• Plant Health
  • Feb 28, 2022

Are Plant Growth Regulators Worth the Investment?

Growers evaluating early-season soybean stands.

Plant growth regulators have been getting more attention from the agricultural community in recent years, but you may be wondering if they actually live up to the hype. The Answer Plot® program has generated some solid research supporting the benefits of applying plant growth regulators (PGRs) both in-furrow at planting and later in the season as a foliar application. If you haven’t added a PGR to your crop nutrition program, now may be the time to start.

What do PGRs do?

PGRs are hormones that regulate the growth and development of plants. There are five basic classes of plant growth regulators, each with a different effect on plants, ranging from stimulating plant growth to dictating seed germination. Plant responses may vary depending on PGR type, rate and application timing.

  • Auxin: Key regulator of plant growth and development that causes biological responses, such as flower formation, fruit set and growth, and root and stem growth.
  • Gibberellins: Regulator of key processes in the plant that’s used to stimulate cell division and elongation, break dormancy and speed up seed germination.
  • Cytokinins: Plant hormones that stimulate cell division.
  • Ethylene: Plant hormone induces ripening, causing leaves to droop and drop. Often a result of stress.
  • Abscisic acid: Plant-growth inhibitor that induces dormancy, prevents seed germination and causes stomata to close. 

When should you apply a PGR?

Plant growth regulators can be applied throughout the growing season. To promote vigorous root growth and early emergence, PGRs can be applied as a seed treatment or in-furrow at planting. The benefit of using a PGR prior to emergence is that seeds get an extra boost and a strong start at a time when soil and environmental conditions might not be favorable.
Ascend® SL plant growth regulator by WinField® United contains three EPA-registered active ingredients for more vigorous emergence, better root growth, wider leaves and thicker stalks. Answer Plot data from 199 sites over three years showed 60.5% of sites responded positively with a 5.85 bushel per acre positive response when Ascend PGR was applied in-furrow to corn at planting.
Applying a foliar PGR prior to tasseling in corn can help stimulate plant growth and development to harness more energy for grain fill. An application at V4 to V6 in corn makes sense because you’ll have a better idea of your crop’s yield potential and can focus PGRs where you’ll get the best potential return on investment. Answer Plot data from 13 locations in 2017 showed an average 2.8 bushel per acre yield advantage when Ascend SL was applied as a foliar application at V4 to V5 in corn west of the Mississippi River.
Based on multiyear field trials, farmers can expect to see improved plant health with our newest PGR, Ascend Pro. Like Ascend SL, Ascend Pro contains an optimal blend of three PGRs: auxin, cytokinin and gibberellic acid. It also contains a proprietary amino acid derivative to help optimize performance and consistency across a variety of weather conditions, including cold, wet and dry weather.
In 2018, we saw a very consistent, positive yield response 76% of the time when Ascend Pro was applied at planting. The optimized formulation of Ascend Pro has worked in every geography tested to offer an early-season plant benefit.

Aren’t all PGRs the same?

PGR is a broad term for any product that uses plant hormones to generate a plant response. PGRs can initiate many responses in plants, from more vigorous root growth and stem elongation to plant senescence. Therefore, not all products provide the same results. Before you invest in a PGR, be sure you know what the active ingredients are and what the expected plant response is.
It’s important to remember that more active ingredient does not always mean a better plant response when applying PGRs. Always ask for firm data to back up any product claims.
To learn more about PGRs and where they fit into your management plan, talk with your local WinField United retailer.
All photos are either the property of WinField United or used with permission.

© 2022 WinField United. Important: Before use always read and follow label instructions. Crop performance is dependent on several factors many of which are beyond the control of WinField United, including without limitation, soil type, pest pressures, agronomic practices and weather conditions. Growers are encouraged to consider data from multiple locations, over multiple years and to be mindful of how such agronomic conditions could impact results. Answer Plot, Ascend and WinField are trademarks of WinField United. All other trademarks are the property of their respective owners.

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