Check for Ergot!
Have you ever heard of ergot? This is a small, hard, black fungal body, created by Claviceps purpurea, that can develop in the seed heads of certain grass species. The ergots contain toxic alkaloids that can have negative impacts on equine health. There is limited research that has been done on ergot in horses, but a recent ADAS review conducted into Ergot in cereals casts some light onto things we as equestrians should look out for in our pastures.
Ergot in Cocksfoot (Source: Phil Bounds ADAS)
In fields that have been grazed all year round and have short grass, ergot is unlikely to cause an issue. However, it is still important to check around fence lines where long grass with seed heads may be growing, and strim where there is a problem
The current trend for either late harvesting of hay crops or leaving grass to grow long as standing hay for winter means that there is an increased risk of horses coming into contact with ergot.
What to look for
Walk your areas of long grass and check the seed heads to see if you can see what look like small mouse droppings where the seed should be. The ergots will take different shapes in different species of grass.
Factors affecting ergot development
- Ergot germination in the spring is favoured by warm wet conditions, this is when the dormant ergot in the soil releases its infectious spores.
- Ergot is most likely to form in grasses when weather conditions are cool and damp when the grasses come into flower (usually in late May to early June).
- Grass species – some grasses are more prone to infection than others. The ADAS report includes a table of grass species and the information that is know as to their relative risk of infection. High risk grass species include; meadow foxtail, cocksfoot, tall fescue, timothy, false oat grass and common bent, with rye grass being of intermediate risk.
Actions to prevent ergot (adapted from AHDB’ Updating UK management guidelines for ergot (a review) authored by ADAS)
- Ensure grass has adequate nutrition – copper and boron deficiency in cereals is linked to increased susceptibility to ergot infection.
- Check the pH of your soil – availability of boron decreases as soil pH increases, and boron deficient crops can be more susceptible to ergot.
- Where fields have a history of ergot infection preventing the grasses going to flower through mowing or grazing early in the season will eliminate risk. Ergot is known to survive for at least one year, occasionally up to 3 years, in the soil.
Managing ergot
- If you find ergot in your pastures remove horses to prevent ingestion.
- Top infected pastures and delay grazing until topped material has broken down and ergots are in the soil, then keep pastures topped or grazed in future years to prevent reinfection.
- If hay crop harvests are delayed ensure you check for ergot before cutting to ensure it does not get into conserved forage.
- Where pastures have a history of ergot consider overseeding with lower risk varieties.
For more information about ergot risk (in cereal crops) see the ADAS report linked below.