New Herbicides for Weed Control in Turf
Extension Turf Weed Scientist, University of Georgia
The introduction of new turf herbicides will continue to enable practitioners to control troublesome weeds. In 2010, turf managers will see several new options for weed control from novel active ingredients, combination products, and label amendments. The following contains an unbiased view on these products and discusses efficacy for turfgrass weed control.
Celsius (thiencarbazone + iodosulfuron + dicamba)
Celsius (68 WDG) is a new combination product for postemergence weed control from Bayer. Thiencarbazone and iodosulfuron are two new active ingredients in turf while dicamba is an older chemistry used for broadleaf weed control. Celsius is intended for commercial use by licensed applicators on residential lawns, golf courses, sports fields, parks, sod farms, and other turf areas. Celsius will be labeled at 2.5 to 7.4 oz of product per acre for use in common and hybrid bermudagrass, buffalograss, centipedegrass, St. Augustinegrass, and zoysiagrass with activity on numerous annual and perennial broadleaf weeds.
Celsius has several promising aspects that practitioners will find beneficial in weed management programs. Herbicide selection for southern lawns with mixed turf species, such as centipedegrass and St. Augustinegrass, has been limited due to differential species tolerance to herbicides. Celsius will be applicable in mixed lawns containing labeled turfgrass species. However, bahiagrass and seashore paspalum are sensitive to applications and Celsius will not be applicable if these grasses are considered desirable species. This activity on Paspalum species may have potential to control or suppress several troublesome weeds.
For example, Celsius has shown to effectively control bull paspalum and in limited testing suppressed dallisgrass. Although registered rates will probably not control mature populations, Celsius may have potential for use in programs with other herbicides, such as formasulfuron (Revolver), for sequential applications to replace MSMA in dallisgrass control regimes.
Preliminary university experiments with Celsius have also shown activity for crabgrass control. However, this activity appears to be limited to young populations of large crabgrass only. Other crabgrass species, such as blanket crabgrass, have shown erratic control from Celsius and further research is needed to investigate efficacy and application regimes. New herbicides, like Celsius, with activity on grassy weeds will be significant for use in St. Augustinegrass and centipedegrass lawns due to limited products safe for use at rates required for weed control.
Katana is a new sulfonylurea herbicide from PBI Gordon that will be available in March 2010 for use in bermudagrass, centipedegrass, and zoysiagrass. Katana contains a new active ingredient, flazasulfuron, and will be formulated in a 25% dry flowable formulation. Katana has postemergence activity on numerous broadleaf and grassy weeds including clovers, dandelion, common chickweed, perennial ryegrass, annual bluegrass, and tall fescue. Katana efficacy on perennial ryegrass will aid in transition of overseeded bermudagrass in the spring and control ryegrass “clumps” in undesirable locations. In Georgia, Katana has shown excellent perennial ryegrass control (90% or greater) in spring with rates greater than 1 oz of product per acre but efficacy is generally less significant on annual bluegrass. Applying granular urea fertilizer at 1.5 lb per 1000 sq ft before Katana applications has shown to significantly improve activity on both species, compared to Katana alone, and may shorten transition time back to bermudagrass.
Katana also controls annual sedges, yellow nutsedge, purple nutsedge, and several Kyllinga species. In preliminary experiments, repeat applications of 0.5 oz of product per acre completely controlled purple nutsedge and perennial Kyllinga, similar to halosulfuron (SedgeHammer). Katana will likely have similar turf species limitations and uses in weed control programs similar to trifloxysulfuron (Monument) but with greater spectrum of broadleaf weeds controlled.
Tower is a new preemergence herbicide released in 2009 by BASF for use on golf courses. Tower is a 6L formulation and contains dimethenamid-P, a new active ingredient for turfgrass. Tower is labeled for major cool-season and warm-season turfgrass species and may be applied to golf course fairways, tees, and roughs. Preemergence Tower applications effectively control annual sedges, annual Kyllinga, goosegrass, and selected broadleaf weeds. Tower also has activity for preemergence yellow nutsedge control but is not effective against purple nutsedge. A major limitation to Tower is the activity on crabgrass. However, Tower may be used with other preemergence herbicides, such as pendimethalin (Pendulum) to improve efficacy when targeting crabgrass and other annual weeds.
Currently, Tower is labeled for golf courses only but future label amendments will likely add other turf areas. At this time (January 2010), Tower is not labeled for residential turfgrass, lawns, recreational turfgrass, sod farms, or any other turfgrass areas besides golf courses. Field research is currently being conducted at the University of Georgia to evaluate the use of Tower during turfgrass establishment. These trials are investigating reseeding intervals for perennial ryegrass and the effects of rate, formulation, and application timing on ultradwarf bermudagrass and seashore paspalum putting greens.
T-Zone (triclopyr + sulfentrazone + 2,4-D + dicamba)
T-Zone is a new combination herbicide from PBI Gordon for postemergence broadleaf weed control. T-Zone contains triclopyr, sulfentrazone, 2,4-D, and dicamba at 0.5, 0.06, 1.75, and 0.2 lb/gallon, respectively. T-Zone is labeled at 3.25 to 4 pints per acre for broadcast applications to bluegrasses, ryegrasses, and fescues. Bermudagrass, bahiagrass, and zoysiagrass may be treated during full dormancy at 2 to 2.25 pints per acre. Dormant applications to warm-season turfgrasses are recommended due to the presence of triclopyr in this product.
T-Zone has activity on numerous broadleaf weeds and may be used for residential turf, sod farms, golf courses, sports facilities, non-croplands, and other institutional sites. For golf courses, T-Zone may be applied to fairways and roughs only. Avoid applications when temperatures exceed 85° or to actively growing warm-season turfgrasses. For best results, do not mow two days before or after applications and wait until after the second or third mowing to use on newly seeded turf.
New Quinclorac Combination Products
Quinclorac is a unique herbicide for grassy and broadleaf weed control that has been used for several years in turf as Drive 75 DF. Drive XLR8 is a new liquid formulation with 1.5 pounds of quinclorac per gallon. Both Drive formulations effectively control crabgrass, foxtail, clovers, torpedograss, and other broadleaf weeds in certain warm and cool-season turfgrasses. Since quinclorac is compatible in tank-mixtures with growth regulator herbicides, combination products containing quinclorac and other active ingredients have been recently released for use in turf.
One Time contains quinclorac, dicamba, and MCPP and provides a better spectrum of broadleaf weeds controlled than Drive alone. One Time applications at 64 fl oz per acre will deliver 0.75 lb a.i. per acre of quinclorac, which is needed to provide a standard rate of Drive for crabgrass control. However, lower use rates of One Time for sensitive species, such as creeping bentgrass, will generally not deliver enough quinclorac for effective grassy weed control. Solitaire (quinclorac + sulfentrazone), Q4 (quinclorac + sulfentrazone + 2,4-D + dicamba), and Quincept (quinclorac + 2,4-D + dicamba) are relatively new combination herbicides that may provide excellent broadleaf weed control with activity on grassy weeds. However, these products may lack sufficient concentrations of sulfentrazone or quinclorac for controlling sedges and crabgrass, respectively, at rates safe for use in cool-season grasses. Always read product labels carefully before making applications to understand the limitations of combination products on specific weeds. Turf managers may wish to add more herbicides, such as sulfentrazone (Dismiss), if components are lacking in prepackaged mixture herbicides.
Label Amendments for 2010
Syngenta has received approval for label amendments for Tenacity (mesotrione) in 2010. The label amendment will permit future Tenacity use on golf courses, sod farms, athletic fields, parks, commercial areas, cemeteries, airports, and lawns. Buffalograss will also be added to the Tenacity label as a tolerant turf species at 5 to 8 fl oz/acre. Another label amendment will include Tenacity applications to dormant bermudagrass at 5 fl oz/acre for winter weed control. Monument (trifloxysulfuron) has also received a label amendment for use on residential turf and athletic fields.
Label amendments for new or old products may continue throughout the year. It is important for turf managers to read and follow label directions for all pesticides to understand new uses, new formulations, or potential restrictions of these products. Subscribers to “Turfgrass Management”, the smart phone application released by the University of Georgia, will have up to date label changes on the program when amendments are released. Other label changes during the year will be published in the 2011 pest control handbook.
Note on Products Mentioned
Listing of pesticides and other chemicals implies no product endorsement by the University of Georgia or its representatives. Omission and criticism of products not mentioned is neither implied nor intended. The University of Georgia does not accept any responsibility for omissions, errors or future amendments. Always observe directions, restrictions, and precautions on product labels.
Please share this information with others in the landscape & turf industry. For more information:
Call your local Extension Agent at (800) ASK-UGA1 or locate your local Extension Office at http://www.caes.uga.edu/extension/statewide.cfm
Pest Management Handbook (Follow all label recommendations when using any pesticide) - www.ent.uga.edu/pmh/
For more Landscape Alerts please visit the Georgia Center for Urban Agriculture