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What´s New in Weed Control

By Suz Trusty


With new chemistry, new modes of action and new technology, it’s an exciting time for weed science in the turf industry. Product advancements are addressing concerns specific to the timing of applications related to turf establishment and overseeding, and of extended periods for application that are better adapted to the seasons of sports field use. The focus on the “one-stop shop” concept continues, with one application targeting a range of both broadleaf and grassy weeds.

A mature crabgrass plant crowds out the desired turf.
Emerging crabgrass amidst desired turf.
Photos courtesy of Bayer Environmental Science.

New introductions

Products new to the market have undergone testing by university weed science specialists and contract researchers. For input on product performance under conditions similar to those on your fields, contact the companies for their cooperators list, or connect with your regional university turf researchers. With registration recently received on new introductions, state registrations may still be pending. Check with company representatives for updated information.

Bayer Environmental Science

Bayer Environmental Science has received registration for Specticle, a preemergent herbicide designed for use on warm-season turf. Laurence Mudge, technical service lead, said, “The mode of action varies for preemergence products. Ronstar acts on shoots only. Dinitroanilines (DNA) and dithiopyr act on roots and shoots. The active ingredient in Specticle is indaziflam, a cellulose-biosynthesis inhibitor (CBI) that acts only on the roots, terminating growth by inhibiting the development of cells within them. The use rates are up to 40 times less active ingredient than other preemergent herbicides.”

Matt Bradley, herbicide product manager, said, “On the grasses, we’re seeing comparable control on crabgrass, control superior to DNAs on goosegrass and unsurpassed Poa annua control. Rate flexibility gives turf managers a tool to match their needs; at the lower rate they’ll get three to four months of control, at the higher rates, Specticle can last eight months.”

There’s a wider window for application timing, too. Bradley said, “For Poa control, applying Specticle prior to weed emergence will provide residual control of Poa and over 60 broadleaf weeds throughout the winter. With a later application in the fall, when Poa has already started to emerge, Specticle will provide postemergent control of small Poa plants, along with the other weed coverage.”

Bradley noted that Specticle should not be applied to newly seeded, sodded or sprigged turf. The initial formulation is a 20 percent wettable powder that is odor and stain-free and causes no whitening or bleaching of existing turf. It comes in premeasured, water-soluble packets to reduce the risk of incorrect application rates and worker exposure.

FMC Professional Solutions

In September, FMC Professional Solutions announced federal registration for SquareOne, a selective, postemergent they call, “A starter herbicide for newly seeded turf.” The active ingredients are carfentrazone and quinclorac, which, in combination, work primarily through foliar contact and uptake. The label states that the product is absorbed by plant shoots, foliage and roots. In addition, according to Adam Manwarren, product manager for turf and ornamental products, following application it continues to hold back weed competition until the new turf is established. It’s available in a patent-pending formulation called Water Dispersible Granules (WDG) for ease of application.

Manwarren said, “SquareOne herbicide can be applied up to one day before seeding or as early as seven days after emergence on most cool and warm-season grasses. This reduces weed populations from the start, allowing the turf to develop without weed competition for maximum turf density, increasing the success rate for renovations, as well as new sports field installations.”

SquareOne select preemergent from FMC Professional Solutions is a starter herbicide for newly seeded turf.
Photo courtesy of FMC Professional Solutions.

SquareOne focuses on the one-stop shop concept, controlling both annual grasses and broadleaf weeds. It can be applied on actively growing cool or warm-season grasses and to dormant warm-season grasses, but not during the period when warm-season turf is transitioning out of dormancy.

Manwarren said, “SquareOne is the right fit for interseeding and overseeding in established turf, as well as new seedings. Assuming the initial application was made seven days after emergence, additional overseeding could be done one day after application.” That’s an advantage where frequent overseeding is used in heavy wear areas.

DuPont

DuPont’s newest broadleaf control product to receive EPA registration is Imprelis herbicide, with the active ingredient Aptexor, the first compound in a new chemical subclass of carboxylic acid herbicides. The nonphenoxy pyrimidine structure provides a broader spectrum of activity at lower application rates than other carboxylic acid products. Through foliage contact and strong soil activity, it’s absorbed by plant leaves and roots, stopping the growth of target weeds by interfering with the hormonal balance necessary for normal shoot and root development. It provides preemergent and/or postemergent control on a spectrum of listed broadleaf weeds, with postemergent application required for perennial weeds.

Imprelis is labeled for application on established turf of the key species of cool-season grasses most frequently used on sports fields: Kentucky bluegrass, perennial ryegrass and tall fescues. Currently, it’s only labeled for application on Bahiagrass, centipedegrass and zoysiagrass in the warm-season turfgrasses.

This untreated test plot shows the results of new seeding after seven days without the weed control of SquareOne. This test plot shows the results of SquareOne on a new seeding seven days after application.
Photos courtesy of FMC Professional Solutions.

During renovation, Imprelis can be applied immediately prior to or after seeding cool-season turfgrasses (except bentgrass), and it is rainfast immediately after application. Repeat applications may be made a minimum of 14 days after the first treatment. Seeding, sodding, sprigging or plugging with warm-season turfgrasses must be delayed at least 60 days after application of Imprelis.

PBI/Gordon

PBI/Gordon Corporation introduced two herbicide formulations in 2010. According to Doug Obermann, professional product manager for PBI/Gordon’s professional turf and ornamental products, Q4 Plus Turf Herbicide was developed to help fill the gap caused by the EPA’s decision to ban organic arsenical herbicides. Sports fields were placed in the same category as commercial and residential turf, with sales of any product containing the postemergence grassy weed control MSMA (monosodium methanearsonate) stopped on December 31, 2009, and the use of stored product for those applications banned at the end of 2010.

PBI/Gordon’s new Q4 Plus provides postemergent control of grassy and broadleaf weeds and yellow nutsedge.
Photo courtesy of PBI/Gordon Professional Turf & Ornamental Products.

Q4 Plus is a reformulation of Q4 Turf Herbicide, increasing the quinclorac from that product’s .5 pound per acre to .75 pound per acre. There was no change in the other ingredients: sulfentrazone +2,4-D + dicamba, with the new formulation continuing to provide postemergent control of grassy and broadleaf weeds and yellow nutsedge. Obermann said, “Q4 Plus increases the knockout power on grassy weeds, usually with visual results within 24 to 48 hours. It’s labeled for use on the cool-season grasses most important to sports fields, bluegrasses, perennial and annual ryegrasses and fescues and now for bermudagrasses in the warm-season turfgrasses.”

The second introduction is Trimec 1000 Low Odor Broadleaf Herbicide. It contains four active ingredients: MCPP and dicamba with two forms of 2,4-D, DEA (diethanolamine) and DMA (dimethylamine). Obermann said, “The combination of these two forms of 2,4-D is classified as a ‘mixed-amine,’ with unique control activity resulting from that combination. Trimec 1000 resists crystallization, which allows for greater absorption and the translocation of more active material into the roots, a definite advantage in controlling deep-rooted perennial weeds.”

Delay application of Trimec 1000 until after the second mowing on newly seeded areas; for Q4 Plus, wait for the second or third mowing or 28 days after emergence. Either could be applied three to four weeks following sodding, sprigging or plugging. Allow three weeks between application and reseeding or overseeding for Trimec 1000, four weeks for Q4 Plus. Both are labeled for application at temperatures up to 90 degrees. In all areas of application, if state, regional or local governments have more stringent regulations, they must be observed.

The author is a contributing editor for SportsField Management.