Understanding Ergot Outbreaks and How to Manage Them

October 20, 2025

Some farms in Southern and Central Alberta experienced ergot outbreaks this year. The infection produces ergot bodies, which causes yield reduction, grain downgrading, and mycotoxin (alkaloids) contamination. In addition, infected grain needs to be cleaned to remove the ergot bodies before using as seed or livestock feed. Ergot bodies from previous years also increase the risk of ergot outbreaks in following years.

This article will dive into the reasons for the outbreak, management measures and considerations for the following year.

Which crops are affected by ergot?

Ergot can occur on cereal crops, including from least to most affected: oat, barley, wheat, durum, triticale and rye. In addition, tame and wild grasses are also hosts of ergot.

Figure 1. Ergot bodies on hosts commonly seen in the Prairies. a. wheat; b. rye; c. grass. Photo credit: Michael Harding.

What are the risk factors causing ergot outbreaks?

1. Presence of ergot spores due to sclerotia at or near the soil surface.

2. Cereal crops with open flowers as a result of crop type or soil copper/boron deficiencies.

3. Conducive weather for fruiting body development, spore production, spore germination and infection (precipitation or high humidity).

4. Insects vectoring ergot spores from grasses to cereal crops via ‘honeydew’.

Hard purple-black bodies called sclerotia survive the winter in soil. Soil moisture favours germination of sclerotia to produce the small “drumstick-like” fruiting structures and the ascospores within them. Once the ascospores land on the heads, moisture facilitates ascospore germination and the infection of cereal head. Cereal crops are most susceptible to ergot during flowering. A main driving factor is the weather before head emergence and shortly after head emergence when crops are flowering. Rainfall and/or high humidity during this window promotes the sclerotial germination, production and release of spores and is necessary for spore germination and infection.

Following initial infection of cereal ovary tissues, the ergot pathogen produces the “honey-dew” stage which is comprised of masses of conidia that are dispersed by rain droplets and are attractive to insects. These insects can spread the conidia (spores) to adjacent cereal heads leading to more infections. Eventually, cereal ovary tissues infected by ergot pathogen differentiates into hard blackish-purple sclerotial bodies, which are produced instead of seed.

Often in outbreak years, ergot gets started early in wild and tame grasses around field margins, especially when abundant rainfall drives growth of the grasses. The disease can then easily spread via splashing or insect activity into nearby cereal crops that flower later.

Besides the field in question, one should also look at whether adjacent fields have wild or tame grassy areas and field margins, in the current or previous years. Grasses are also hosts and can serve as an important reservoir of ergot. They can be a source of ergot bodies and ascospores that infect adjacent cereal crops. Note sometimes the headlands of a field may be more affected by ergot as these areas are immediately adjacent to grassy areas which can act as sources of inoculum.

Figure 2. a. Honeydew stage of ergot; b. ergot with drumstick structure; c. ergot body on cereal head. Photo credit: a&b- Dr. James Menzie; c - Dr. Kelly Turkington.

Figure 3. Disease cycle of ergot of small grain cereals and grasses. Source: https://www.apsnet.org/edcenter/pdlessons/Pages/Ergot.aspx

Additional risk factors related to the ergot outbreak this year?

Since cereal crops are susceptible during flowering, any factor that lengthens this susceptible window will increase the risk of ergot.

Additional risk factors are secondary tiller development and pollen viability. A few reasons contribute to secondary tiller development. One of them is lower seeding rates that pushes plants to compensate through tillering. The other is variable crop emergence due to dry spring soil moisture conditions. In some cases, spring drought followed by moisture later in the season may lead to variable crop stages and more secondary tiller development. Secondary tillers and more variable crop development result in a longer window for ergot infection compared to more uniform crop development.

Figure 4. Late tillers due to dry spring and mid-season rain. This may increase risks for ergot outbreak. Photo credit: Jeremy Boychyn.

Other factors, such as heat/drought stress and shading can create pollen viability issues, leading to greater cereal floret opening and thus more exposure to ergot ascospores.

Copper and or boron deficiency can also lead to pollen sterility/viability issues, making the wheat/durum or barley florets to open to a greater extent, thus exposing the ovary and associated tissues to greater risks of infection by ergot ascospores.

Figure 5. Risk factors contributing to ergot outbreaks.

Are ergot outbreaks variety-related? Are certain crops/varieties more susceptible?

Crop species have an impact on ergot severity. Rye and triticale are considered the most susceptible among the cereal crops, followed by durum, wheat, barley and oats. The susceptibility of rye and triticale is due to their being cross-pollinated crop species with more open florets versus wheat and barley, which are mainly self-pollinated and have more closed florets (Menzies and Turkington, 2015).

However, within the same crop species, ergot infections are unlikely to be variety related. Research by Dr. Jim Menzie found little consistency in terms of variety effects. There may be subtle differences, but this may be more related to their flowering habits, and whether head emergence coincides with favourable weather and inoculum conditions for infection.

Currently, there are no consistent ergot resistance ratings established for western Canadian cereal varieties.

Can ergot-infected grains be used as seeds?

In general, yes, but actions are required to lower the risks.

Cleaning seed lots with ergot can help with grade but also improve quality of the seed.

Fungicidal seed treatments can help by limiting ergot sclerotia germination.

Planting the seeds >=2 inches in depth also lowers the risks of ergot. Ergot sclerotia need to be at or within 1/2 an inch or so of the soil surface to release spores that may cause in-season outbreaks. This allows the stalk of the ergot drumstick to reach the soil surface. If ergot sclerotia are planted with the seed, they typically are placed too deep. The risk of the “drumstick” stalks reaching the soil surface and releasing spores is limited.

Can grain cleaners remove the ergot in grains?

Grain cleaners/sorters can be quite effective at cleaning ergot-contaminated grains. They can open up marketing options by improving grade, addressing concerns related to alkaloid contamination of grain and the use of ergot-contaminated grain for seed.

Gravity tables and spiral cleaners are reasonably effective. Colour sorters are newer technology and are considered to be more effective, but cleaning costs and processing times may be increased. It is recommended to contact your local seed cleaning plant to discuss cleaning options and costs.

In some cases, certain parts of the field, such as headlands or low-lying areas, are more affected by ergot. One can harvest and store the grain from these areas separately from the rest of the field. UK research also indicates that plants along tramlines may produce more secondary tillers, which can increase the risk of infection. This may be a consideration for irrigated production where you have wheel tracks.

Does it bring higher risks to a field that had ergot outbreak? What are the crop rotation considerations?

Yes. Fields that experienced ergot outbreak this year could become a source of inoculum for next year. The risks are higher in the same field, as well as in the adjacent fields.

A field that had an ergot outbreak should be rotated out of host crop for at least TWO years. Originally it was thought that a single year of a non-host would be sufficient. However, research and past experience suggests that with the common cereal/canola/cereal/canola rotations on the Canadian Prairies, a single year of a non-host crop is not sufficient for the natural destruction of ergot bodies. Growers are recommended to rotate the field out of host crops for MORE THAN one year. Triticale and rye have the highest risks and should be especially avoided in subsequent years.

How to manage ergot going forward?

As you might be aware, diseases occur when all three factors in disease triangle are met: susceptible host, presence of pathogen, and favorable environment. To manage ergot, one can look at minimizing risks from each of the three factors.

Minimize inoculum

Use non-host rotation crops (e.g. pulses or oilseeds) for at least two years between cereals.
Mow ditches, roadsides and headlands before seed set to reduce early season ergot infections and “honey-dew” spores in grasses and to reduce ergot body populations in subsequent years.
Control grassy weeds and volunteer cereals.
Bury infested crop residue 2 inches or more to prevent ergot bodies from releasing spores.
- This may not eliminate the risk as subsequent tillage operations may bring the ergot sclerotia back to the soil surface.
- Avoid relying on tillage to manage ergot. Ergot outbreaks still occurred when conventional tillage was widely used. Keep in mind that excessive tillage can compromise soil quality and health and increase the risks of soil erosion.
Avoid planting seed containing ergot bodies.
Clean grains to remove ergot bodies.
Use seed treatment to reduce the viability of sclerotia.
Timely fungicide application.
- Recently ergot has been added to the labels on newer generation fungicides and applications around heading and anthesis may suppress infections due to ergot.
- However, past research from the UK suggests fungicides may not provide sufficient levels of control given fungicide active movement to ovary tissues is limited.
- Similar to the use of fungicides for fusarium head blight suppression, timing for ergot is critical and applications need to directly target head tissues, especially around anthesis, while variable crop development and head emergence may compromise suppression.

Host

Ensure adequate copper and boron availability to avoid excessive flower opening caused by pollen sterility, especially in more self-pollinated crops such as wheat and barley. Test soils for copper and boron and apply the right amount if supplementation is needed.
Recognize the elevated risk associated with cross-pollinated crops such rye and triticale.
Try to avoid low seeding rates, while minimizing stand establishment issues that may affect the crop at seeding and seedling emergence.
Options for genetic resistance to ergot are currently limited. Although ongoing breeding efforts in cereals are looking at reducing the susceptibility of host plants, favorable weather conditions and high levels of inoculum may still result in ergot issues.

Environmental conditions, in dryland crop production, cannot be managed through agronomic practices. However, one can monitor the weather during flowering and take actions if the conditions are favorable and the risks are predicted to be high.

Irrigation management might be a potential option to consider. Limiting irrigation just prior to head emergence and soon after head emergence may help to lower sclerotial germination and ascospore production and subsequent host infection, respectively. Similar approaches have been used to reduce the risk of Fusarium head blight.

Ultimately, one may still have ergot development, and thus harvest strategies should be used including:

Harvest management

Harvest and bin headlands separately because they will likely contain most of the ergot bodies.
Delay swathing to allow wind to dislodge ergot bodies from infected heads. Please consider the risks of shatter or pre-harvest sprouting associated with this decision.

Takeaways

The main drivers of ergot infection are: 1) presence of ergot spores, 2) open flowers on cereal or grass hosts, 3) and rain events/humidity before head emergence and during flowering

To reduce the risks ergot:

Rotate away from cereal crops for fields that had previous ergot outbreaks.
Ensure adequate copper and boron fertility to prevent excessive opening of cereal florets.
Minimize tillering and shorten the flowering window by increasing seeding rates.
Mowing of tame and wild grass around cereal fields before grasses flower can prevent ergot moving in from the field margins.
Grain cleaning can improve the grade of the grains and reduce mycotoxin (alkaloid) contamination levels. It also reduces the risk of introducing ergot bodies if the grain is used as seeds.

Ergot outbreaks are not likely to be variety-related, although rye and triticale do tend to be more susceptible than other cereal crops.

Similar to Fusarium head blight management, an integrated approach is needed for successful ergot suppression.

Resources

Ergot of Cereals and Grasses – Alberta Agriculture and Irrigation

Menzies, J. G. (2004). The reactions of Canadian spring wheat genotypes to inoculation with Claviceps purpurea, the causal agent of ergot. Canadian Journal of Plant Science, 84(2), 625-629.

Menzies, J. G., & Turkington, T. K. (2015). An overview of the ergot (Claviceps purpurea) issue in western Canada: Challenges and solutions. Canadian Journal of Plant Pathology, 37(1), 40-51.

The colour of clean – Top crop Manager