Ergot proved to be a major problem for some South Dakota wheat producers in 2011, apnd was common over a fairly wide area, says Bob Fanning, SDSU Extension plant Pathology field specialist.
"Ergot outbreaks are said to be very rare in wheat. The exact weather conditions needed to trigger the outbreak do not occur often, and it is very likely that the wheat crop will escape serious infection next year," Fanning said.
However, the ergot outbreak has raised the question about planting wheat that contains ergot.
"Control of ergot is said to begin with planting seed free of sclerotia," Fanning says. "With that said, this can be a challenge."
Certified seed can have no more than 2 percent maximum ergot sclerotia for the registered class and no more than 3 percent for the certified seed class.
"Seed producers typically do not want even that much, and wheat growers usually don't want it either," he say
Fields that had ergot in 2011 will likely have elevated levels of the survival structures (sclerotia) on the soil surface, Fanning says.
One practice that he says can help reduce the risk of problems with ergot, is to rotate crops, and not plant wheat in close proximity with these survival structures for one year, which is said to be the approximate life span of the sclerotia bodies. He adds that in order to maximize this practice's effectiveness, farmers need to be diligent about weed control.
"The effectiveness of rotation to a non-susceptible crop will be diminished if grasses and grassy weeds in ditches, fencerows, etc. surrounding the field were allowed to head the previous year," Fanning said.
Fanning also recommends growers avoid planting seed lots contaminated with ergot.
"Seed containing ergot can be cleaned to remove the sclerotia, which will help reduce the risk," he says.
Additional precautions he suggests include burning stubble and/or and using tillage to destroy or bury the survival structures.
"There are numerous modern studies that now show tillage treatments can actually help the bodies that survive to be brought to the surface by another tillage event in the future," Fanning said. "Tillage would be effective if it resulted in total burial - moldboard plow with no tillage at a similar depth in the future."
He discourages burning due to the loss of valuable residue and does not suggest applying a foliar fungicide at flowering, because the timing and the site of infection are so specific.
"The potential of fungicide seed treatment has been raised regarding control of ergot. There are however, no fungicide seed treatment products that are labeled for control of ergot, and no level of control can be guaranteed," Fanning said.
To learn more, contact Bob Fanning at Robert.Fanning@sdstate.edu or 605-842-1267.