English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Research was conducted at multiple locations throughout the southeastern United States during 2012 and 2013 to assist turf managers in developing integrated programs for managing crabgrass in common bermudagrass turf. Our objective was to determine the effect of mowing height on the efficacy of several pre-emergent (PRE) herbicides labeled for crabgrass control in bermudagrass turf. Plots were established in Raleigh, NC (NCSU), Knoxville, TN (ETREC), andWinder, GA (UGA) and treated with a factorial combination of two mowing heights (1.5 or 3.8 cm), two application regimes [single or split application (initial and an 8-week sequential)], and six preemergent herbicides (dithiopyr, indaziflam, oxadiazon, pendimethalin, prodiamine, and prodiamine + sulfentrazone). In 2012, all herbicides provided greater crabgrass control on plots maintained at 3.8 cm compared with 1.5 cm. This response was not detected in 2013, potentially as a result of above-average rainfall at two of the three trial locations. Analysis revealed mowing height did not affect pendimethalin soil residue, whereas prodiamine concentrations from bermudagrass maintained at 1.5 cm were greater than bermudagrass maintained at 3.8 cm. Therefore, differences in crabgrass control in bermudagrass maintained under different mowing heights may be the result of plant growth, reduced photosynthetically active radiation (PAR) at the soil surface, among other reasons, and not solely differential degradation of applied herbicides at the 1.5and 3.8-cm mowing heights. Future research should explore effects of increasing bermudagrass mowing height on PAR required for crabgrass germination and growth. Crabgrass (Digitaria spp.) is a common weed of warmand cool-season turfgrasses. A survey of the southern United States conducted by Webster (2000) ranked crabgrass as the most common turfgrass weed in 10 of 12 southern states. Compared with desirable turfgrass species such as bermudagrass (Cynodon spp.) or tall fescue (Lolium arundinaceum Schreb.), the light green color and coarse texture of crabgrass foliage can reduce overall turf quality (Hall et al., 1994). PRE herbicides such as dithiopyr, indaziflam, oxadiazon, prodiamine, and pendimethalin are labeled for selective control of smooth crabgrass (Digitaria ischaemum Schreb.) and large crabgrass [Digitaria sanguinalis (L.) Scop.] in turf (Anonymous, 2012a, 2012b, 2012c, 2007, 2009). Previous research has reported reductions in crabgrass cover by increasing turf mowing height. Specifically, Dernoeden et al. (1993) reported 3% smooth crabgrass cover in non-treated tall fescue mowed at 8.8 cm compared with 40% and 80% smooth crabgrass cover in plots mowed at 5.5 and 3.2 cm, respectively, at the conclusion of a 3-year study. Reductions in smooth crabgrass cover with increased mowing height have been observed in other cool-season turfgrass species, including kentucky bluegrass (Poa pratensis L.), tall fescue, perennial ryegrass (Lolium perenne L.), and several fine fescue species (Festuca spp.) (Debels et al., 2012; Dernoeden et al., 1998; Dunn et al., 1981; Jagschitz and Ebdon, 1985; Voigt et al., 2001). To date, minimal information has been published regarding effects of mowing height on crabgrass cover in warm-season turfgrass species such as common bermudagrass (Cynodon dactylonL.) (Callahan, 1978; Hoyle et al., 2014). Integrated pest management has been defined as the thoughtful combination of multiple approaches such as synthetic chemical applications and cultural practices to control pests (Busey, 2003). Although the efficacy of PRE herbicides for crabgrass control and effects of mowing height on crabgrass incidence have been studied, research exploring the integration of these two practices is limited. Dernoeden et al. (1993) monitored smooth crabgrass cover after applications of dithiopyr and pendimethalin to tall fescue turf maintained at 8.8, 5.5, and 3.2 cm. Herbicide rates were reduced by 50% at the end of the 3-year study and plots mowed at 5.5 and 8.8 cm did not require a herbicide in the final year of the experiment. Smooth crabgrass cover in dithiopyror pendimethalin-treated plots was similar (3% or less) during the first 2 years of the study, regardless of mowing height. However, in the third year, smooth crabgrass cover was greater in tall fescue turf mowed at 3.2 and 5.5 cm than 8.8 cm after pendimethalin or dithiopyr application. The researchers concluded that annual dithiopyr or pendimethalin applications at labeled rates would be required when mowing tall fescue at 3.2 and 5.5 cm. However, reduced rates and less frequent applications of these herbicides could provide acceptable turf quality when mowing height was increased to 8.8 cm. Changes in common bermudagrass mowing height may affect the efficacy of PRE herbicides labeled for crabgrass control. However, minimal data have been published regarding integrated programs for managing crabgrass infestations using PRE herbicides in combination with mowing height adjustment. Therefore, the objective of this research was to determine the effect of mowing height on the efficacy of several PRE herbicides labeled for crabgrass control in common bermudagrass turf. Materials and Methods Field study. Field research to evaluate select PRE herbicides labeled for crabgrass control in common bermudagrass turf managed under different mowing heights was conducted at the East Tennessee Research and Education Center–Plant Sciences Unit (ETREC) in Knoxville, TN (lat. 35.54 N, long. 83.57 W) during 2012 and 2013. This experiment was repeated in 2013 at North Carolina State University Turf Field Laboratory (NCSU) in Raleigh, NC (lat. 35.73 N, long. 78.67 W) and Pine Hills Golf Club (UGA) in Winder, GA (lat. 33.97 N, long. 83.69 W) to evaluate treatment response across a wider geographic region of the southeastern United States. At all locations, research was conducted on established common bermudagrass. At NCSU and ETREC, plots (1 · 2.5 m and 1.5 · 2.4 m, respectively) were established in areas with a history of smooth crabgrass incidence, whereas large crabgrass was the predominant species at Received for publication 15 July 2014. Accepted for publication 17 Oct. 2014. To whom reprint requests should be addressed; e-mail travis_gannon@ncsu.edu. 546 HORTSCIENCE VOL. 50(4) APRIL 2015 UGA (1.5 · 3-m plots). Soil type at NCSU was a Cecil sandy clay loam (fine, kaolinitic, thermic typic Kanhapludult), measuring 6.4 in soil pH and 1.9% in organic matter. Soil type at ETREC was a Sequatchie loam soil (fine-loamy, siliceous, semiactive, thermic humic Hapludult), measuring 6.2 in soil pH and 2.1% in organic matter. At the UGA location, soil was a Madison sandy clay loam (fine, kaolinitic, thermic typic Kanhapludult) with a pH of 5.1 and 0.7% organic matter. In both years, turf at ETREC received two fertilizer applications at 49 kg nitrogen (N)/ ha in spring (March, April) from a complete fertilizer (21.0N–0.4P2O5–13.3K2O; Harrell’s LLC, Charlotte, NC). Supplemental nutrition was applied similarly at NCSU with two applications (April, June) made at 49 kg N/ha from a complete fertilizer (25.0N– 2.6P2O5–10.0K2O; Harrell’s LLC). Fertilizer (16.0N–1.7P2O5–6.6K2O; Griggs Brothers, Albion, ID) was applied at UGA at a rate of 49 kg N/ha in April and June. To prevent wilt, overhead irrigation was applied to supplement rainfall at each location. Additionally, plots at all locations received 0.5 cm of irrigation within 24 h of herbicide or fertilizer applications. Treatments included a factorial combination of two mowing heights (1.5 or 3.8 cm), two application regimes (single or split applications with split treatments applied at initial application and 8 weeks later), and six PRE herbicides including: dithiopyr (Dimension; Dow AgroSciences, Indianapolis, IN), indaziflam (Specticle; Bayer Environmental Sciences, Research Triangle Park, NC), oxadiazon (Ronstar; Bayer Environmental Sciences), pendimethalin (Pendulum AquaCap; BASF Corporation, Research Triangle Park, NC), prodiamine (Barricade; Syngenta Professional Products, Greensboro, NC), and prodiamine + sulfentrazone (Echelon; FMC Corporation, Philadelphia, PA). Herbicide application rates and dates are presented in Tables 1 and 2. All herbicides except oxadiazon used water as the carrier and were applied with CO2-powered backpack sprayers at all locations. Carrier volumes at ETREC, NSCU, and UGA were 280, 304, and 280 L·ha, respectively, using flatfan nozzles (XR8002; TeeJet Technologies, Wheaton, IL). A granular formulation of oxadiazon was applied at all locations with a shaker jar. Plots were mowed at 1.5 or 3.8 cm at all locations beginning 4 weeks before herbicide treatment. Plots maintained at 1.5 cm were mowed three times per week, whereas those maintained at 3.8 cm were mowed two times per week. In all cases, clippings were returned. ETREC maintained 1.5-cm and 3.8-cm plots with reel (Jacobsen LF 3800; Jacobsen, A Textron Company, Charlotte, NC) and rotary (Gravely Zero Turn; An Ariens Company, Brillion, WI) mowers, respectively. Rotary mowers were used to maintain both 1.5-cm (Honda HRC 215; American Honda Motor Company, Duluth, GA) and 3.8-cm (John Deere 997 Zero-Turn; Deere and Company, Moline, IL) plots at NCSU. Plots at UGA were maintained at 1.5 cm with a reel mower (Toro Reelmaster 5500-D; The Toro Company, Bloomington, MN) and 3.8 cm with a rotary mower (Toro Groundsmaster 3320; The Toro Company). Nontreated plots were also included for each mowing height. Crabgrass control was visually evaluated on a 0% (no control) to 100% (complete control) scale 12, 16, 20, and 24 weeks after initial treatment (WAIT) in 2012 and 2013. Crabgrass plant counts were also taken 24 WAIT in 2013 using a 1-m grid (10 cm · 10 cm spacing) placed in the center of each plot. All count data are expressed as a percent reduction compared with the non-treated control at each respective mowing height. The experimental design was a randomized comple

Preemergence Herbicide Efficacy for Crabgrass (Digitaria spp.) Control in Common Bermudagrass Managed under Different Mowing Heights