The symptoms of fusarium head blight in cereal crops are classic. Portions of the heads appear bleached, blighted and straw coloured.
But while it’s easy to detect fusarium in wheat and barley, it’s not so easy in oats.
Commercial oats tend not to show symptoms of the disease until the crop is practically in the bin.
Exactly why is a bit of a mystery. Perhaps fusarium takes longer to develop in oats than in other cereal grains. By the time symptoms begin to appear naturally, the oats are already starting to mature.
For that reason, an early-warning system for fusarium in oats is frustratingly out of reach for farmers, according to Andy Tekauz, an Agriculture and Agri-Food Canada plant scientist.
“Unfortunately, there’s not really very much they can do,” said Tekauz, head of cereal diseases at AAFC’s cereal research centre in Winnipeg. “That’s why we’re working toward improving the resistance in oats.”
Tekauz presented an update on fusarium research in oats during a recent crop tour at the University of Manitoba hosted by the Prair ie Oat Breeding Consortium.
Fusarium isn’t as big a problem in oats as it is in wheat and barley. Still, oats can get the disease and it can also develop mycotoxins in the kernels, he said.
The most common mycotoxin found in grain affected by fusarium head blight is deoxynivalenol or DON. Besides reducing feed intake by livestock, DON can adversely affect the baking quality of wheat and the malting and brewing qualities of malt barley.
Fortunately, DON levels in oats are not that high – about one part per million (ppm) at maximum, said Tekauz. One ppm is considered the acceptable threshold level for DON in feed grain fed to pigs. Cattle and horses are more tolerant to DON.
Another bit of good news is that oats, unlike wheat, does not have the hull removed at harvest. If oats has fusarium, most of the inoculum is in the hull, which is removed when oats is processed for food. Also, DON is water soluble, so steaming and rolling will remove any fusarium which may be left in the groat.
Still, the fact remains that oats, being a cereal crop, can get fusarium and it’s difficult to detect its presence before harvest.
But it is not impossible. Tekauz said producers who want to know if they have the disease in their oat crops can check the regularly updated Fusarium Head Blight Risk map on the Manitoba Agriculture, Food and Rural Initiatives website.
If risk conditions are high during a week in which a crop is heading, chances are it will later show signs of fusarium, said Tekauz. “If fusarium head blight were present and plainly visible in a wheat or barley crop on a producer’s region between heading and maturity, an oat crop in the same location would likely also be affected.”
AAFC plans to conduct its annual fusarium survey in Manitoba during the first two weeks of August. Spring cereals in fields from Steinbach to Virden will be sampled at random. Results should be available later in the month.
A recent winter wheat survey found little fusarium, due to a cool spring which hindered the development of any inoculum that overwintered.
Tekauz said fusarium-resistant oat varieties are still eight to 10 years away. Other cereal crops are doing better. Several wheat varieties now have moderate fusarium resistance. A recent barley variety, CDC Mindon, has improved resistance. [email protected]