Growth Regulators: What Are Your Goals?
There are many turfgrass growth regulators on the market today. Each of these regulators controls the growth of different turfgrass varieties in distinct ways with varying intensity. I am frequently asked questions like “Which regulator is the best for this situation?” “What’s the best rate for this product?” “Is this regulator safe on mixed stands?” or “Will this regulator work well all season?.”
Before answering any of these questions, I always ask the client an important question. “What are your goals concerning the regulation of the particular turfgrass area in question?” The answer to that question helps determine the best strategy for growth regulators on the property.
If clipping reduction is the primary goal, a regulator containing trinexapac-ethyl, such as ArmorTech PGR 113, or prohexadione calcium, found in Anuew, would be a good choice. Both slow the upward growth of a wide variety of turfgrasses while allowing root growth to continue.
When controlling the growth of Poa annua is the primary goal, or conversion to higher populations of bentgrass, a different product will need to be used.
Paclobutrazol, the active ingredient in ArmorTech PAC 223, has a high level of activity on bentgrasses as well as annual bluegrass. Paclobutrazol used on mixed stands can be too harsh for some populations at greens height. Paclobutrazol can also be detrimental to Kentucky bluegrass and ryegrass surrounds. Continued use over time can lead to weakened or sunken areas very close to the green.
Flurprimidol, the active ingredient in Cutless MEC, will control the Poa annua growth well. It will, however, allow lateral growth of bentgrass, making it a good choice as a tool for conversion. Divots and ball marks will recover more quickly when flurprimidol is used verses paclobutrazol.
Legacy is a pre-mix combination of trinexapac-ethyl and flurprimidol. The ratio has been set to capitalize on the synergistic effects of the two actives together.
Musketeer is another pre-mix combination containing trinexapac-ethyl, flurprimidol, and paclobutrazol. The equal portions of flurprimidol and paclobutrazol provide enough active ingredients to deliver positive effects while minimizing any negative results along with just enough trinexapac-ethyl to provide clipping reduction.
Growth regulators can be an important tool for any turf manager to use throughout the growing season. The University of Nebraska-Lincoln Extension Turfgrass Specialist, Bill Kreuser, Ph.D., has developed Growing Degree Day models for each of the actives discussed above. It can be a very useful tool to help to schedule the timing of applications.
Your ATS sales rep can help you determine the best strategy to meet the goals set for your property. The time of applications, combinations of actives, and pricing of each of these products are all factors that need to be considered when deciding which to use on your property.