Research Report continued
Preemergence and Postemergence Control of Arthraxon hispidus Virginia Tech Researcher: Jeffrey F. Derr, Ph.D., Professor of Weed Science, and Adam Nichols, Research Assistant, Virginia Tech, Hampton Roads Agricultural Research and Extension Center, Virginia Beach Research Sponsors: Virginia Turfgrass Council and Virginia Turfgrass Foundation
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ointhead arthraxon [Arthraxon hispidus (Thunb.) Makino], also referred to as small carpetgrass, is a native of Asia. Jointhead arthraxon is a low-growing grass with ovate leaf blades and hairs along the margins of the leaf blades, and the cordate bases of the leaves encircle the stem. The flowers are borne on digitate spikes. This summer annual grass prefers sunny, wet habitats. It can be a weed in turfgrass and other areas. Little information is available on the control of this weed. In our research,
we conducted greenhouse trials to evaluate commonly used preemergence and postemergence herbicides in turfgrass for control of jointhead arthraxon. Pendulum (pendimethalin), Barricade (prodiamine), Tenacity (mesotrione), Ronstar (oxadiazon), Dimension (dithiopyr), Tupersan (siduron), Specticle (indaziflam) and Dacthal (DCPA) all gave 80% or greater preemergence control of jointhead arthraxon. Pylex (topramezone) and Drive (quinclorac) provided lower control.
In postemergence trials, single applications of Acclaim Extra (fenoxaprop) and Fusilade (fluazifop) and two applications of Tenacity, Pylex or MSMA all gave 70% or greater control of jointhead arthraxon. Dimension and Specticle provided overall lower postemergence control, while Drive did not control this weed when applied postemergence. Control strategies for jointhead arthraxon appear to be similar for this weed and for crabgrass, with the exception of Drive application. c
Rimsulfuron Plus Metsulfuron for Spring and Fall Transition of Overseeded Bermudagrass Turf Virginia Tech Researcher: Michael C. Cox, Graduate Research Assistant, and Shawn D. Askew, Ph.D., Associate Professor and Turfgrass Extension Specialist
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egate™ is a new herbicide developed by Quali-Pro and released in 2013 into the turf market. Negate contains the active ingredients rimsulfuron and metsulfuron to form a bermudagrass-transitioning herbicide that should offer a broader spectrum of grass and broadleaf weed control than other products currently on the market. Field trials were conducted in spring 2012 and 2013 and fall 2013 in Blacksburg, VA, at the Glade Road Research Facility to determine how Negate™ compares to industry standards for perennial ryegrass/bermudagrass transitioning and how perennial ryegrass establishment is affected from different overseeding timings after application of these herbicides. Trial locations were on ‘Patriot’ bermudagrass fairways maintained at a 0.5"
mowing height. The perennial ryegrass control studies were initiated on May 16, 2012, and May 29, 2013. The perennial ryegrass establishment study was conducted exactly like the perennial ryegrass control study with the addition of four perennial ryegrass overseeding times per herbicide treatment to assess perennial ryegrass stand establishment. Herbicide treatments for both studies included Negate at 1.5 oz./A, QP rimsulfuron at 1.0 oz./A, Monument™ (trifloxysulfuron) at 0.35 oz./ A, Revolver® (foramsulfuron) at 17 fl. oz./A and Katana™ (flazasulfuron) at 1.5 oz./A. All treatments contained a nonionic surfactant at 0.25% v/v, and an untreated check was included for comparisons. Negate controlled perennial ryegrass, annual bluegrass, common dan-
28 | Virginia Turfgrass Journal May/June 2014 www.vaturf.org
delion and white clover equivalently to or better than the industry standards QP rimsulfuron, Monument, Revolver and Katana, 35 days after treatment (DAT). All treatments reduced perennial ryegrass stand biomass by greater than 20%, 8 weeks after treatment, except Negate and QP rimsulfuron at the 28 DAT seeding and Revolver® at all seeding times. Bermudagrass was not injured at any time during these studies. These data suggest that Negate™ is an effective herbicide for controlling perennial ryegrass, annual bluegrass, common dandelion and white clover in a spring bermudagrass-transitioning situation, but they should not be applied later than approximately four weeks before overseeding with perennial ryegrass in the fall to avoid perennial ryegrass biomass reduction exceeding 20%. c