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Feeding yield, not disease

Agronomist Peter Johnson explores what he calls the synergy between nitrogen and fungicide and what it means for yield

Agronomist Peter Johnson thinks fungicide and nitrogen are a match made in heaven and a late fungicide pass may help bolster yield in wheat.

Johnson, of RealAgriculture, turned his talk to wheat yield during the recent BASF Knowledge Harvest event in Brandon. The cereal has become a gap filler in between crops like soybeans and canola, he said, a state of affairs that he would like to see changed.

Johnson suggested late fungicide application (unless there is disease concern early in the season) to keep crop green and filling for as long as possible. The practice will require the crop to be desiccated, he admitted, putting the ideal desiccation date when the peduncle, or upper stem just under the seed head, yellows.

A fungicide pass may also save producers from disease trouble after fertilizing, according to Johnson. Nitrogen meant to feed the crop may also benefit the fungi, either directly or through environment as the newly lush growth makes for a more favourable habitat.

Peter Johnson.
photo: Alexis Stockford

“Really, nitrogen is the driver,” he said. “The problem is, as you add more nitrogen, you run into other issues. Lodging is one. Disease is the other one, so realistically, if we want to get that yield out from the nitrogen — we want to utilize the nitrogen — it’s all about keeping the plant healthy so that it has the leaf tissue to photosynthesize and take that nitrogen and turn it into grain yield.”

Not all crops see the same yield-boosting benefit, he added, although cereals have reacted well.

High yield, high nutrients

Provincial experts argue that producers are not using enough nitrogen to unlock the genetic potential in their wheat.

John Heard, crop nutrition specialist with Manitoba Agriculture, points to new, higher-yielding wheat varieties that have burst onto the scene, while fertilizer use has not always kept up.

While Heard acknowledges farmer concerns with too much nitrogen, lodging and economic risk among them, he says some producers are splitting application to help deal with those risks.

“They’re putting on a good base rate of nitrogen and then they’re maybe assessing the crop and saying, ‘No, this crop has extra yield potential,’ and they will do some in-season application,” he said after a soil fertility update in Brandon Jan. 30-31.

Johnson agreed that higher-yielding wheat will need more nitrogen to meet genetic yield potential. Phosphorus will raise another challenge, he said, since new varieties will also take up more of that nutrient, but extra phosphorus also comes with environmental concerns.

“Big yields take bigger nutrients out of the field. They remove more, so you have to apply more,” Johnson said. “As you apply more, even though it genetically has more yield potential, it still gets that disease, so it becomes even more critical on high-yield varieties to have that fungicide in there, because we just don’t have good enough genetic resistance.”

Like Heard, the RealAgriculture agronomist pointed to split nitrogen application, not only to mitigate economic risk, but to jump-start development during pollination and the next 14 days, a period Johnson says is critical to maximize kernel numbers and fill in wheat.

Johnson also addressed delayed-release nitrogen fertilizers, something that may also spread the nutrient’s impact, but faces concerns with consistency, since weather will impact that release, he said.

About the author

Reporter

Alexis Stockford is a journalist and photographer with the Manitoba Co-operator. She previously reported with the Morden Times and was news editor of  campus newspaper, The Omega, at Thompson Rivers University in Kamloops, BC. She grew up on a mixed farm near Miami, Man.

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