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Winter wheat seed: treatment pays

A dual fungicide/insecticide seed treatment builds hardier winter wheat stands

Despite the benefits of winter wheat — weed competitiveness, high yield potential and a schedule that allows growers to spread out work load and capital costs — it’s still not a staple crop for many western Canadian farmers. Farmers say concerns about planting logistics and poor stand establishment are obstacles to growing winter wheat.

To find solutions, several researchers worked together on a two-part study testing different winter wheat agronomic practices at nine locations across the western Canadian prairies over three years.

As with most research studies, the outcomes don’t provide a magic bullet solution — results and recommendations are highly complex and can vary from region to region. But Dr. Brian Beres, Agriculture and Agri-Food Canada agronomy research scientist at Lethbridge, Alta., does recommend using a seed treatment with a dual fungicide and insecticide to get the best results from your winter wheat.

Seed treatments and winter wheat

In Part 1 of the study, a research group including Beres and headed up by Dr. Kelly Turkington, AAFC pathology research scientist at Lacombe, Alta., looked at the impacts of seed treatments and fall-applied fungicide on winter wheat during the 2011, 2012 and 2013 growing seasons.

Researchers compared five combinations: a check of no seed treatment, two different single fungicides, a single insecticide, and a dual treatment that included both fungicides and the insecticide. Not surprisingly, the comprehensive package yielded the best results, Beres said, “Both from a crop response standpoint as well as a net return standpoint.”

This comprehensive treatment included a combination of Bayer CropScience’s Raxil 250 FL, a Group 3 fungicide with the active ingredient tebuconazole; Bayer’s Allegiance FL, a Group 4 fungicide with the active ingredient metalaxyl; and Bayer’s Stress Sheild a Group 4A insecticide, a neonicotinoid with the active ingredient imidacloprid. This combination is sold by Bayer as Raxil WW.

Researchers also tested each of these five seed treatment options both with and without a fall-applied foliar fungicide — Bayers’ Proline 480 SC, with active ingredient prothioconazole, a Group 3 fungicide, applied at the three- to four-leaf stage with surfactant Agral.

In every situation, they seeded CDC Buteo seed with a Conserva Pak air drill with a Valmar air delivery system and knife openers spaced 23 cm apart. They used a seeding rate of 450 seeds per square metre with fertilizer at soil test recommended rates and weed control as necessary at label rates.

Results were generally consistent across all of the sites: the highest net returns came from using the full package of dual fungicide and insecticide seed treatment, without the fall-applied foliar fungicide. The fall application increased yield and plant stand stability, but the added cost of buying and applying the fungicide lowered overall returns, based on wheat prices of $5.25 per bushel.

At sites where stripe rust had been confirmed in the fall, yield gains were more apparent where the fungicide was applied. “But,” Beres said, “net revenues compared to not applying any foliar fungicide were still cost prohibitive.”

The study says, “Crop responses to seed treatments can extend beyond mitigation of pathogens or insect pests.” For example, previous work has found that prothioconazole can improve plant frost tolerance and the active ingredient tebuconazole can cause physiological changes in plants that improve root development.

In further work, these researchers want to study the study the benefits of spring foliar fungicide application, as opposed to fall application.

The second part

While Part 1 established the that the dual fungicide/insecticide combination provided the greatest net returns, in Part 2, Beres says, researchers added seed treatments “into a more complex agronomic system, a system that involves levels of seed vigour, where we’re using three levels of seed size as a proxy for vigour, and integrating that with two levels of the seeding rate, a high and low.”

These variables were used to imitate different agronomic system scenarios, “from weak through to very strong. What we know is, if you’re in a compromised situation of any kind, which we created by using a poor seed lot (thin, light seed) and a lower seeding rate, the dual fungicide/insecticide created a very positive impact with respect to a mitigation strategy.”

Researchers concluded that the combination fungicide/insecticide package could improve plant establishment and increase yield in a thinner winter wheat stand. “The surprise to us,” Beres says, “was in those low plant stands is how a seed treatment actually improves plant stands in spring and protected yield even in the absence of a pathogen or insect.”

Farmers with stronger agronomic systems may find that the net returns from the fungicide/insecticide combination aren’t as obvious. However, while they may not increase benefits in a particular year, they may help promote more stable plant stands and crop yields over time.

“From a very strong agronomic system, what we then would conclude is that, while it’s not as apparent, it definitely is something that would provide the grower with the insurance of protecting yield and stabilizing yield year after year,” Beres says.

Overall, researchers found the highest net returns came from using low seeding rates with the dual seed treatment. However, this left room for more weeds, and required an additional herbicide application, lowering overall profits. Thinner stands also led to more tillering, causing uniformity issues and the crop to mature later, adding to harvest hassles.

Conclusion

“Before we initiated these studies,” Beres says, there was anecdotal evidence that with a coating on the seed, perhaps water wouldn’t imbibe as readily and germination and emergence would subsequently be delayed. This would be especially problematic for winter wheat, “when you want something to pop out fast, and have lots of vigour and actively grow for that short period before fall closes in.”

“Or,” Beres says, “there was the flip side: actually [seed treatment] might create a response and get things moving earlier.” That was what happened.

With seed treatments, Beres says, “You do actually change processes within the plant. Various active ingredients in seed treatment will affect certain metabolic pathways in that plant to make it more vigorous. It’s a very practical and useful management tool for protecting yield.”

These two studies are the type of work that provides hands-on results for growers. This work was spearheaded by Ducks Unlimited Canada and other industry partners. “There are a lot of really progressive farmers out there, and as an agronomist, I’m fortunate to work with many of them. Many of them are leading edge, early adopters that have very strong agronomic systems.”


Read the research

In the world of scientific research, many published papers are hard for non-scientists to track down, and you often have to pay to read them.

However, the work published by Agriculture and Agri-Food Canada researcher Dr. Brian Beres is available to the public with no charge.

The easiest way to find the two studies referenced in this story, and the rest of Beres’ research, is to take a look at his (long) list of research publications. If you type “Brian Beres research” into Google (don’t add the quotation marks), you’ll be led to his AAFC directory page. You’ll find Beres’ research interests, current projects, and the list of links to all of his recent publications. You can follow these links through to the full texts of all of his research papers.

This is a handy way to find the complete information for any work published by federal researchers.

Get the latest news

Interested in the latest regional research?

This fall, Agriculture and Agri-Food Canada started sending out monthly emails rounding up the latest “Science News From the Prairies.” The September issue featured a piece about the rotational effects of pulse crop residues. In October, a link led to an article about the potential for leaf spot severity to increase in the Prairies with changing climate conditions.

Get this research round- up in your email inbox for free. Just send an email to [email protected] and they will add you to the list.

About the author

Editor

Leeann Minogue is the editor of Grainews.

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