More research, rules needed on plant growth regulators

Plant growth regulators could be an important tool for high input cereal growers, but officials are urging farmers to move slowly. 

Interest in PGRs has been high since Engage Agro’s Manipulator, which has the active ingredient chlormequat, was approved for use in Canada last year in spring and winter wheat crops. 

The product is intended to produce a crop with shorter, thicker stems to fight lodging and protect yields and is approved in most wheat growing countries.

However, Manipulator doesn’t have a maximum residue limit in the United States, which means wheat crops on which it is applied won’t be allowed to enter that country. 

Cereals Canada has warned that “it is unlikely that these approvals will be in place before the 2015-16 crop is exported.”  

Until the issue is cleared up, growers experimenting with the product are advised to first consult with grain buyers.

“I know there’s certainly concern out in the industry, as there should be,” Sheri Strydhorst, an agronomy research scientist with Alberta Agriculture said in a telephone interview. She said she fielded multiple requests this winter to talk to producers about PGRs. 

At an agronomy workshop in Watrous, Sask., last week, farmer Ed Thibault said he was eager to “play” with PGRs, but that the U.S. access issue was a “deal breaker.”

However, he does see potential for the product on his 3,000 acre farm in the Rural Municipality of Invergordon. 

“We’ve had some wetter years, at least where I farm, and moisture actually hasn’t been limiting, so that leads you to a situation where you could push yields higher by adding fertility, but it doesn’t help you to add fertility if the whole damn thing lays down and makes a mess,” he said. 

Strydhorst said PGRs are promising, but researchers have yet to determine what varieties perform best, how protein content is influenced and how PGRs are affected by climatic conditions.

For example, Manipulator’s label warns against using the product in crops under stress from water, drought or nutrient deficiency, which can lead to yield losses.

In Watrous last week, Jessica Pratchler of the Northeast Agriculture Research Foundation in Sask-atchewan, said further studies are needed to examine variety selection, seeding rates, fungicide applications, root development and water use efficiency and how they relate to PGRs.

“When I looked at the large scale data that the industry has put out, to me there is no magical variety that works best across every factor,” she said.

“When you look at red spring (wheat), it looks like the height reduction is the greatest in tall varieties, whereas in durum the shorter varieties are shortening more. Planting a lodging resistant cultivar doesn’t appear to provide any additional benefit. That just goes to show that environment is playing a much larger factor than variety selection.”

Strydhorst said PGRs aren’t for every grower and should be used only in situations where lodging is a problem. They shouldn’t be used in dry regions that are seeing lower yields but hold potential for irrigated growers and those pushing yields to 100 bushels and beyond. 

“We don’t have widespread lodging, but if you’re in a situation where you have high nitrogen, high moisture, I think this is going to be an excellent risk management tool,” she said. 

PGRs have been used in Europe for decades in horticulture and cereal production. 

Pratchler said researchers looked at PGRs in the 1980s, but low cereal prices discouraged use.

“It kind of fell to the wayside, but as you know, you’re trying to get more and more of the yield out of your crops, so you’re willing to apply more and more, so PGRs have come back onto the playing field,” she said. 

Etherel from Bayer CropScience had been suggested for use in Western Canada but is no longer recommended because of a short application window, after which growers could damage their crops. 

Pratchler said Manipulator has a larger window for applications, making it “more flexible.” She said growers could make applications from the two to three leaf stage — “typical herbicide timing” — up to the early flag leaf stage. 

The best results have been found at growth stage 31 when applied at .73 litres per acre. 

“That means an extra field pass because that falls directly in between your common herbicide and fungicide timings,” said Pratchler. 

Strydhorst said timing remains important with Manipulator. 

“You really want to target growth stage 30 to 32, and that can be a two to three day window,” she said.

“Staging is not anything like herbicides.… You need to be pulling out plants, cutting the base of the plants and looking at how nodes are moving to get this staging right.”

Engage Agro’s large scale trial data found the greatest height reductions in CWRS varieties, which saw a 10 percent height reduction 83 percent of the time and a 10 percent yield gain 55 percent of the time. 

Pratchler said small plot trials conducted by NARF and the Indian Had Agricultural Research Farm have found positive results in Canada Western Red Spring and Canada Western Amber Durum crops. 

Pratchler offered an economic breakdown on Manipulator’s performance at a price of $13.84 per acre and assuming a $5 per bushel price for wheat. She said yields needed to increase 2.8 bu. per acre in CWRS for producers to break even, which is achievable. 

Producers are also likely to break even on durum crops, she said. 

“You’re more than likely going to at least cover your minimum line,” she told producers in Watrous.   

Producers interested in PGRs are advised to start small, using strip trials or experimenting on one quarter.

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