Intensifying Production on the Prairies – Plant Growth Regulators

Plant growth regulators (PGR) are not a new technology, only relatively new to the Prairies. Where high intensity cereal management systems, specifically high levels of nitrogen fertilizer, are being used and lodging is a threat to yield and quality, plant growth regulators are commonplace, such as in Europe.

Almost 90 percent of winter wheat acres and 75 percent of winter barley and winter oats have a PGR applied in the U.K.

PGRs act to shorten the plant stem and increase resistance to lodging. “Research in the EU and by Alberta Agriculture shows that small changes in plant height can have a strong influence on lodging resistance,” explains Phil Bernardin, technical representative with Engage Agro, a supplier of pest control products for horticultural, specialty, and other unique markets in Canada. “We see an opportunity for PGRs on the Prairies and that is why we pursued the registration of our PGR product, Manipulator, and why we are now working on establishing MRLs with the U.S.” At this time, wheat treated with a PGR in Canada cannot be exported to the U.S. as there are no maximum residue limits established. It is hoped the MRLs might be in place for growers to safely use a PGR in 2018.

PGRs work by interrupting or altering the balance of phytohormones in the plant which changes the plant structure or architecture. PGRs exploit plant biology to strengthen stems, alter plant architecture, and manage ripening of fruits.

In cereals, PGRs reduce stem elongation reducing the height of the plant. “Our product, Manipulator, is an anti-gibberellin,” says Bernardin. “By reducing gibberellin biosynthesis, it interrupts plant signals involved in stem elongation. Growers can expect to see reduced crop height of four to six inches.”

By artificially reducing crop height, more nutrients, water, and energy are available for grain production and the shorter, stronger stem is more resistant to lodging allowing growers to get that extra production off safely and in the bin. “If farmers can reduce lodging in their crops, then they are increasing yield potential,” says Bernardin. “They are also reducing their risks of uneven maturity and loss of grain quality as well as making harvesting a lot easier.”

“The optimum time to apply Manipulator is at the start of stem elongation (five to six leaf stage) for excellent results,” says Bernardin.“Very good results are also achieved at flag leaf when fungicides are applied. Typical herbicide timing or the three to four leaf stage with 1 tiller produces the least effective response. Research results from Indian Head Agricultural Research Foundation in Saskatchewan, and from various sites in Alberta, are showing consistent height reductions in wheat as well as reduced incidence of lodging.”

“Manipulator is in use primarily with seed growers or growers who are producing wheat for ethanol production – guys for whom MRLs are immaterial at this point,” says Bernardin. “While we wait for MRLs, we are continuing our research investigating impacts on different classes of wheat.”  Manipulator works very well on Canada Western Red Spring and Canada Western Amber Durum varieties. “It doesn’t seem to be as effective on Canada Prairie Spring wheat varieties,” says Bernardin.

The key advantage of a plant growth regulator like Manipulator is to allow a grower to push harder with his agronomic package, increasing fertilizer rates while at the same time reducing the risk of lodging.

At trials this past summer in Indian Head at the Indian Head Agricultural Research Foundation, Engage Agro found that Manipulator reduced the height of all the varieties in the trial significantly and it increased the resistance to lodging very significantly. In addition, all the treated entries yielded significantly better than the corresponding untreated check. This trial was seeded into canola stubble and was fertilized to 125 percent of the soil test recommendation.

Stay tuned for developments on the establishment of MRLs for Manipulator over the next 18 months and talk to your agronomist about how this product might work for you.