Ergot is a rising threat on the Prairies, and plant researchers are trying to figure out the best way to combat the disease.
“Everyone is concerned with fusarium head blight, but ergot is right up there in terms of danger,” said Jamie Larsen, a research scientist with Agriculture and Agri-Food Canada in Lethbridge.
Rye and triticale are most susceptible to ergot, but the disease also infects wheat and barley. In 2011, up to 30 per cent of Alberta wheat deliveries to the elevator were rejected or downgraded because of ergot. The fungal disease infects grasses during the flowering stage, destroying the flower and replacing it with an ergot particle known as a sclerotia.
Incidence has been steadily rising across the Prairies since 2004, possibly due to cooler springs, reduced rotations, and minimum or zero till.
Research scientist Kelly Turkington likens the disease to a “puzzle.”
“There are a number of different pieces and there’s nothing that is one huge piece that addresses all the issues with it,” said Turkington, who works at AAFC’s Lacombe Research Centre in Alberta.
Nor is there a silver bullet for dealing with it — and that includes fungicides.
“What they have found in some trials is that you can get a slight reduction in ergot, but for the most part, fungicide trials have not been effective in reducing ergot levels in grain and economically, it’s just not worth it,” said Jim Menzies, a scientist at AAFC’s Morden Research Centre.
“If you’re planning to go into a field, and you’re worried about ergot, you need to be thinking a year ahead,” added Larsen. “Once those sclerotia are there, you can’t control them.”
Spotting an infestation
Ergot can be found in the grasses around fields and in ditches. As the plant matures, ergot bodies fall to the ground. Those bodies germinate the following spring, releasing spores that land on florets, and then hijacking the florets to produce honeydew about a week after anthesis.
“Your field will be full of flies, which will be landing on the honeydew and going from head to head, and that’s how secondary infection is spread around,” said Larsen.
Twenty-five days after heading, producers will start to see black, finger-like protrusions growing outside of the florets.
To reduce the threat of ergot, producers should mow grasses in the ditches the year before planting a cereal crop, as well as the year they grow a cereal crop. Mowing is most effective just before flowering.
If the crop is infected, the outside edges of the field — which typically see the heaviest infestation — can be harvested separately. A rotation that is three years or longer also helps to break down the disease inoculum.
A strong nutrition program and doing what you can to encourage uniform emergence (late tillers are most at risk of being infected) are also recommended.
“The sooner the seed gets fertilized, the sooner it becomes resistant to infection by ergot,” said Menzies.
Eight days after fertilization, the plant can no longer become infected. It’s also important to take care with herbicide and pesticide application to prevent flowers from becoming sterile, as they are more susceptible to ergot.
Over the last couple of years, copper has been touted as a cure-all, which is not the case.
Livestock producers also need to be aware of the threat — especially if they are harvesting silage, swath grazing or standing grazing wheat or triticale — because cattle can get quite sick from eating ergot.
Plant breeders are trying to create cultivars resistant to ergot, but they aren’t available yet.