always see, but can still save us time, money, and distress in the future.

One of the risks forage managers face on a regular basis is the threat of persistent weeds. Weeds are an issue that compound over time if not addressed soon after detection. Choosing to make the investment in weed prevention and control early can help prevent exponential population growth that is increasingly difficult to manage.

Any plant in the wrong place can be considered a weed, but not all weeds are created equal as threats in forage production. The more you know about weeds, forage, and soil health the more complex weed management and weed risk analysis becomes. All plants offer some benefit to an ecosystem, but we must weigh the benefits against the risks when we develop a weed management program in grazing and hay systems.

  1. Step one in your weed risk analysis process is to identify the weeds in your system. Forage crops are often a diverse mix of plants and it can be challenging to identify a plant as friend or foe. What seems like a weed to you may be a flower to your neighbor. In a forage system, weeds are plants that can cause health issues for livestock and/or out compete desirable plants for nutrients, sunlight, and square footage. Identifying the suspect weed by species is the only way to proceed to step two. To identify a weed, pay attention to plant traits including:
  • Site preference- soil moisture, terrain, sunlight?
  • Growth habit- climbing, upright, or creeping?
  • Woody or herbaceous- when traced back to the root, are the stems woody or soft?
  • Leaves, stems, and flowers- shape, size, color, hairs, thorns, secretions, scent?
  • Roots- depth, connected roots above or below ground, shape, and color?

         2.Step two is to evaluate the risk associated with the weed. Evaluate potential      threats including:

  • Toxicity to livestock- if so, at what levels, and what circumstances?
  • Allelopathy to surrounding plants- secretions that kill competitors.
  • Seed production- seed deposition leads to exponential growth.
  • Seed persistence- how long can seed stay viable in the soil?
  • Lifecycle- annual (summer or winter), perennial (cool or warm season), or biennial?
  • Rhizomes, stolons, and suckers- are there other methods of reproduction or regeneration, besides seed production?
  • Site preferences- soil fertility, texture, and moisture, sunlight, tilled or no-till?

         3.Step three is to mitigate the associated risk of the weed.

  • Consider why the weed is there and correct issues that may have led to establishment. These could include:
  • Fertility issues with the site that prohibit desirable plants from succeeding
  • Bare spots in the field from animal/machinery traffic or water flow
  • Introduction of seed by the wind, wildlife, machinery, or contaminated hay/seed/manure
  • Use an integrated pest management program to reduce the population. These strategies include a combination of:
  • Cultural control- strategic mowing, hand pulling, fertilizer application, tillage, and/or reseeding competitive beneficial plants
  • Biological control- strategic grazing if the weeds are edible, but still threatening
  • Chemical control- selective and safe use of approved herbicides to suppress weed growth and allow competing beneficial plants to regain ground
  • Evaluate the cost of each control method, both from the standpoint of production loss, upfront cost, and payback period. Financial analysis should answer these questions:
  • Can we afford this treatment (fertilizer, herbicide, new seeding)?
  • Can we afford to do nothing? How much estimated revenue has been lost from the weed competition and/or health complications of livestock?

Your local county ANR Educator can help you through a weed risk assessment and provide research-based consultation on mitigation techniques. Each forage system is unique and is best evaluated on a case by case basis. Please don’t hesitate to contact us for assistance even during COVID-19.

Some general advice when you are questioning a weed is: When in doubt, pull it out.

Wear gloves if you are concerned about potential skin reactions and collect as much of the specimen in question as possible. Photograph the weed from far away and close. Send the photos to your local extension service (or set up an appointment to meet if possible). Thoroughly describe the features listed in step one for the best chances of quick and accurate identification.

  • Don’t Forget!
  • Landowners of Noble, Guernsey, Muskingum, and Morgan County are still eligible to apply for cost recovery funds to treat spotted knapweed in pasture and hayfields. County Soil and Water Districts and OSU Extension are active partners in the program. The Spotted Knapweed Treatment for Ohio Producers (STOP) Project is funded through the Regional Conservation Partnership Program (RCPP), which is administered by the Natural Resources Conservation Service (NRCS).
  • While forage crops do not qualify for payment through the Coronavirus Food Assistance Program, cattle and sheep do. Eligible farmers from any state and any county in the U.S. can apply for CFAP through their local Farm Service Agency to receive a payment for commodity losses due to the pandemic. Perhaps consider using your CFAP payment as an investment toward things you’ve been delaying that will yield long-term benefits, like a fertility program, an improved livestock handling facility, better fence and water systems, winter feeding areas, or weed control.
Source : osu.edu