Sorting ergot issues in grain at harvest

Kristina Grenz discusses options to tackle ergot in contaminated grain at harvest.

In recent seasons, ergot has been particularly problematic.

The pathogen has capitalised on changes to farming systems that favour its life cycle, which include the greater use of reduced tillage and higher grass-weed pressures.

Last season, the weather ensured a winning combination, with cool and wet conditions during flowering encouraging infection and producing a record-breaking year for ergot.

Harvest 2025 looks better but the disease remains a threat.

Although ergot has negligible effects on yield, it produces toxic alkaloids that pose a health risk to humans and livestock when ingested, with pressure to drive down levels in the supply chain increasing.

Earlier this month, we released the results of a major review of ergot management guidance, which emphasised the need to combine interventions that target key stages in pathogen’s life cycle.

With harvest 2025 is underway, it is currently critical to reduce contamination risks:

• Identify and prioritise monitoring of higher-risk fields/areas (including grass margins)
• Harvest infected areas separately and segregate from other grain
• Check loads carefully before tipping onto a wider heap
• Clean contaminated grain

Although grain can be cleaned to various degrees, it is difficult to clean heavily infested grain sufficiently (it is also timely and costly).

The removal of ergot sclerotia can significantly reduce alkaloids in a grain sample, but it will not eliminate them.

Alkaloids, especially from broken ergots, can potentially transfer to ‘clean’ grain during processing, loading and transportation.

The relatively small and fragile ergot sclerotia from grass species are a particular pain.

This is why it is important to clean contaminated grain as early as possible to reduce sclerotia breakage, with grain destined for human consumption and farm-saved seed dealt with first.

To reduce ergot inoculum in your fields, it is important to drill high-quality, clean seed.

The UK Seed Marketing Regulations 2011 (No. 463) set the standards for ergot in for certified seed (visual inspection):

• Up to three pieces per 500 g (regulatory minimum standard)
• One piece per 1,000 g (higher voluntary standard)

These standards are not a legal requirement for farm-saved seed, but they provide a best-practice benchmark to help you manage inoculum build-up and spread.

• Only use seed from low-risk fields/areas for ergot
• Use representative grain samples to confirm ergot levels
• Do not sow badly contaminated seed
• Consider cleaning contaminated grain

There are several ways to remove ergot from grain, with colour or gravity separation the most effective.

In colour separation, grain is dropped down a chute, with digital cameras recognising defects (not just ergot) and compressed air deflecting unwanted material into a waste-collection area.

The cameras assess both size and colour, providing an efficient double-evaluation, with very little waste (as little as one tenth of gravity separators).

However, with high equipment costs and reduced flow-capacity during processing, it has slowed its uptake.

Modified gravity separation grades components in a grain sample by specific weight of products.

It can handle very slight differences in size and/or weight that cannot be separated by screening (width), aspiration (weight) or indented cylinders (length).

Aided by an airstream, ergot sclerotia (with lower specific gravity than the grain) are removed.

As ergot comes in many sizes and shapes, it is difficult to remove ergot sclerotia mechanically.

However, as grass-weed sclerotia are much smaller and thinner than cereal grains, it is possible to use a standard sieve cleaner to extract them (which sorts according to size and density), in some situations.

Sorted ergot

The black ergot sclerotia (in the bag) were removed from the grain using colour sorters operated by Camgrain (they have installed two recently, with each processing up to 35t/hour)