Plant growth regulators are picky about staging — and varieties

Research is underway to find which cereal cultivars respond to plant growth regulators

Plant growth regulators are picky about staging — and varieties
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Lodging is a serious issue for crop growers — but plant growth regulators may not be the cure-all producers are hoping for, depending on the variety that’s being grown.

“What we really need to do is find a solution for standability, and plant growth regulators may be one of those agronomic tools that we can use to help improve standability,” provincial research scientist Sheri Strydhorst said at CanolaPALOOZA in late June.

“But what we’re finding is that the plant growth regulators don’t work on all cultivars. We might have something like CDC Go or Harvest wheat where the plant growth regulator works really, really well. You put it on Foremost or Thorsby or Coleman wheat and it doesn’t achieve you anything.”

That uncertainty makes it tough for producers to decide whether plant growth regulators — which reduce the height of a plant to limit the potential for lodging — are worth the risk, said Strydhorst. Luckily, trade issues around plant growth regulators are “managing the risk.”

“Manipulator does not have a maximum residue limit into the United States. Growers are hesitant to use it at all because if they can’t sell their wheat, they’re not going to use it,” she said.

“The good thing for us researchers is that gives us time to do some of that work.”

Provincial research scientist Sheri Strydhorst is looking at the link between cereal varieties and plant growth regulator effectiveness. photo: Jennifer Blair

Right now, Alberta researchers are looking at which cultivars respond to plant growth regulators, and which don’t.

“We want to make sure that growers using a plant growth regulator get the results that they’re looking for,” said Strydhorst.

In addition to wheat and oat cultivars, Strydhorst’s team is also looking at barley cultivars.

“Lodging in barley is a huge, huge issue. Manipulator is registered right now for use on wheat, and we’ve tried it on barley, which it’s not registered for. It doesn’t improve the standability,” she said.

“But new actives like trinexapac-ethyl that are in the process of registration are working much, much better. When that is registered, barley growers will have an option there, which would be really great for improving standability.”

The study started earlier this summer, so preliminary results on which cultivars respond to the plant growth regulators should be available this fall.

“Sometimes what we see is a plant growth regulator can look good two weeks after you’ve sprayed it, but by the end of the growing season, that plant might actually be taller,” said Strydhorst. “So we need to really wait until harvest to get that definitive answer.”

In the meantime, producers should make sure they “do their homework.”

“Talk to people who have been working with them or even your neighbours who have found something that’s worked,” said Strydhorst.

“With plant growth regulators, the staging is very, very critical to get them to work. If you have heat stress, drought stress, or waterlogging problems, we have seen yield reductions of up to 10 per cent. They’re picky.

“It’s not entry-level agronomy, and you’ve got to be watching your staging. It’s all about being careful.”

About the author

Reporter

Jennifer Blair

Jennifer Blair is a Red Deer-based reporter with a post-secondary education in professional writing and nearly 10 years of experience in corporate communications, policy development, and journalism. She's spent half of her career telling stories about an industry she loves for an audience she admires--the farmers who work every day to build a better agriculture industry in Alberta.

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