For busy superintendents, plant growth regulators (PGRs) are allies in the fight for efficiency. Not only do they reduce labor needs, but they also help turfgrass make the most of its limited resources through stressful conditions.
Many superintendents like using the active ingredient trinexapac-ethyl because the application rates are user-friendly and consistent. Trinexapac-ethyl is the active ingredient in PGR 113 MC, which can be used on greens, tees, fairways, and bunker slopes.
The use of PGRs around bunker slopes has gained traction recently due to labor shortages. Because string trimming is so time-consuming, you’ll free up a lot of time by controlling growth. Then you can use that time to work on other parts of the course.
PGR 113 MC is labeled for both cool-season and warm-season grasses, and the exact application rates depend on the turf type. The rate for greens and tees is usually 5–6 ounces per acre, while the fairway rate is typically 10–12 ounces per acre. As always, read the label to find the correct rate for your site.
Not all PGRs work the same way. PGR 113 MC is a foliar application that can be tank-mixed with fertilizers and fungicides. Once in the plant, it slows cell elongation, which keeps the turf at a lower height. Another major benefit is that it keeps the plant from concentrating on growth when stressed out by play, cultural practices, or weather. As a regular part of turf maintenance, it can help increase turf density and decrease water needs, giving turf the boost it needs to survive even the most challenging conditions.
Most superintendents start their PGR programs in the spring when the influx of growth starts. For best results, begin applications before extreme summer stress and continue applications bi-weekly. Then you can wrap up applications when growth slows in the fall.
Other PGR options to consider are Anuew and PAC 223. Anuew is a Nufarm PGR that contains prohexadione calcium and behaves similarly to PGR 113. It slows upward growth while allowing root growth to continue. Anuew can reduce mowing frequency on greens, tees, fairways, and roughs. PAC 223 is another PGR from ArmorTech. It contains paclobutrazol, which has a high level of activity on bentgrass and annual bluegrass. PAC 223 can be too harsh for some populations at greens height, so be careful using it on mixed stands.
Aneuw specifically has become a popular option on greens and fairways because it has lower peaks and valleys when it comes out of regulation. You don’t get that ‘spike’ with Aneuw at the end of your growing degree days or 14-day intervals like you do with trinexapac-ethyl, so I’ve had a lot of my customers switch to it. Aneuw is more expensive than PGR 113, but you’ll see more of a benefit and won’t have to spray as much, and it regulates the bentgrass a lot more as well.
Mixing Cutless MEC with Aneuw or PGR 113 regulates the bentgrass and sucks down the Poa to combat the late afternoon slowdown on greens. This is especially beneficial for courses with a large percentage of Poa. Instead of flourishing and being higher than the bentgrass at one o’clock in the afternoon, Poa often gets sucked down, slowing greens down and resulting in noticeable growth. This combination can fix that. It comes at an increased cost, but my customers have been pleased with the decrease in slowdown and the reduction in Poa over time. Keep in mind that results won’t be immediate, but with repeat applications year-over-year, you’ll see a reduction in the percentage of Poa.
There is a resistance factor using the same PGRs over and over. So, it’s healthy to switch your PGRs up, just like you would with a pesticide, to confuse the turf and get more regulation out of it.
Whether you’ve never tried PGRs before or just want to use them more effectively, your sales representative can help you tailor a PGR program that will meet your course’s specific needs.
