Field infested with Scentless mayweed, a common broadleaf weed

Broad-leaved weeds are a varied group of weeds that can grow and cause significant problems in arable fields in the UK.

Some of the most common broad-leaved weeds in the UK include: Common Chickweed (Stellaria media) , Scentless Mayweed (Tripleurospermum inodorum), Common poppy (Papaver rhoeas), Charlock (Sinapis arvensis L.), Fat-hen (Chenopodium album L.), Common groundsel (Senecio vulgaris), Docks (Rumex spp) and Creeping thistle (Cirsium arvense).

See also related topics of: grass-weeds, herbicides, herbicide resistance and integrated weed management.

Key features of broad-leaved weeds

  • Broad-leaved weeds are dicots meaning that each seed initially contains two embryonic leaves (cotyledons).
  • Often have wide, elongated oval leaves (nearly always wider than grasses) and branched stems.
  • Net-liked or branched appearance of leaf veins.
  • Many broad-leaved weeds (e.g poppy) have colourful flowers.
  • Seeds are often more persistent in soils than grass weeds.

Despite some key biological similarities, this a diverse group of plants with varying growth habits, ecologies and life-cycles (can be annuals, biennials, perennials). This can make management of broad-leaved weeds challenging.

 

Management Options

The main management options for broad-leaved weeds tends to fall into cultural and chemical (herbicide) control.

Cultural 

  • A wide range of cultural control techniques can be employed specific to the targeted weed. This may include using optimal rotations, tillage and cultivations, suitable crop row spacing, using competitive crop varieties/cultivars and altering key timings (e.g drilling dates). 
  • The aim is to have optimal field conditions that make it more challenging for weed population establishment and growth.

Chemical 

  • A wide range of pre-emergence and post-emergence herbicides can be used on broad-leaved weeds - most commonly this includes ALS inhibitors (e.g sulfonylureas) (HRAC Group 2) although resistance concerns with this group means alternatives are becoming in greater demand.
  • Unlike grass-weeds, broad-leaved weeds are generally naturally tolerant to ACCase enzymes (HRAC Group 1).
  • Common post-emergence herbicides include  HRAC Group 4 Auxin mimics (2,4-D and MCPA, dicamba, dichlorprop).
  • Common pre-emergence herbicides include: HRAC Group 3 inhibition of microtubule assembly (pendimethalin, dithiopyr, prodiamine), HRAC Group 9 inhibition of EPSP synthase (glyphosate)

 

Herbicide Resistance

  • Resistance to ALS inhibiting herbicides herbicides has been recorded in many UK broad-leaf weed populations
  • There has also been an incidence of resistance of Groundsel to triazinone herbicides (HRAC group 5 Photosystem II inhibitors)
  • This appears to be target site rather than enhanced metabolism (which is common in grass-weeds)
  • Glyphosate resistance risk should be continually monitored 

 

Please attach any relevant projects or pages linking to broad-leaved weeds to this topic page

Related Organisations

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Connected Content

Herbicide Resistance

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. Herbicide resistance is becoming an increasing problem in UK agriculture, in both grass weeds and broad-leaf weeds. See also the general topic on herbicides.

European Weed Research Society Workshop - Cambridge May 2023

'Integrated Weed Management (IWM) systems in the agroecology context; new challenges.' NIAB, Cambridge, UK 24th - 26th of May 2023

Cereals

Herbicides

Herbicides are substances (usually chemical) used to control weeds in a variety of situations including agriculture, horticulture and managed landscapes. Herbicides are classified according to their mode of action (MOA) - this is the precise biochemical mechanism in which the herbicide targets and kills the weed. The 'active ingredient' of the herbicide is the specific herbicidal compound that has the phytotoxic effect and this is formulated with a variety of other ingredients (including other active substances, surfactants, buffers, adjuvants e.t.c) to make a final product which is given a trade name by the herbicide manufacturer. With any herbicide product you will find an associated product label which explains how to use the product safely and legally. This page provides an overview of herbicides including how they are classified and used. Please link any pages or projects relating to herbicide use to this topic page.  Some widely used herbicides (e.g glyphosate) also have their own topic page. Other related topics on FarmPEP include herbicide resistance,  bioherbicides, broad leaved weeds and grass weeds.  

Grass Weeds

Grass weeds are a major challenge in UK agriculture and are often highly competitive in arable crops. Some of the most common grass weeds in the UK include: Black-grass (Alopecurus myosuroides), Italian rye-grass (Lolium multiflorum), Brome (Bromus sp.), wild-oats (Avena sp.), Couch grass (Elytrigia repens), annual meadow grass (Poa annua) and Rat's-tail Fescue (Vulpia myuros). You can find specific topic pages for black-grass and brome. See also related topics of: broad-leaved weeds, herbicides, herbicide resistance and integrated weed management

Glyphosate

The herbicide glyphosate was first registered in 1974 under the original trade name RoundUp (Monsanto) and has since become one of the most commonly used herbicides globally. It is a non-selective, post-emergent herbicide with a wide range of uses including arable, forestry, and horticulture.

Integrated Weed Management (IWM)

IWM involves using numerous weed control methods to try and manage a weed problem sustainably. Whilst herbicides can still be used as part of an IWM approach, a major aim is to reduce reliance on them by also incorporating methods including, cultural, mechanical, biological, thermal and genetic control. A combination of such approaches can allow for optimal control of a specific weed problem. Related topics on FarmPEP include herbicides and herbicide resistance. You can also view the topic pages on grass weeds and broad-leaved weeds which provide examples of suitable control methods.

Agricultural modelling for weed management

Crop modelling is a useful tool in agriculture to improve our understanding how a crop grows in interaction with all external factors, including environmental interactions and the crop management practices in place. The idea is that by modelling cropping system factors as a mathematical representation, and incorporating real past data to 'calibrate' the model,  you can then simulate various scenarios and predict the impacts of certain changes on crop growth. One example of this would be a simulation of predicted environmental conditions under various climate scenarios to predict the impacts of climate change on crop growth and yields. Whilst models are oversimplifications of reality and can never capture all the complexity of agricultural systems, modelling has been a vital tool underpinning key agricultural developments and models are constantly being developed to be more dynamic, complex and sensitive. One particular application of modelling is in weed control. This page highlights the application of modelling in weed management and introduces a case study of a weed model from a DEFRA report.       

The AHDB encyclopaedia of arable weeds

This guidance provides an easy reference to the major broad-leaved and grass weeds in the UK, including how to identify and manage them based on an understanding of their biology.

BCPC weeds knowledge bank

This site offers free access to Proceedings from over 50 years of BCPC Conferences and Symposia dating all the way back to 1954; over 100 Technical Reports from the Weed Research Organization; and the WRO Annual Reports which include reports from each research section of the WRO.

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