Let’s talk about plant growth regulators

Spray away Experts say the benefits of PGRs come after multiple applications, not just one. (Photo: Syngenta)

Plant growth regulators’ (PGRs) benefits stem beyond the ability to control plant growth.

“On top of promoting lateral growth, helping to prevent scalping and reducing clipping yields, plant growth regulators can reduce mowing — and the labor and resources it takes to conduct that mowing,” says Eric Steffensen, eastern commercial sales manager at Arborjet. “That labor can then be deployed somewhere else on the property.”

Dean Mosdell, technical services manager at Syngenta, says PGRs are underutilized among landscape professionals.

“Lawn care operators look at the cost of the application, and since it doesn’t control a pest or disease, they may find it tough to justify, but the long-term benefits of labor and green waste reduction do have value in a lawn care market,” he says.

Landscape Management got the scoop from Steffensen and Mosdell on best practices for using PGRs.

How they work

PGRs generally inhibit shoot growth, according to Steffensen.

Photo: Arborjet

“If the energy inside a plant can’t go toward shoot growth, it redirects elsewhere,” he says. “Roots get hardier. Cuticles get thicker. The space between nodes on a branch become smaller. Carb stores become larger. Effects vary from species to species, but generally, the plant gets hardier, which means you have less problem with disease.”

Mosdell adds that turf treated with PGRs often has a healthier color than turf not treated.

Tips and tricks

Apply PGRs on a regular schedule based on label recommendations. “You can’t just apply it once,” Mosdell says. “You have to apply them on a regular schedule to see the full benefits of plant growth regulators. Don’t just put it out once and expect miracles. You can’t stretch it beyond four weeks and expect it to reap the benefits of a PGR program.”

Consider using PGRs on trees and shrubs instead of just on turf. “Traditionally, landscape professionals have balked at PGRs in this context because, if you trim a massive hedge using a team of four guys, a PGR application may cost more than paying those four guys to do that pruning,” Steffensen says. “But here’s the thing: That plant growth regulator allows professionals to skip a month or two (or three) of subsequent hedge trimming. That frees up those four guys to do something else, something more profitable and productive than trimming back shrubs.”

Consider the timing. “Turf has to be actively growing when you apply PGRs,” Mosdell says. “It’s best to maintain turf that’s irrigated, turf that won’t go dormant during the summer due to lack of irrigation. The faster the turf is growing, the more clippings it’s going to produce as you mow.”

Use PGRs strategically to save on labor. “Think about all the hours of labor you’ll be saving (using PGRs), then think about all the other productive, profitable things your guys can be doing for your customers when that problem has been mitigated chemically,” Steffensen says.