TURFGRASS PRODUCERS OF TEXAS RESEARCH REPORT TITLE: Weed Control and Turfgrass Response to Herbicides.

Transcription

1 TURFGRASS PRODUCERS OF TEXAS RESEARCH REPORT-2008 TITLE: Weed Control nd Turfgrss Response to Herbicides. PROJECT LEADER: W. Jmes Grichr; Texs AgriLife Reserch; Beeville, TX Jim McAfee, Texs AgriLife Extension; Dlls, TX I. INTRODUCTION Weeds cn gretly decrese the overll qulity of turfgrss in Texs. A tremendous mount of money is spent ech yer by turf producers to control plethor of weed species. Turfgrss producers re constntly pplying herbicides to control vrious weeds found in sod including Texs pnicum (Pnicum texnum), berded sprngletop (Leptochlo fsciculris), KR Bluestem (Bothriochlo ischemum), nd other grsses or brodlef weeds. Bermudgrss, St. Augustine grss, nd zoysigrss re wrm-seson turfgrsses commonly used in home lwns, thletic fields, nd golf courses throughout the southern United Sttes. Due to the high demnd for these grsses, turf frms must produce lrge mount of qulity turfgrsses nd this requires the use of preemergence (PRE) nd postemergence (POST) herbicides to control troublesome weeds. Some of these herbicides my injure the turf nd the extent of this injury vries mong species nd vrieties within species. For sod producers, the questions tht must be sked re first, will the herbicide control the weeds in question nd secondly, nd perhps more importntly, will it do so without dversely ffecting the re-growth or re-estblishment of grss in recently hrvested field. Herbicides used in sod production must control the weed(s) in question, but must do so very selectively so s not to cuse long-term injury to the turf being produced. II. MATERIAL AND METHODS Herbicides were evluted in the summer of 2007 nd the spring/summer of 2008 t severl loctions cross south nd south-centrl Texs. Sprngletop ws evluted on Bufflogrss t Rod Frms in Whrton County, brodlef weeds (PRE) nd brodlef signlgrss (POST) ws evluted on Tifwy 419 bermudgrss t the King Rnch Turfgrss Frm ner Gonzles, nd KR bluestem ws evluted t the Texs AgriLife Reserch Sttion ner Beeville in monoculture sitution. Ech study ws replicted three times in rndomized complete block design nd rtings were tken during the evlution phse of the project. Herbicides were pplied using smll-plot CO 2 bckpck spryer clibrted to deliver 20 gl/a t 28 to 30 PSI. Ech plot ws 6 ft wide by 30 ft long with 1 to 2 ft on ech side which ws unspryed nd seprted plots. An untreted check ws included in ech study. In the sprngletop study, the initil herbicide ppliction ws mde on My 8, 2007 nd the (follow-up) 2 nd ppliction ws mde on June 7. Also, in the PRE study, the initil herbicide ppliction ws mde on Februry 14, 2008 with the 2 nd ppliction mde on My 8. III. RESULTS AND DISCUSSION

2 Sprngletop Control nd Bufflogrss Response to Postemergence Herbicides. After the initil herbicide ppliction, sprngletop control 30 dys fter tretment (DAT) ws greter thn 90% with Accent t 1.25 oz/a (Tble 1). Accent plus Acclim Extr controlled 67% sprngletop while none of the other herbicide tretments controlled greter thn 43%. When rted 39 dys fter 2 nd ppliction (69 dys fter the initil herbicide ppliction), Accent lone controlled 98% sprngletop while Accent plus Aclim Extr controlled 88% (Tble 1). None of the other herbicide tretments controlled sprngletop better thn 67%. Bufflogrss injury 30 dys fter 1 st herbicide ppliction ws gretest with Progrss (43%) while ny herbicide combintions which included Accent cused 13 to 30% turf injury (Tble 1). When rted 39 dys fter 2 nd herbicide ppliction (69 dys fter the initil herbicide ppliction), Progrss cused 92% injury. Accent lone cused 20% injury while MSMA lone t 2.65 nd 4.0 pt/a cused 20 nd 37% turf injury, respectively. Any combintions which included Accent cused 15 to 77% injury. The combintion of Accent plus MSMA cused the gretest injury (77%). Tble 1. Sprngletop control nd Bufflogrss injury fter postemergence herbicide pplictions. % Control % Bufflogrss injury Herbicide b Rte/A 30 DAT c 69 DAT d 30 DAT 69 DAT Untreted Asulm 5.0 pt Ktn 3.0 oz Progrss 4.0 qt Acclim Extr 20.0 oz Acclim Extr 25.0 oz Accent 1.25 oz MSMA 2.65 pt MSMA 4.0 pt Acclim 25.0 oz Extr+MSMA 4.0 pt Accent oz Acclim Extr 25.0 oz Accent oz MSMA Accent + Acclim Extr + MSMA 4.0 pt 1.25 oz oz pt LSD (0.05) Two pplictions of ech herbicide, pproximtely 30 dy prt. b All herbicide tretments included Induce t 0.25% v/v. c 30 DAT, 30 dys fter initil herbicide tretment. d 69 DAT, 39 dys fter 2 nd herbicide ppliction or 69 dys fter initil herbicide tretment. 2

3 K.R. Bluestem Control Using Postemergence Herbicides. Under monoculture sitution, without ny other grsses, glyphoste provided excellent control of bluestem when rted 27 nd 62 DAT (Tble 2). However, none of the other herbicides provided cceptble control when rted 62 DAT. MSMA provided cceptble control when rted 27 DAT but control ws less thn 40% t the other rting dtes. When rted 146 DAT, none of the herbicides provided effective KR bluestem control. These herbicides do not hve ny residul ctivity nd due to the high KR bluestem weed reservoir in the soil, long time bluestem control ws not possible. Tble 2. Control of K R Bluestem with selected postemergence herbicides. % Control Herbicide Rte/A 27 DAT b 62 DAT 146 DAT MSMA c 2.65 pt Glyphoste d 3.0 pt MSMA + Revolver 2.65 pt oz Acclim Extr 20.0 oz Accent 0.83 oz Accent 1.25 oz Accent + Acclim Extr 1.25 oz oz Accent + Acclim Extr oz + 20 oz MSMA 2.65 pt Untreted LSD (0.05) All herbicides included Induce dded t 0.25% v/v. b DAT, dys fter tretment. c MSMA pplied twice, pproximtely 4 wk prt. d Formulted s Durngo (5.4 E). Brodlef Weed Control nd Bermudgrss Response to Preemergence Herbicides. Weed pressure ws light due to lck of rinfll nd irrigtion t the Gonzles County loction. Atrzine t both rtes, Monument, Ktn, nd Sencor t both rtes controlled brodlef weeds t lest 92% when rted 46 DAT (Tble 3). Only Kerb t 3.0 lb/a filed to control weeds t lest 70%. When rted 128 DAT (40 dy fter 2 nd tretment), Monument provided complete control while ll other herbicide tretments with the exception of Kerb t 3.0 lb/a nd Pennnt Mgnum t 1.0 pt/a controlled brodlef weeds t lest 83%. Tifwy 419 lef burn ws gretest with Sencor t 16 oz/a nd both rtes of Ronstr. No stunting with the higher rtes of Pennnt Mgnum ws noted during the growing seson. This ws probbly due to lck of rinfll nd/or irrigtion within resonble time fter herbicide ppliction. 3

4 Tble 3. Weed control nd Tifwy 419 response to preemergence herbicides. Control Injury b Herbicide Rte/A 46 DAT 128 DAT 13 DAT % Untreted Pendilum 4.0 pt Brricde 1.0 lb Brricde 2.0 lb Surfln 2.0 qt Surfln 4.0 qt Kerb 1.5 lb Kerb 3.0 lb Princep 1.0 qt Princep 2.0 qt Atrzine 1.0 qt Atrzine 2.0 qt Pennnt Mgnum 1.0 pt Pennnt Mgnum 1.5 pt Pennnt Mgnum 2.0 pt Monument 0.56oz Ktn 3.0 oz Sencor 10.8 oz Sencor 16.0 oz Dimension 1.0 pt Dimension 2.0 pt Ronstr 3.0 lb Ronstr 6.0 lb Dismiss 4.0 oz Dismiss 6.0 oz LSD (0.05) Weeds consisted of burr clover nd other winter brodlef weeds. Weed control rtings tken 46 dys fter herbicide ppliction. b Bermudgrss injury consisted of lef burn. Rtings tken 13 dys fter herbicide ppliction. Brodlef Signlgrss Control nd Bermudgrss Response to Postemergence Herbicides. Under hevy brodlef signlgrss pressure, MSMA + Drive nd Monument + Accent provided t lest 89% control t both rtings. Asulm nd Accent lone controlled brodlef signlgrss 95 nd 85%, respectively, when rted 26 dys fter tretment (DAT) while control ws less thn 80% when rted 47 DAT (Tble 4). Acclim Extr controlled 52% brodlef signlgrss 26 DAT nd 75% brodlef signlgrss 47 DAT. MSMA + Sencor controlled 67 to 72% signlgrss t both rtings. No other herbicides provided better thn 50% control. 4

5 Tifwy 419 bermudgrss injury (lef yellowing or burn) ws gretest with Progrss, Acclim Extr, MSMA + Sencor, nd Drive + Sencor. Tble 4. Brodlef signlgrss control nd Tifwy 419 response to postemergence herbicides. Injury b Control Herbicide Rte/A 12 DAT c 26 DAT 47 DAT % Untreted MSMA 2.65 pt Asulm 5.0 pt Drive 1.35 lb Monument 0.56 oz Revolver 26.2 oz Ktn 3.0 oz Certinty 2.0 oz Imge 11.4 oz Mnor 0.5 oz Progrss 4.0 qt Acclim Extr 20.0 oz Accent 1.25 oz Dismiss 4.0 oz Dismiss 6.0 oz MSMA + Imge 2.65 pt oz MSMA + Sencor 2.65 pt oz MSMA + Drive 2.65 pt lb MSMA + Monument 2.65 pt oz MSMA + Revolver 2.65 pt oz Revolver + Sencor 26.2 oz oz Revolver + Imge 26.2 oz oz Imge + Mnor 11.4 oz oz Revolver + Atrzine 26.2 oz pt Drive + Sencor 1.35 lb oz Sencor 10.8 oz Monument + Accent 0.56 oz oz LSD (0.05) All herbicides included Induce dded t 0.25% v/v. b Injury consisted of lef yellowing nd burn. c DAT, dys fter herbicide tretment. 5

6 In summry, severl PRE nd POST herbicides controlled problem weeds in turf. Sprngletop ws effectively controlled with Accent but effective control requires tht the grower continuously ttck sprngletop or this weed will become n issue gin fter initil control. However, Accent is presently not clered for use in turf production. KR Bluestem control ws excellent with glyphoste; however, under most conditions the lck of selectivity with glyphoste would prevent its use. Accent, Asulm, MSMA + Drive, nd Monument + Accent provided good to excellent control of brodlef signlgrss. We would like to tke this opportunity to thnk Turfgrss Producers of Texs for their support of our reserch project. Also, the coopertors in this project, Rod Frms (Glen Rod, mnger) nd King Rnch Turfgrss (Jy Pyssen, mnger) for their time nd effort in these studies nd lso to A. J. Jks, Kevin Brewer, Bill Klesel, nd Dwyne Drozd for their help in herbicide ppliction nd evlutions. 6