Ergot Control in Cereals & Grasses - April 2025

Ergot was particularly prevalent in the 2024 winter wheat harvest. How does ergot affect cereal crops (and grass-weeds), what is its impact on cereal yield and quality, and how can we better control it in 2025?

Key Points

• Ergot is a fungal pathogen which affects major cereal crops and various grasses.
• Ergot thrives in cool, wet conditions during the flowering period of its host.
• Wetter conditions as a result of climate change may increase the risk of ergot infection.
• Ergot infection has little direct effect on cereal crop yield, though it significantly affects grain quality.
• At present, there are no commercial cereal varieties with resistance to ergot, and there are no fungicides approved for use in cereals to control infection. The control of ergot currently relies heavily on non-chemical methods (e.g. cultural, rotational) via an Integrated Disease Management approach.

Background Information

Ergot is a fungal pathogen (Claviceps purpurea) which affects a range of major cereal crops, as well as various grass weeds (e.g. black-grass). Over the past three years, incidence of the pathogen has increased steeply¹. In order of decreasing susceptibility to infection in cereals, ergot affects rye, triticale, wheat, barley, and occasionally oats². The fungus thrives in cool, wet conditions during the flowering period of its host, which promote spore production and extend the flowering duration, thereby increasing the risk of infection. Late tillering crops and crops with secondary tillers are more susceptible. Ergot infection is characterised by the replacement of cereal grains with sclerotia (dark, elongated fungal structures), visible during the summer³. These sclerotia are distinct in appearance when infecting grassweeds, such as black-grass (Figure 1).

Figure 1. Ergot sclerotia on wheat (A) and black-grass (B). Sourced from AHDB (2024)³.

Disease Cycle

The disease cycle in wheat (Figure 2), as well as other susceptible cereals and grasses, begins when fungal sclerotia from previous infections overwinter in the soil. These sclerotia germinate in the spring or early summer under moist soil conditions, producing ascospores that are carried by wind to the host flowers. Under cool, wet conditions during flowering, these ascospores lead to infection by colonising the ovary, producing conidia spores. These conidia spores then mix with plant sap leaking from the site of the infection, forming so-called “honeydew”, which attracts pollinating insects that can further transmit the fungus and cause secondary infection in other unfertilised flowers. In addition, rain, and physical contact by humans, animals or equipment, can also spread the fungal spores and lead to infection at further sites. Following infection, sclerotia then develop in place of the cereal grain^2,4. Sclerotia that then later fall from the grain head typically survive in the soil for 1-3 years⁵, and can begin the disease cycle again having overwintered.

Figure 2. Ergot (C. purpurea) disease cycle in wheat. Sourced from Bayer Crop Science (2021)⁴.

Given that ergot infection favours wet conditions during flowering, climate change is expected to influence ergot prevalence moving forward. In recent years, the incidence of ergot and ergot mycotoxin contamination in wheat has increased, with a recent study linking greater incidence to increased weather variability and intensity worldwide, driven by climate change⁵. Extreme weather events, such as excessive rainfall, can create favourable conditions for the development of ergot and other fungal pathogens (e.g. increased humidity). As such, the risk of ergot infection in wheat and other cereals is likely to increase over time as climate change continues, posing a threat to food and feed safety, and human health⁵.

Impact on Cereal Yield & Quality

While ergot infection has little direct effect on cereal crop yield, it significantly affects grain quality. Sclerotia contain mycotoxins (toxic alkaloids), which are harmful to humans and animals if ingested, and can lead to a range of side effects including neurological (e.g. headache, psychosis, convulsion), alimentary (e.g. nausea, vomiting), and vascular (e.g. vasospasm – narrowing of the arteries)^3,7. As such, cereal grain contaminated with ergot necessitates thorough cleaning procedures to meet policy requirements and mycotoxin tolerance limits, which increases overall production costs and reduces its market value. In August 2024, the AHDB estimated the cost to clean ergot from wheat to be £10-18 per tonne of grain⁸.

Current Control Strategies

At present, there are no commercial cereal varieties with resistance to ergot, and there are no fungicides approved for use in cereals to control infection. As such, the control of ergot presently relies heavily on non-chemical methods via an Integrated Disease Management approach. Table 1 summarises key control strategies which should be used in combination to reduce the overall risk of ergot infection.

Table 1. Key control strategies for ergot. Information sourced from AHDB (2025)⁹ and Berraies et al. (2023)⁶.

Looking Forward – What are the Potential Options?

With the incidence of ergot infection increasing, the AHDB has recently commissioned an ADAS-led review (ongoing: Nov 2024-Sept 2025) to update the UK management guidelines for ergot. The review aims to improve overall understanding of the pathogen’s life cycle, and the ways in which risk can be more effectively managed in cereal crops. The review will also identify knowledge gaps and areas for future research focus¹⁰.

As described above, there are no commercial cereal varieties with resistance to ergot, and no fungicides approved for use in cereals to control infection. Although knowledge of the genes controlling ergot resistance in cereal crops is limited, recent genetic mapping research has made progress in identifying loci (specific location of a gene on a chromosome) for ergot resistance in wheat⁶. However, continued research and breeding efforts remain necessary to develop resistant commercial cultivars, while in the meantime, Integrated Disease Management approaches (Table 1) should be applied to minimise infection risk.

Concluding Remarks

The prevalence of ergot in the 2024 winter wheat harvest highlights the need for improved control measures to mitigate its impact on cereal grain quality and farm profit margins. Ergot thrives in cool, wet conditions, with extreme weather events such as excessive rainfall becoming more common due to climate change. While there are currently no commercial cereal varieties with resistance to ergot and no approved fungicides for its control, Integrated Disease Management via non-chemical methods such as crop rotation, grass weed control, and good crop husbandry, remain essential. Continued research and breeding efforts are necessary to develop resistant cultivars for commercial applications, and to enhance our understanding of the pathogen’s life cycle to better inform management approaches. The review commissioned by the AHDB to update the UK management guidelines for ergot will conclude in September 2025¹⁰.

References

1. Farmers Weekly (2025) Why ergot contamination of grain is higher than expected

2. AHDB (2025) An introduction to ergot and its management in cereals

3. AHDB (2024) Ergot in harvest 2024 cereals: A pathologist’s paradise (a supply-chain challenge)

4. Bayer Crop Science (2021) Managing ergot in cereal crops

5. Peloso et al. (2024) Climate effects on ergot and ergot alkaloids occurrence in Italian wheat

6. Berraies et al. (2023) Ergot of cereals: Toxins, pathogens and management

7. Garcia et al. (2000) Chronic ergot toxicity: A rare cause of lower extremity ischemia

8. AHDB (2024) How costly is ergot on milling wheat? Grain market daily

9. AHDB (2025) Management of ergot in cereal crops

10. AHDB (2024) Updating UK management guidelines for ergot (a review)