Cereal disease management: Your ergot questions answered

Kristina Grenz provides answers to some frequently asked questions (FAQs) about ergot management in cereals.

During my first year as AHDB’s Senior Cereal Product Quality Scientist, I’ve spoken with many farmers at events and discovered a strong, collective appetite to tackle ergot.

Although ergot has negligible effects on yield, it produces toxic alkaloids that pose a health risk to humans and livestock when ingested.

With increasing pressure to drive down levels in the supply chain, it has piqued interest in the disease and generated many questions about ergot management.

There was not a definitive source of answers until we published a comprehensive review of ergot management guidance in July.

The review pulled apart the various components of ergot management and provided answers to key questions, which include those cited below.

How far do ergot spores spread?

Ergots in the soil or on crop debris (ergots may also be in drilled seed) become active in the spring and summer, eventually releasing primary spores (ascospores).

These are carried in the wind, in the hope of landing on open flowers of cereals and grasses, leading to the infection of ovaries. Infected ovaries also produce secondary spores (conidia) that contribute to disease spread.

The good news is that ergot spores do not spread far from the source. In fact, a study in France saw a 50% reduction in disease level within 5 m of the primary source of ergot and a 95% decrease in ascospores spread within a 20 m radius of the source.

Do flower margins increase ergot risk?

Not all flowers are suitable hosts for the pathogen. Ergot specifically infects cereal crops and some grass species. If your margins include grasses, they may become a source of secondary spores and facilitate the spread of ergot.

Table 3.3 in the ergot review (on page 14) – see the PDF at the bottom of this web page – provides a detailed overview of the ergot risk associated with various grass species found in margin seed mixtures.

It also provides information on flowering times. If possible, avoid late-flowering grass species. Additionally, mow grasses regularly, if allowed.

Which varieties are most susceptible to ergot?

Compared with some of the potentially yield-reducing foliar diseases, breeding for ergot avoidance or resistance has not been a key target for plant breeders.

However, selecting varieties that have a short flowering period, more closed flowering habit, and high pollen shedding ability could help contribute to a reduction in ergot infection. Unfortunately, information on these traits is not readily available.

Avoiding varieties that are prone to producing many late tillers can help reduce the length of the flowering period within a crop and reduce infection risk. However, evidence on the impact on ergot levels is currently anecdotal.

There is tremendous potential to improve understanding of how variety choice contributes to ergot management. We are exploring if and how we can incorporate information on ergot into the Recommended Lists (RL), but it is early days and there is a long road ahead.

What effect does copper have on ergot?

In wheat and barley, copper deficiency can cause pollen sterility, which promotes more open flowering. This provides better access for spores to land on the stigma hairs, where they germinate and grow down into the ovary.

However, copper deficiency is not widespread in UK crops. It has only been recorded in a few soil types in the UK, specifically cereals on sands, peats, reclaimed heathland and shallow soils over chalk.

On land at risk from deficiency, it is important to monitor crops and to consider the use of soil or foliar applications of copper to help correct any deficiency identified, which may also help reduce ergot levels.

How is ergot best managed?

Based on the review, we published four management strategies that tackle specific points in the ergot life cycle to reduce ergot levels.

In line with integrated pest management (IPM), the key to success is to layer multiple strategies.