Ergot infection levels in the UK have reached unprecedented highs, leading to costly grain rejections and increased pressure on cleaning services. This fungal pathogen, caused by Claviceps purpurea, poses a significant human health risk due to the toxic alkaloids it produces. Whilst it doesn’t heavily impact crop yield, its presence severely affects a crop’s margin as grain merchants often adopt a zero-tolerance approach.
Why the surge in ergot?
The past year’s cool, wet spring, combined with a prolonged flowering period, created ideal conditions for increased sporulation and infection. Several evolving farm management practices are also contributing to the problem:
- Reduced ploughing: Historically, ploughing helped reduce ergot by burying infected fragments. However, the shift towards min- or no-till farming means these fragments remain on the surface.
- Increased secondary hosts: Environmental field margins and the proliferation of grassweeds increase the presence of secondary hosts for ergot.
- Constricted rotations: Limited break crop options are leading to repeated cereal crops, creating a continuous chain of infection.
- Open flowering varieties: Varieties with open flowering habits, common in many spring wheats, are more susceptible to infection.
Ergot isn’t just a seed-borne problem; it’s prevalent across the entire farm. The fungus infects open, unfertilised flowers of various grass hosts. Ergots then fall to the ground, remaining dormant until the following spring when they release airborne spores to infect new flowers. This leads to sticky “honeydew” that attracts insects, further spreading the spores. These ergots, which can be up to 2cm in length, are either harvested with the grain or fall back to the ground, serving as a source of inoculum for the next year.
The limitations of cleaning and legal limits
While colour sorting and cleaning technology can help, they add cost and don’t address the root cause of the infection. Furthermore, new EU regulations effective January 1, 2022, have reduced ergot sclerotia limits in unprocessed grain and established maximum levels for ergot alkaloids in processed cereal products. Even if grain meets the sclerotia limit, the processed product can still exceed the alkaloid limit, making on-farm management crucial. Removing sclerotia doesn’t always eliminate alkaloids entirely, as dust transfer, fragmentation of sclerotia, and the presence of alkaloids in “healthy” grain near infection sites can contribute to background levels.
On-farm management strategies
Experts emphasize a multi-faceted approach to tackling ergot at the farm level:
- Effective weed control: A year-round strategy targeting ryegrass and blackgrass is primary.
- Tillage practices: Deep tillage after harvest can bury ergots, but this must be followed by shallow tillage the following year to prevent them from returning to the surface. Ergots can remain viable for up to five years.
- Crop rotation: Avoid growing straw cereals for at least two years and adjust rotations accordingly. Consider moving to spring cropping to help control grassweeds.
- Seed treatment: While not eradicating ergot, some seed treatments like Rancona iMix can suppress the germination of ergot particles, potentially reducing incidence by 40-60%. Untreated farm-saved seed may contribute to the problem.
- Harvest management: Harvest ergot-infected areas of a field separately to avoid contaminating the bulk of the crop.
- Vigilance and planning: Be proactive. If you suspect an ergot problem, book seed cleaning services early, especially if you’re in a high-risk area or have a history of issues.
By implementing these strategies, growers can work towards mitigating the spread and impact of ergot on their farms.
Want to learn more?
Speak to the experts at Evans and Pearce to learn more about the growing threat of ergot, and how you can protect your crops.
