Tolerance of Transplanted Seashore Dropseed to Pre- and Postemergence Herbicides

Abstract

<jats:p>Field experiments were conducted to assess the tolerance of seashore dropseed (<jats:italic>Sporobolus virginicus</jats:italic>) to pre- and postemergence herbicides labeled for roadside right-of-way use. Dithiopyr (0.25 and 0.50 lb/acre a.i.), trifluralin + isoxaben (2.0 + 0.5 and 4.0 + 1.0 lb/acre a.i.), oxyfluorfen (0.25 and 0.50 lb/acre a.i.), oxadiazon (2.0 and 4.0 lb/acre a.i.), and granular table salt (99% sodium chloride, 1% sodium silicoaluminate; 83% of particles 0.5–0.25 mm in diameter, 400 lb/acre a.i.) were applied at 2 and 84 days after transplanting (DAT). Pre-emergence weed control with crop response measures as visual foliar injury ratings and aboveground biomass accumulation were recorded 38 days after the second application of herbicides (DAH2). Crop response to postemergence herbicides aminopyralid (1.10 lb/acre a.i.), triclopyr (3.0 lb/acre a.i.), a prepackaged mix of carfentrazone + (4-chloro-2-methylphenoxy)acetic acid + mecoprop + dicamba (0.02 + 1.11 + 0.22 + 0.11 lb/acre a.i.), and sulfosulfuron (0.06 lb/acre a.i.) applied at 70 and 98 DAT included visual foliar injury ratings and aboveground biomass accumulation at 28 DAH2. Although all pre-emergence herbicides (except table salt) exhibited acceptable weed control ratings, only oxadiazon and oxyfluorfen showed exceptional weed control and safety. The postemergence herbicide sulfosulfuron was the least injurious to seashore dropseed. The mixture of carfentrazone + (4-chloro-2-methylphenoxy)acetic acid + mecoprop + dicamba and triclopyr were the most injurious to seashore dropseed and should only be used as a directed spray treatment. An unintended overapplication of aminopyralid was phytotoxic, but it did not lead to complete plant death at 28 DAH2. These data identified oxadiazon, oxyfluorfen, and sulfosulfuron as safe and effective for establishing transplanted seashore dropseed plugs.</jats:p>

Pre- and Postemergence Herbicide Tolerance of Tropical Fimbry, a Native Hawaiian Sedge with Potential Use for Roadside Revegetation

“…In terms of seedhead counts, no differences were observed between the untreated and preemergence herbicide treated tropical fimbry ( Table 1). The degree of injury and stunting (based on visual vigor ratings) observed in this study are similar to other preemergence herbicide studies that were conducted in several herbaceous species (Baldos et al, 2010;Derr, 1994;Fain et al, 2006;Neal and Senesac, 1991). Oxadiazon was tolerated by container-grown grasses such as pampas grass (Cortaderia selloana) and fountain grass [Pennisetum setaceum (Neal and Senesac, 1991)] and wildflowers such as black-eyed Susan Vigor rating was based on a visual scale of 0% to 100%, where 0% = plant death and 100% = no injury and showing vigorous growth.…”

“…oadside revegetation and roadside landscaping with native species have increased over the past decade because of growing environmental awareness, recent plant material availability (Knapp and Rice, 1994), and active promotion by the Federal Highway Administration (Harper-Lore, 1996;Steinfeld et al, 2007). In Hawaii, the use of native species on roadsides is a relatively new endeavor (Baldos et al, 2010). Roadside establishment and seed production protocols are currently being developed for several native groundcovers and shrubs.…”