The New Herbicides

With the massive amount of new information that becomes available every year for turfgrass managers to decipher, it is difficult for anyone to keep up. New herbicides and herbicide research is no exception. And the old saying “There is more than one way to skin a cat,” applies directly to herbicides as well. With today's technologies, there is definitely more than one way to kill a weed.

The following is a review of new herbicides that have been introduced or relabeled for a new turfgrass use in 2005 or 2006. This review is not intended to eclipse the herbicide label itself, so in all cases, please consult the herbicide label directly before using any of these herbicides.

QUICKSILVER (FMC CORP.)

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QuickSilver (carfentrazone-ethyl) is a broadleaf active contact herbicide that was introduced into the turfgrass market before 2005. However, in 2005 it received a supplemental labeling in selected states for niche use in the turfgrass market: moss control in bentgrass putting greens.

Moss, often referred to as silvery-thread moss (Bryum argenteum), is an increasing problem in bentgrass putting greens. It is thought to be a result of lower mowing heights and decreased fertility to satiate our need for increased green speeds. Such stressful condition severely inhibits the ability of the turf to recover from injury and moss can easily invade.

Past research has evaluated various micronutrients, nitrogen applications, fungicides and soaps. While some control was observed with such strategies, all were inconsistent and variable under different weather conditions.

QuickSilver has been evaluated by numerous researchers and has been observed to be a very effective product for moss control. Two applications of QuickSilver at 6.4 fluid ounces per acre applied two weeks apart quickly desiccates moss with no observable injury to bentgrass turf under normal conditions.

But remember, moss probably invaded due to the low competitive ability of the bentgrass. QuickSilver will kill the moss, but you must still increase the vigor of the bentgrass. Increasing nitrogen fertility and light verticutting, during the optimal time of the year, could potentially improve overall management of moss contamination.

While QuickSilver is great on moss, it is ineffective on algae. Many turfgrass managers group moss and algae together and why not, they are both weird spore producing weeds that don't fit the description of normal weeds we deal with. Evaluations at the University of Tennessee in 2005 have demonstrated that QuickSilver definitely knows the difference between the two species.

Lastly, QuickSilver also has specific wording on the label that allows for application to newly seeded or sprigged turfgrass areas. Due to its broadleaf activity, this is an excellent treatment for small seedling broadleaf weeds across the board and allows for an earlier application compared to traditional broadleaf herbicides such as 2,4-D.

CERTAINTY (MONSANTO, REGAL)

Certainty (sulfosulfuron) is yet another herbicide in the growing list of sulfonylurea herbicides, which also includes Monument and Revolver, among others. Like Monument, it is very effective against sedge species, such as yellow nutsedge and green kyllinga. It also controls a select number of broadleaf weeds; however, this list is limited.

Unlike Revolver and Monument, Certainty is labeled for use on numerous turfgrass species other than bermudagrass and zoysiagrass. The addition of St. Augustine, centipede and kikuyu grasses adds more potential flexibility for those who deal with multiple turfgrass species on one golf course or landscapers who manage different home lawn grasses.

One unique characteristic is that Certainty can also be used to control rough-stalk bluegrass (Poa trivialis) in bentgrass turf. Rough-stalk bluegrass is the ugly cousin to annual bluegrass (Poa annua) and, due to its perennial nature, there are few herbicide options available for control, especially removal from cool-season turf. See label directions for specific recommendations.

Speaking of annual bluegrass, Certainty, while herbicidially active on annual bluegrass, provides only suppression with single applications. Small annual bluegrass plants can be controlled with Certainty, but larger plants will recover from the injury.

SURGE (PBI/GORDON)

Surge (sulfentrazone + 2,4-D + MCPP + dicamba) is a new broadleaf herbicide that contains a new herbicide to the turfgrass market, sulfentrazone. Sulfentrazone is a protox-inhibiting herbicides that induces the formation of free radicals that destroy plant tissues. Translation: It burns the plant up really fast. Sulfentrazone primarily functions as a contact herbicide with little translocation.

As you can tell by the names, sulfentrazone and carfentrazone are in the same family of herbicides. But while carfentrazone has no activity on sedges, sulfentrazone is active on both broadleaf weeds and sedges.

While sulfentrazone is active on sedge species, there are potential limitations. Research has demonstrated that sulfentrazone controls yellow nutsedge very well and controls green kyllinga comparable to standard sedge herbicides. However, as a single application, Surge has not been researched. Sedge control with Surge, therefore, would be classified more as suppressing perennial species or controlling small annuals. Despite the reduced amount of sulfentrazone in Surge compared to past research, I have heard numerous reports of satisfied customers using Surge for sedge control.

SPOTLIGHT (DOW AGROSCIENCES)

Spotlight (fluroxypyr) is a new broadleaf herbicide for use on all major turfgrass species for control of broadleaf weeds. Spotlight contains fluroxypyr, an herbicide that is primarily active against broadleaf weeds. It acts in a similar fashion to triclopyr (Turflon Ester and also contained in Confront) and other broadleaf herbicides, such as 2,4-D, by functioning as an auxin-type herbicide inducing uncontrolled cell elongation and leaf and stem twisting.

Like most herbicides that primarily target broadleaf weeds, tank-mixtures are more beneficial because they broaden your spectrum of weeds controlled. However, research conducted in Tennessee indicates that Spotlight effectively controls many broadleaf species, such as white clover (Trifolium repens), ground ivy (Glechoma hederacea), and dandelion (Taraxacum officinale), when applied at 2 pints per acre.

ESCALADE (NUFARM)

Escalade (2,4-D + fluroxypyr + dicamba) is a mixture of the new herbicide fluroxypyr pre-packaged with 2,4-D and dicamba. Such a mixture can only increase the spectrum of broadleaf weeds controlled and the activity on more difficult to control broadleaf weed species. Two applications of Escalade at 1.5 quarts per acre applied 6 weeks apart controlled Virginia buttonweed (Diodia virginiana) 100 percent compared to less than 70 percent control from two applications of a traditional three-way (2,4-D, mecoprop, dicamba) herbicide.

SEDGEHAMMER (GOWAN)

Not a new herbicide, only a new name. Formerly named Manage (Monsanto), SedgeHammer (halosulfuron) is formulated and labeled for the exact same use. If you know Manage, you know SedgeHammer. Like all SU herbicides, remember to add the appropriate surfactant.

KEEP 'EM COMING

While these are some of the new herbicides that have become available recently, there will be many more in the coming years. Unique herbicides are being developed with safer toxicological properties and new modes of action. So get ready. With new herbicides come new possibilities for weed management.

Scott McElroy is an assistant professor and extension specialist in the department of plant sciences at the University of Tennessee (Knoxville, Tenn.).

Trade Name: QuickSilver

Supplier: FMC Corp.

Chemical Name: Carfentrazone-ethyl

Use Areas: Golf course, sports field, residential and non-residential turf.

Turf Safety: All major turfgrass species

Target Weeds: Broadleaf weeds, moss

Use rates: 6.7 fluid ounces per acre for moss in putting greens, 1.1 to 2.1 fluid ounces per acre for all other areas.

Trade Name: Certainty

Suppliers: Monsanto, Regal

Chemical Name: Sulfosulfuron

Use Areas: Golf course (except greens), athletic fields, sod farms, residential and non-residential areas.

Turf Safety: Bermudagrass, St. Augustinegrass, zoysiagrass, centipedegrass, kikuyugrass, bentgrass (under certain conditions)

Target Weeds: Yellow nutsedge, green kyllinga, select broadleaf weeds, Poa trivialis

Trade Name: Spotlight

Supplier: Dow AgroSciences

Chemical Name: Fluroxypyr

Use Areas: Golf course (except tees and greens), athletic fields, sod farms, residential and non-resi- dential areas.

Turf Safety: All major turfgrass species.

Target Weeds: Broadleaf weeds

Use rates: ⅔ to 2.5 pints per acre

Trade Name: Surge

Supplier: PBI/Gordon Corp.

Chemical Name: Sulfentrazone + 2, 4-D + mecoprop + dicamba

Use Areas: Golf course (except tees and greens), athletic fields, sod farms, residential and non-resi dential areas.

Turf Safety: Majority of turfgrass species except centipedegrass and St. Augustinegrass

Target Weeds: All broadleaf weeds, yellow nutsedge

Use rates: 2.5 to 4.0 pints per acre

Trade Name: Escalade

Supplier: Nufarm

Chemical Name: 2,4-D + fluroxypyr + dicamba

Use Areas: Golf course (except tees and greens), athletic fields, sod farms, residential and non-resi dential areas.

Turf Safety: All major turfgrass species.

Target Weeds: Broadleaf weeds

Use rates: ⅔ to 3.0 pints per acre

Trade Name: SedgeHammer

Supplier: Gowan

Chemical Name: Halosulfuron

Use Areas: Golf course, athletic fields, sod farms, residential and non-residential areas.

Turf Safety: All major turfgrass species.

Target Weeds: Sedges

Use rates: 0.67 to 1.3 ounces per acre

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