Ergot of Wheat

Claviceps purpurea

Claviceps species

Description:

Purple to black horn like bodies that replace grains in the head. Most species have bodies that are larger than the grain and protrude from the head, so they are usually easy to see at harvest. During flowering yellow droplets of sugary slime on the head are the first sign of the disease.
Ergot contamination in grain samples is more commonly due to Ergot of Annual Ryegrass or Darnel growing as a weed in the crop.

Species Affected:

Wheat, Annual Ryegrass, Cereal Rye, Darnel, Triticale.
Triticale and Darnel are particularly susceptible to Ergot.
Barley and Oats are moderately susceptible.

Biology:

Cool wet weather around flowering favours infection.
Ergots survive in the soil for up to a year and produce spores that infect open florets.
Infection is favoured by cool wet conditions at flowering.
Millions of asexual spores are produced in the slime droplets on the flowering head and are spread to adjacent plants by raindrop splash or insects that are attracted to the sugar or honeydew.
It only infects the ear of grasses and cereals.
It is more prevalent in open flowering species like Ryegrass and other grasses. Similarly Triticale and hybrid Wheat varieties are more prone to infection than other Wheat varieties and it is less common in Oats and Barley.

Life Cycle:


Courtesy of Dr Vicky Foster, HGCA.

Origin and History:

Distribution:

Ergot of Wheat is fairly rare in Australian grain.
Ergot in Ryegrass is more common.

Significance:

Very toxic to animals and humans.
Very low tolerance levels in grain for sale for both wheat and other ergots.
Poisoning can occur in livestock feeding on ergot-infected pastures, silage and hay; and grain. Levels of ergot should be kept to less than 0.02% of the feed weight if infested feed is used for livestock. Ergot infested grain should be mixed with clean grain and used as a supplement for stock with paddock feed. Be wary of graded seconds or grain from the bottom of silos where concentration of ergots may have occurred.
Clinical signs (lameness, gut pain, low intake of feed, rough coats, empty gut, off milk) are more pronounce in cattle than sheep.
Ergot contaminated cereal grains use to make flour also possess a risk to human health.

Management and Control:

Plant seed that is harvested from uninfected areas. If clean seed is not available then grade to remove as many ergots as possible.
Adjust crop rotation so that Wheat follows a broad-leaved crop or pasture.
Control grass weeds in crop and in the 2 seasons before crop with herbicides or other means to prevent flowering (e.g. hay, silage, topping, heavy grazing, fallowing)
Bury infected material more than 5 cm deep to prevent raindrop splash spreading spores.
Avoid planting infected paddocks to Wheat for at least year.

Related and Similar Species:

The same fungus infecting Wheat can also infect Annual Ryegrass, Barley, Darnell or Drake, Cereal Rye and Triticale
Ergot of Rye (Claviceps species)
Other Claviceps species can infect Paspalum (Claviceps paspali) and Phalaris (Claviceps phalaridis and Claviceps phalaris).

References:

1293

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.HerbiGuide.com.au for more information.