Integrated Weed Management

The use of a range of methods, applying the standard hierarchical model of cultural (sometimes referred to as ecological control), physical/mechanical, biological, and finally chemical approaches to the control of weed growth.

Often there will be a combination of control methods to help keep weed growth and coverage to within a desirable threshold. At certain times of the year weed growth can be very prolific and this can often require additional efforts or a change of method to control the often rapid and expansive growth. Integrated weed management is often shortened to the acronym IWM.

Some equipment may only be suitable for certain types of surfaces, for example, mechanical control of weeds using metal bristles on rotary brushes are not suitable for routine maintenance of turfgrass surfaces because the action of the bristles and the rotating action of the machine will tear apart the grass sward. However, metal tines or blades on specialist turf care machinery such as scarifiers or verticutters are ideally suited to the control of turfgrass weeds.

The focus of the following comments is on a turfgrass surface.

The first hierarchical stage of integrated weed management is that of cultural control. This involves creating a sward that is hard wearing, maintains good density so as to reduce the area available for weed colonisation, and is resilient being able to rapidly recover from wear and stress thereby making the sward more competitive against potential weed invasion. So, good aeration, fertiliser and irrigation practices, as well as correct mowing regimes, will all contribute to producing a sward that provides the foundation for a defence against weed invasion.

Next up is physical control, which will typically be regular hand weeding to try and keep wees down, as well as to remove young weeds once they are noticed, especially in fine turf situations. Where weeds are present in surrounding hard surface areas, then the use of thermal controls might be considered, for example, (1) burning by flame typically using propane gas as the fuel source, (2) steam from hot water to effectively dry out and melt the plant surface layers, (3) hot water sprayed onto weeds, (4) hot foam which smothers the weed and also dries out and melts the weed, as well as (5) battery electric control through high voltage contact with a weed which heats up the water within a plant therefore causing it to die. All these five thermal methods are non-selective so cannot be used as part of routine turf maintenance practices.

Mechanical control is through the use of machinery to control weeds and this will often from the main part of routine turf maintenance practices. So, as mentioned before the use of scarifiers, verticutters and mowers in particular to physically impact on weeds that are present.

Biological control of weeds might involve the use of insects or plant pathogens to control weeds, as well as animals to graze grassland. However, for turfgrass situations, these are not practical methods as of 2026. One biopesticide is Barrier H, with the active ingredient being citronella oil (23% v/v), that can be used on amenity turf (although the authorisation for use is planned to end on 28th February 2027) to control ragwort, so would primarily be for grasslands on which animals graze.

Chemical control, through selective herbicide use, would typically be the final choice for IWM. Setting an acceptable maximum level, or threshold, of weed content within a turfgrass area is an important first step in the process of IWM.

A useful guide to helping determine what might be a suitable threshold is through the use of performance standards. These provide pre-set values, which can be adjusted to suit local needs, for different quality levels for sports pitches, as well as for amenity grass areas.