COLUMBUS, Ohio – Several new herbicide active ingredients and combination products have been introduced to the market the past few years. Here’s a rundown from the Broadleaf Herbicide Trials at The Ohio State University Turfgrass Field Day attended by the Turf magazine staff.  


This is a brand new active ingredient from Dow AgroSciences. It will be marketed as Defendor and only be available in a co-pack with Dimension 2EW. Plans are for the product to become available this winter. The product can be used safely on all major turfgrasses, and should be applied at typical preemergence crabgrass timing. To prevent dandelion flowering, application should be made prior to dandelion bloom.

Weeds controlled include dandelion, white clover, common and mouse-ear chickweed, mustard and shepherd’s purse.

Research conducted at The Ohio State University shows that a single application of Defendor herbicide provides 90-plus percent control of both dandelion and clover for 84 days. On plots receiving sequential applications (42 days apart) control was still nearly 100 percent 98 days after the initial application.


Many new combination products have been formulated in an attempt to control both broadleaf weeds and grassy weeds postemergence with a single application. Some of these products also will control yellow nutsedge. Quinclorac is not new, of course, but increasingly it is appearing in combination products, not just for crabgrass control, but also for broadleaf weed control, particularly clover.

Solitare is a newer herbicide from FMC. It combines quinclorac and sulfentrazone. The result is excellent control of broadleaf weeds, sedges and crabgrass. Other products that control both crabgrass and broadleaf weeds include Quincept (2,4-D, dicamba and quinclorac), Onetime (MCPP, dicamba and quinclorac) and Q4 (2,4-D, dicamba, sulfentrazone and quinclorac).

The main use for quinclorac is, of course, for crabgrass control. In the past couple of years, new products have been introduced containing quinclorac in combination with another prodct for both pre- and postemergence control of crabgrass, such as Echelon  (quinclorac + sulfentrazone) and Calvalcade PQ (quinclorac + prodiamine, the active ingredient in Barricade). These products, along with Dimension, can be applied after crabgrass grass emerged (up to 1-2 tiller, depending on the product) to achieve season-long control.

Establishing turfgrass from seed in the spring has always been a challenge because of competing weed pressure, particularly crabgrass. However SquareOne, which combines quinclorac and carfentrazone, as well as Tenacity herbicide, can be effective particularly when establishing turfgrass from seed.

Triclopyr, clopyralid and fluroxypyr

The pyridinoxy herbicides have an important place in weed management as components of many of the newer combination herbicide products. Triclopyr is an active ingredient in several herbicides, including Turflon ester ultra, Confront, T-Zone (2,4-D, dicamba, triclopyr and sulfentrazone), 4-Speed XT (2,4-D, dicamba, triclopyr and pyraflufen-ethyl) and Cool Power (with dicamba and MCPA).

Clopyralid appears in such products as Lontrel T&O and Confront.

Fluroxypyr is an active ingredient in Escalade herbicide (with 2,4-D and dicamba).

Both clopyralid and fluroxypry have excellent activity against bird’s foot trefoil, a legume with bright yellow flowers possessing excellent drought tolerance. It’s an escaped pasture crop that’s becoming prevalent in managed turfgrass areas.

Chelated iron

Fiesta herbicide contains a proprietary chelated iron that, when applied to turf, acts as a postemergence herbicide against many broadleaf weeds. Control is very rapid with nearly 100 percent weed burn down within 24 hours.

This is a contact herbicide. Research is underway to determine if a program of sequential applications can be effective to achieve long-term weed control. Programs have included two applications in the fall, followed by two application in the spring compared to three applications in the spring at various rates and concentrations of the product.

Preliminary results at The Ohio State University suggest that when using this product to achieve long-term weed control, the total amount of Fiesta applied over a season is at least as important as the schedule of the applications.

Best results those far have been with three applications at an 8 percent solution applied at 2.5 gallons per 1,000 square feet at 21-day intervals. This has resulted in excellent control of dandelion, white clover and ground ivy. It has also resulted in good control of broadleaf plantain for up to 70 days.

Since burn down is rapid, the amount of control is actually longer than with a traditional herbicide that might take up to 28 days to achieve control.  This product is legal to use in Canada where several provinces and many cities have pesticide bans. 

About the authors: Dr. David S. Garnder (show in the image above) and E. R. Harner are with the Dept. of Horticulture and Crop Science, The Ohio State University.