Growers ponder plant growth regulators

Trials look at how PGRs respond to different cereal varieties, growing conditions and timing of application

Grain producers are already logging long hours in the sprayer, so the thought of making yet another pass over the same wheat field probably has limited appeal.

But what if one more pass with the sprayer had the potential to reduce lodging and boost wheat yields by five, six or even seven bushels per acre?

That’s why more farmers are asking questions about plant growth regulators, which have the potential to boost yields but are largely unproven in Western Canada.

“They’re not for everyone,” says Tom Tregunno, product manager with EngageAgro, which sells Manipulator, one of Canada’s most recently approved PGR products.

“They’re not for every field and they’re not for every area, but in some cases, they make a lot of sense, especially if you’re pushing for higher yields or if you’re on heavier ground and you have a history of lodging.”

PGRs regulate plant growth during a stage known as stem elongation.

They produce shorter plants with improved straw strength by regulating the production of naturally occurring plant hormones.

Although PGRs are beginning to generate interest among prairie farmers, total acreage in Western Canada is small.

Tregunno did not offer an estimate on how many acres were treated with Manipulator this year, but he said drought reduced use in Western Canada.

In addition to Manipulator, Bayer’s Ethrel is registered for use on cereals and BASF’s Cycolcel Extra is registered for winter cereals.

Manipulator, which was registered in 2014, was designed to give grain growers more flexibility in the timing of application and recommended application temperatures.

Data compiled by EngageAgro suggests plant height can be reduced by 10 to 15 centimetres in some varieties, and lodging can be significantly reduced.

Yield improvements of seven bushels per acre are not uncommon under growing conditions that include high fertility and ample rainfall, Tregunno said.

However, yield benefits are generally less pronounced under dryland conditions, particularly when moisture is a limiting factor and fertility rates are relatively low.

“If you’re only averaging 30 bu. per acre (on wheat), then a PGR is probably not for you.”

Manipulator costs $14 per acre when applied at the recommended rate.

It should be applied on wheat at the five to six leaf stage for maximum effect and can be tank mixed with fungicides and herbicides. However, application outside the recommended window is likely to reduce efficacy. In other words, a separate pass may be required.

Tregunno said EngageAgro has been assessing tank mixes and compatibility with commonly used herbicides and fungicides and identified no major problems, although surfactant burn could be a concern.

He said other lingering questions still need to be answered.

“PGRs have been used in Europe for more than 30 years, but they’re fairly new to Canada and there’s a lot we still don’t know,” he said.

“For example, we know there’s a variety response. In other words, some varieties tend to give a much stronger response than others. We also know that timing of application can affect how well they work. But we definitely think there’s a fit, especially as guys are getting more keen on technology and more interested in pushing their yields.”

Linda Hall, a professor and agricultural researcher at the University of Alberta, is hoping to answer some of the questions surrounding PGRs. Hall recently secured funding to carry out a multi-year project examining the efficacy of PGRs on different cereal varieties under different growing conditions.

The study will look at application timing and varietal responses.

Product efficacy will be examined on 30 varieties of cereals including wheat, barley and oats.

Small plot trials will be situated at two dryland locations in Alberta at St. Albert and Barrhead.

A third site will be established under irrigation at Lethbridge.

“The research is basically to (see if PGRs) fit into Western Canada and if so, where do they fit and what would be the other factors associated with their use,” Hall said.

“PGRs are not suitable for all growers or for all areas of Alberta or for all years,” she added.

“For example, this year would not have been a year where farmers would have applied a PGR because it was very dry in most areas, yields were down and plants were already shorter than usual.

“In other words, PGRs are not going to be a routine application every year for all growers.… But for growers that are wishing to maximize their productivity and have the appropriate moisture and variety, it may be something they want to consider.”

Hall’s research is among the first projects to take a critical look at the use of PGRs and their potential benefits.

Sheri Strydhorst, a research scientist with Alberta Agriculture, has also been studying the impact of PGR products for the past three years.

She said researchers and commercial grain growers are learning more about PGR efficacy, but many questions have yet to be answered.

“(These products) do not work the same on all cultivars, and I think that’s something that producers really, really need to know.”

Strydhorst has been assessing the performance of Manipulator over the past two years on 12 wheat cultivars in four classes: prairie spring, general purpose, soft white and hard red. The varieties were tested at five test sites in Alberta last year and again this year.

The most obvious responses were observed under irrigation on CWRS varieties.

Manipulator reduced the height of Harvest by 14 centimetres and reduced lodging to zero percent from 39 in the untreated check.

CDC Stanley saw a 13 cm height reduction and a 13 percent reduction in lodging to zero percent, while Coleman saw an 11 cm height reduction with lodging reduced to 30 percent from 70.

However, some CWRS varieties did not show any response.

“Manipulator worked wonderfully on a variety like Harvest … but I think the perception that (PGRs) are going to work the same on every wheat variety is absolutely not true and I think producers really need to be aware of that,” she said.

Strydhorst said producers who are considering PGRs should first ensure that they are in high moisture areas and that fertility rates are conducive to lodging.

After that, they should try to determine whether the cultivar they are growing is responsive to PGRs.

Growers should also ensure that no marketing issues are likely to arise. Earlier this year, Saskatchewan Agriculture published an article that urged farmers to be aware of potential marketing problems and to ensure that grain buyers will accept grain that’s been treated with PGRs.

“While new products like Manipulator may be of interest agronomically, using new products may cause problems with marketing the grain,” the article said.

“Manipulator is currently approved in Canada but not in all markets of Canadian grain. When an export market has not established maximum residue limits for a crop input like pesticides or PGRs, grain treated with that product cannot be exported to that country.”

Tregunno agreed that growers considering Manipulator should research the product first, talk to others who have used it and make an informed decision. New growers are advised to test the product on a portion of their acreage and assess the benefits.

“If you’re new to this, always leave a check,” said Tregunno.

Contact brian.cross@producer.com

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