Combination products continue to be the future of turf herbicides.

When it comes to turf herbicide product selection, lawn care applicators have noticed some changes—and it’s not just limited to lack of new active ingredients.

There have been fewer products coming to the market in the past five to 10 years, says Rodney St. John, Ph.D., agronomist for Ryan Lawn & Tree. The $27-million company, located in Overland Park, Kan., provides lawn care, seeding, tree and shrub care, irrigation and perimeter pest control for predominantly residential clients.

“There has not been a new mode of action introduced into the lawn care market since HPPD inhibitors (4-Hydroxyphenylpyruvate dioxygenase) were introduced about seven years ago,” says Dean Mosdell, Ph.D., field technical manager, Syngenta Turf & Landscape. Still, Mosdell says there are new products introduced to the turf market from agriculture with older modes of action, and there are more combinations of active ingredients to fill weed control gaps.

Turf trends

The herbicide market has slowed down in the past few years in part because of the damage caused by DuPont’s Imprelis herbicide, experts say. First used in fall 2010, Imprelis—with the active ingredient aminocyclopyrachlor—was taken off the market in August 2011 when the Environmental Protection Agency (EPA) issued a stop-sale order. The herbicide caused injury to some species of trees, including Norway spruces and white pines.

While manufacturers aren’t releasing as many new active ingredients, there have been other trends catching professionals’
attention.

“Combinations have been the biggest trend, and current developments have been all postemergent,” says Ken Hutto, FMC Corp.’s technical services manager for herbicides and fungicides.

These combinations are taking the place of releasing new molecules, says Dan Loughner, product technology specialist, Dow AgroSciences. “Companies are taking product-specific herbicides to combine with other herbicides to broaden the spectrum,” Loughner says. “They’re trying to cover as many of the important weeds as possible with these combinations.”

One driving force for these trends is the loss of monosodium methyl arsenate (MSMA) for residential and commercial properties. “Many combination products were introduced to address the need for postemergent grass control after the loss of MSMA,” Mosdell says.

The focus on postemergent combinations can be traced back to agriculture. “It has to do with the molecules that are being discovered from the crop side of the business,” Mosdell adds. “There’s also a lot more regulatory hurdles from the EPA, and it’s becoming more expensive to introduce new molecules into the market.”

Product releases

With MSMA off the market, Tommy Cowett, agronomist at GrowinGreen, has been testing different herbicides on his properties. The company, located in Kernersville, N.C., has $2.2 million in annual revenue with 19 full-time employees. It serves residential, commercial and athletic field clients with lawn care, tree and shrub, aquatic weed control and vegetation management services.

New products Cowett is excited about are Tenacity from Syngenta, Last Call from Nufarm and Pylex from BASF Corp. Cowett also uses Holganix in conjunction with herbicides to get better control, he says.

“Most new products seem to focus on specific and difficult-to-control weeds or combine postemergent mono and dicot herbicides as a convenience to the applicator,” Mosdell says.

More contractors also are beginning to use low-volume, ride-on spreaders to apply herbicides, Hutto adds.

“The biggest thing with those systems is making sure you’re getting adequate coverage because those machines and ride-ons put out such low volumes, depending on the active ingredients,” he says.

Wish lists

There are still some weeds giving operators a difficult time, and the pros say they would like manufacturers to come out with new formulas to help treat them.

“I’d like to have greater tools to remove warm-season grasses from cool-season grasses,” St. John says.

On Cowett’s wish list are herbicides that selectively take roughstalk bluegrass and dallisgrass out of fescue. “Those are two perennial weeds that can really make a lawn unsightly and hard to maintain,” he says.

These difficult-to-control weeds are also on manufacturers’ minds. In fact, Hutto says there’s a focus on combining three modes of action to control dallisgrass.

At least in the short term, it appears there will be a continuation of combining active ingredients to meet weed-control needs, Mosdell says. “We have not found a complete solution for the loss of MSMA, such as dallisgrass control in cool-season turf,” he says,  adding he isn’t aware of any new herbicide active ingredients that will come out in the next two to three years for the lawn care industry.

Resistance watchers

Going forward, herbicide resistance is also something contractors and manufacturers are going to have to address.

“In the future, landscape contractors will have to deal with some resistance issues, like what we’ve seen on golf courses,” says Clint Waltz, Ph.D., turfgrass extension specialist at the University of Georgia. “They’ve used so many herbicides like triazine because they’re less expensive. But, they’ve built up cross-resistance issues. So, they might have to deal with weeds they might not be able to control any more. Resistance and cross resistance are going to be the next big issues the landscape industry is going to have to deal with.”

To help with such issues, Hutto encourages applicators to rotate their modes of action.

“One benefit of multiple active ingredients is it could be a good resistance-management tool, instead of having one mode of action attacking the weed,” he says.

Loughner says manufacturers also must consider turf tolerance when working on creating new formulas. “The grass has to have tolerance to those herbicides or it won’t work,” he says. “Turf tolerance is just as important as weed control when it comes to introducing new molecules in this market.”

Dowdle is an Alabama-based freelance writer.