Weed research for cereals and oilseeds

An over-reliance on a limited group of herbicide modes of action has accelerated the development of resistant weeds. Our research helps to identify resistance risks and improve management guidance for the control of grass weeds and broad-leaved weeds.

The loss of key herbicide active ingredients in cereals and oilseed rape due to changes in legislation has been compounded by resistance to many of the remaining herbicides. Controlling herbicide-resistant weed populations incurs additional costs.

In particular, a dominance of autumn-sown arable crops and herbicide resistance mean black-grass has become a major headache for many farmers. However, populations of wild-oats, rye-grass, poppy, chickweed and mayweed have all been found to be resistant to some herbicides in some locations. Resistance issues are also emerging in bromes. In 2025, populations of Italian rye-grass were also confirmed to be resistant to glyphosate at the maximum label rate. 

AHDB research focuses on:

• Monitoring herbicide resistance presence and distribution
• Exploring integrated pest management (IPM) options for control
• Communicating weed management guidance

Weed Resistance Action Group (WRAG)

AHDB works with WRAG to develop, produce, and promote guidance on herbicide resistance.

The 2022/23 review of the Recommended Lists for cereals and oilseeds (RL) identified an appetite for crop physiology information to assist with variety selection under lower inputs, including variety competitiveness against grass weeds. There is already good evidence that crop selection influences weed control (e.g. barley is more competitive against black-grass than wheat). However, the use of competitive varieties is poorly understood.

In 2017, the Organic Research Centre developed a network to evaluate field-scale winter wheat variety trials on commercial farms, which identified the main traits associated with weed competitiveness. In 2025, AHDB funded an extension of the network to focus on low-input systems. The project will develop recommendations for measurable crop physiology traits and ultimately give farmers better information on the weed competitiveness of varieties.

In 2021, WRAG glyphosate guidance was updated. It included a revision to dose to ensure that there are ‘no survivors’ following an application. Survivors help drive the evolution of herbicide resistance. Typically, annual grasses require a minimum of 540 g a.i./ha for seedlings up to 2–3 leaves, 720 g a.i./ha when tillering and 1,080 g a.i./ha when flowering. The specific tillering dose was new. Robust rates are needed to ensure complete kill. The revised guidance was based on the results from a five-year investment in research by AHDB. In 2025, WRAG confirmed the first cases of resistance to glyphosate in a UK weed species (Italian rye-grass).

Information on all pest research projects is available in our research archive:

• In the ‘Sector’ drop-down box, select ‘Cereals & Oilseeds’
• In the ‘Topic’ drop-down box, select ‘Weed management’

Note: A report is submitted at the end of each project. After review (which can take several weeks), the final project report is published on the corresponding project page. At this stage, the project is official complete.