Manipulator PGR Available for Use on Barley

Starting this growing season, plant growth regulator (PGR) Manipulator will be available for use on barley in Canada. The PGR, which was previously only registered on wheat, can help increase yield by reducing plant height an improving straw strength. Regarding the Keep It Clean program, it’s important for farmers to note that Manipulator will carry a ‘no recommendations/ green’ classification for feed and silage barley, but a ‘be informed/ amber’ classification for malt barley. Belchim Canada recommends that farmers who are growing malt barley under contract should discuss the use of Manipulator on barley with their grain buyer. Farmers who are growing barley without a contract, but intend to sell it as malt, are also encouraged to discuss use of Manipulator with potential buyers. For more information regarding Manipulator and barley market access, see the Keep it Clean website at:

Staging and application rates

Manipulator (active ingredient: clormequat chloride) should be applied prior to the stem elongation stage. Application of a PGR at this stage will signal the plant to begin redirecting resources from stem elongation to other processes, allowing for reduced height and potentially thicker stems and roots. Label directions for Manipulator on barley outline two application strategies:

  1. A single application between growth stages (GS) 30-39 at a rate of 0.9 L/ac. GS 30 is the beginning of stem elongation. To correctly stage your crop, fold back the leaf sheaths and count the ‘bumps’ caused by each node. By GS 33, all three nodes will be detectable, and by GS 39, the flag leaf will be completely visible. This is similar to the recommendations for a single application on wheat, where the optimal window is between GS 30-39 at a rate of 0.7 L/ac.
  2. A split application with the first pass between GS 12-32 and a second between GS 32-39, at a rate of 0.45 L/ac. GS 12 represents the two-leaf stage. The second leaf is considered completely emerged when its leaf collar is completely emerged from the sheath of the first leaf. The window for the first application is open until GS 32, when two nodes can be felt on the main stem. The second pass can be made between GS 32, and GS 39, when the flag leaf is completely visible and unrolled. Split application recommendations for wheat outline a first pass at GS 22-23 at 0.3 L/ac and a second pass at GS 37-39 at 0.4 L/ac.

Label directions also indicate that a total of 0.9L/ac should not be exceeded in a single year, and that a full rate of Manipulator should NOT be applied if your crop is stressed from water-logging, drought, or nutrient deficiency. For full label directions, see the 2020 Guide to Field Crop Protection:

Effect of PGRs on yield and other agronomic characteristics

Research on agronomic practices to maximize feed barley yield and quality found that application of Manipulator increased both grain yield and starch. The research project, led by Laurel Thompson of Lakeland College, found that starch was increased by an average of less than 1%, while yield was increased by an average of 2.2%. The yield increase was attributed to higher test weight at lower plant densities (22 plants ft-2) but was attributed to longer spike length at higher plant densities (32 plants ft-2). It was also observed that the decrease (1.3%) in plant height from the PGR application did not reduce lodging, even under different plant densities. However, a significant yield increase of 9.3% was observed when a PGR application was combined with post-emergence nitrogen fertilizer and a dual fungicide application. The study suggests that genetic resistance to lodging is the most effective method for Canadian barley producers. Other research from around the world has reported both increases and decreases in grain yield from PGR use, indicating that performance is dependent on many factors including crop type, variety and the environment.

Similar results were discovered by Dr. Breanne Tidemann of AAFC-Lacombe, Alberta. The study looked at agronomic traits, yield and quality effects of a various PGRs on malting barley at sites across Western Canada. In some cases, a PGR application did decrease plant height and lodging, but results were inconsistent and not significant. In general, Tidemann indicated that the inconsistent results of Manipulator suggest that the product is not suited for use on malting barley.

Information for this article was sourced from:

  1. Belchim Canada Manipulator Brochure:
  2. Tidemann et al. 2020. Effects of plant growth regulator application on the malting quality of barley. J. Sci. of Food and Agric. 100: 2082-2089.
  3. Perrott et al. 2018. Advanced agronomic practices to maximize feed barley yield, quality and standability in Alberta, Canada. I. Responses to plant density, a plant growth regulator and foliar fungicides. Agronomy Journal 110(4): 1447-1457.
  5. Thompson et al. 2018. Effect of cultivar and agronomic management on feed barley production in Alberta environments. Can. J. Plant Sci. 98(6): 1304-1320.