Vol. 54â2000 - NorthEastern Weed Science Society
Vol. 54â2000 - NorthEastern Weed Science Society Vol. 54â2000 - NorthEastern Weed Science Society
EFFECTIVENESS OF GLYPHOSATE AND SEVERAL OTHER HERBICIDES FOR MANAGING WEEDS IN ROUNDUP READY CORN D. G. Voight, W. S. Curran, R. L. Hockensmith, G. J. Hostetter, J. M. Hunter, D. D. Lingenfelter, D. T. Messersmith, and J. E. Rowehl' ABSTRACT With the recent introduction of Roundup Ready com (Zea mays L.) hybrids, some speculation bas been placed on herbicide mixtures with glyphosate and application timing to obtaineffectiveweedcontrol. Thefollowingresearchwas designedto evaluateglyphosatealone atdifferentapplicationtimingsas well as to compareglyphosatemixedwith otherherbicidesto traditionalherbicideprograms. In 1999, field studies wereconducted at Lawrence, Crawford, Juniata, York, Lebanon, and Wayne counties Pennsylvania. Roundup Ready com wasplanted during May and the following herbicide treatments were evaluated: (1) s-metolachlortatrazine plus pendimetbalin, PRE (2.2lb and 1.24lb aiJA respectively); (2) acetochlortatrazine, PRE (2.8Ib aiJA) followed by glyphosate, POST, (lib aiJA); (3) glyphosate, EPOST, (lib/A); (4) glyphosate, POST, (I Ib/A); (5) glyphosate, LPOST, (lib/A); (6) glyphosate plus atrazine, EPOST, (lIb plus I lb aiJA); and (7) glyphosate, EPOST (lIb/A) followed by glyphosate, LPOST, (0.751b/A). Although weed apecies and severity differed across locations, giant foxtail (Setariafabert Herrm.), common lambsquarters (Chenopodium album L.), velvetleaf(Albulilon theophrosti Medic.), smooth pigweed (Amaranthus_hybridus L.), common ragweed(Ambrosia artemisiifolia L.), Pennsylvania smartweed(Polygonum pensylvanicum L.), and yellow nutsedge (Cyperus esculentus L.), weremostoftenpresent.The York.Countysite wasdominatedbyJohnsongrass (Sorghum holepense (L.) Pers.). A randomized complete block design with threereplications was used for all studies. Herbicides were applied with a CO,-backpack sprayer that delivered 20 gpa, Above-ground weed biomass and com grain yield were collected at the end of season. Sampleswereovendriedandcom yield wasconvertedto hulAat 15.5%moisture. Locationby treatmentinteractionswereabsentfor fourof six counties,so weed biomass datawerecombinedoverLawrence,Wayne,Lebanon,andJuniatacounties. At these locations, all herbicide treatments effectively controlled the weeds,while weed biomass in the untreated plot averaged 22 I9 lb/A. At Crawford County, the LPOST application of glyphosae was ineffective probably due to the larger weedsand poor spray coverage. At York County, s metolachlor+atrazinepluspendimethalinwastheonlytreatmentnotdifferentfromthecontrol; this wasprimarily due to the presence of Johnsongrass that was not controlled by the PRE treatment. Com yield ranged from an average low of 40 buiA in Wayne County to a high of 160 butA in Lawrence.Comyielddatawas combinedacrosslocationsbecauseof the lackof locationbytreatmentintemctions.Acrosslocationscom yield in theuntreatedplots averaged47 bulA while the herbicide treatments ranged from 86 to 97 bulA. 40
In summary, application timing for glyphosate was generally not as critical in 1999 as it maybe in otheryearsdueto dry weatheranda lackof subsequentweed emergence. Only witha LPOST application, where herbicide deposition may have been impacted because of larger com, weredifferencesin timingobserved. , Assoc. Ext. Agt, Assoc. Prof. of Weed Science, Assoc. Ext. Agt., Asst. Ext. Agt., Assoc. Ext. Agt., Asst. Ext. Agron., Asst. Ext. Agt., and Assoc. Ext. Agt., Dept. of Agronomy, The Pennsylvania State University, University Park, PA 16802 41
- Page 1 and 2: WEED REMOVAL TIMING WITH ROUNDUP RE
- Page 3 and 4: EFFECT OF HERBICIDE RATES AND IRRIG
- Page 5 and 6: 40 Effect of Pronone Applied with A
- Page 7 and 8: Comparisonof Sulfosateand Glyphosat
- Page 9 and 10: N 1175 feet Roundup Ready Studies R
- Page 11 and 12: VIRGINIA TECH'S ONLINE WEED IDENTIF
- Page 13 and 14: WEED CONTROL AND YIELD OF CUT FLOWE
- Page 15 and 16: Table I. Effect of napropamide and
- Page 17 and 18: The Effect of Total Postemergence H
- Page 19 and 20: with commercial fertilizer. In gene
- Page 21 and 22: HERBICIDE APPLICATIONS VERSUS HANDW
- Page 23 and 24: exceeded 4. The success of training
- Page 25 and 26: _u ____ Table2: Estimatesof herbace
- Page 27 and 28: DOUBLE CROP CORN WEED CONTROL IN VI
- Page 29 and 30: ANNUAL WEED AND GRASS CONTROL IN CO
- Page 31 and 32: MANAGING QUACKGRASSINFESTATIONSAS C
- Page 33 and 34: USING HERBICIDE RESISTANT HYBRIDS T
- Page 35 and 36: NICOSULFURONIRIMSULFURON COMBINATIO
- Page 37 and 38: GLYPHOSATE ALONE AND PRECEDED BY PR
- Page 39: ROUNDUPVS. LIBERTY:WHATHAVE WE LEAR
- Page 43 and 44: INFLUENCE OF TIMING ON WEED MANAGEM
- Page 45 and 46: IMPACT OF GLYPHOSATE TIMING AND COR
- Page 47 and 48: PREEMERGENCE HERBICIDES INFLUENCE W
- Page 49 and 50: COMPARISON OF WEED CONTROL SYSTEMS
- Page 51 and 52: Table I Mean Percent Weed Control V
- Page 53 and 54: SMALL GRAIN WEED CONTROL - NEW WEED
- Page 55 and 56: MODE OF ACTION, ABSORPTION, TRANSLO
- Page 57 and 58: INFLUENCE OF CROWNVETCH WITH AND WI
- Page 59 and 60: lRUMPETCREEPER, HONEYVINEMILKWEED,A
- Page 61 and 62: FLUFENACET PLUS METRIBUZIN PLUS ATR
- Page 63 and 64: CONTROLLING ASTERACEAE WEEDS WITH R
- Page 65 and 66: 0... Figure1. GerminationRateof Roo
- Page 67 and 68: BIOLOGICALLY BASED WEED CONTROL STR
- Page 69 and 70: NON·NATIVE VASCULAR FLORA OF BISCA
- Page 71 and 72: principally in ruderal sites. lawns
- Page 73 and 74: EVALUATION OF AZAFENlDIN FOR PREEME
- Page 75 and 76: AUTOMATING MONITORING OF ROADSIDE W
- Page 77 and 78: Table I: Swnmary of brush managemen
- Page 79 and 80: Table I: Sequence codes and general
- Page 81 and 82: IR-4 ORNAMENTAL RESEARCH PROGRESS F
- Page 83 and 84: personnel with many of the illegal
- Page 85 and 86: TOLERANCE OF ORNAMENTAL GROUNDCOVER
- Page 87 and 88: MUGWORT CONTROL WITH CLOPYRALID AND
- Page 89 and 90: POTENTIAL WEEDINESS OF SEVERAL NEW
In summary, application timing for glyphosate was generally not as critical in 1999 as it<br />
maybe in otheryearsdueto dry weatheranda lackof subsequentweed emergence. Only witha<br />
LPOST application, where herbicide deposition may have been impacted because of larger com,<br />
weredifferencesin timingobserved.<br />
, Assoc. Ext. Agt, Assoc. Prof. of <strong>Weed</strong> <strong>Science</strong>, Assoc. Ext. Agt., Asst. Ext. Agt., Assoc. Ext.<br />
Agt., Asst. Ext. Agron., Asst. Ext. Agt., and Assoc. Ext. Agt., Dept. of Agronomy, The<br />
Pennsylvania State University, University Park, PA 16802<br />
41
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