Blackgrass in a Wheat crop

A weed can have many definitions, one being, any plant growing in a place it is not wanted.

Weeds can cause numerous problems to agriculture including:

  • Reductions in yield
    • Taking resources from the crop – nutrients, sunlight, and water
  • Impacts on crop quality
    • E.g. Charlock causing high euric acid in Oilseed rape
  • Harvest issues
    • Combining e.g. cleavers, bindweed
    • Root crops e.g. Fathen blocking harvester slats
  • Crop storage problems
    • Act as a host for pathogens and pests
  • Impact on livestock
    • Reduced feeding - thistles
    • Milk taint – wild garlic

Weeds can be controlled using many different methods, including:

  • Crop rotation
  • Cultivations
  • Hygiene
  • Hand removal (Rouging)
  • Increased crop competitiveness
  • Mechanical control
  • Chemical control

Weeds can persist in soil for many years. The scale of effect from the weed is influenced largely by the weed species, weed density and time of emergence relative to the crop. Understanding the biology of the weed species present is essential to identify weak points in its lifecycle and offer efficient control options, it is therefore key to identify weeds correctly.

Share any useful resources or tools for weed identification and management below.

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Integrated Pest Management highlights the growth of a healthy crop with the least possible disruption to agro-ecosystems and encourages natural pest control mechanisms. IPM is one of the tools for low-pesticide-input pest management, and IPM must now be implemented by all professional agchem users.

ADAS scientists help evidence and guide crop disease management by chemical, genetic and biological approaches. Our expertise covers all areas of disease management on the major crops. We lead multi-organisation collaborative research into disease management and preventation, as well as provide strategic consultancy.  

Brome grasses are becoming an increasing problem in arable cropping systems.

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Black-grass (Alopecurus myosuroides) is a major weed in winter sown cereals.

Herbicide resistance is the inherited ability of a weed to survive a rate of herbicide which would be lethal to a member of the normal population. It can develop over time based on repeated selection pressure imposed on the weed, this selection pressure changes the population from susceptible to resistant.  

This field lab was initiated as part of the ADAS project ‘Investigating the distribution and presence, and potential for herbicide resistance of UK brome species in arable farming’, funded by AHDB.  

App and website dedicated to pest, disease & weed identification and management.

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The Weed Resistance Action Group (WRAG) produces guidance on pesticide resistance issues. Hosted by AHDB, this information can be used to help protect crops and the long-term efficacy of herbicides.

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AHDB Publication 2018.

AHDB BBRO Review 2019 Research Review No. CP 182 / 1807258 - Review of weed control options

AHDB Report 636 from research project into Brome, reported September 2021 by Sarah Cook,

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