WATROUS, Sask. — There’s good news and bad news when it comes to fusarium head blight.
Many Saskatchewan fields are still recovering from several years of saturated soils, and farmers can expect to see the disease again this year, says Stewart Brandt of the Northeast Agriculture Research Foundation in Melfort, Sask.
However, while genetic resistance to fusarium head blight isn’t as strong in wheat varieties as it is for other diseases such as stem rust, researchers have been honing fungicide timings with positive results.
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“The challenge really is to select a variety with all of those desirable traits, yield lodging protein content disease and insect resistance,” Brandt told an agronomy workshop in Watrous, Sask., last week.
“I would suggest that when it comes to fusarium head blight, you probably want to put more weight into some of these other factors than you do into fusarium head blight resistance.”
He cited trial data that found two varieties, Unity VB and Shaw VB, responded similarly following fungicide applications, despite Unity’s better rating.
“My suggestion would be maybe we should be just picking a variety with good yield potential and protect it with fungicides,” said Brandt.
More data is needed on newer varieties such as Car berry, he added.
Saskatchewan Agriculture says a two-year break from wheat in a rotation is preferred to help control the disease because the fungus can over-winter in stubble.
“I suspect that in areas where fusarium head blight is a serious problem, the economic loss associated with grade loss is far larger than the yield loss,” said Brandt.
“Certainly in the area around Melfort … that’s the impression that we get.”
Shorter canola-wheat rotations have been identified as a contributing factor in spreading the disease, which thrives in moist, warm conditions at the heading stage.
“Extending it one more year between wheat crops will have a big impact on a lot of diseases, but the question is, what’s the relative importance of extending rotations one more year or two more years compared to fungicides, compared with some of the other practices we might use?” said Brandt.
“I know it’s better. How much better is it? Will it improve quality by one grade level? I can’t answer that. Those are the kinds of things we need to address because those I think are becoming more critical issues now than, ‘when should I put my fungicide on.’ We know some of those answers.”
Fungicide applications are advised if growers have experienced losses to the disease in recent years or forecasts are favourable for it to prosper.
Brandt said research conducted through the province’s Agri-ARM program had determined that a fungicide application at 75 percent head emergence to 50 percent bloom is usually just as effective or better than an application at the flag leaf stage.
Applying at head emergence resulted in yields averaging 70 bu. per acre in 21 comparisons over 11 location years. The application at flag averaged 65.5 bu. per acre, while the untreated crops yielded 61.2 bu. per acre.
Researchers also found results that discouraged dual applications, with some exceptions. Brandt said low plant density that resulted in a broad range of emergence can make a single application difficult to time.
“Dual fungicide applications are usually not better than single applications, but there are cases where they are, and one of those might be glume blotch or wherever you know in advance that you have severe fusarium pressure.”
dan.yates@producer.com
