Vol. 54â2000 - NorthEastern Weed Science Society
Vol. 54â2000 - NorthEastern Weed Science Society Vol. 54â2000 - NorthEastern Weed Science Society
EVALUATION OF METOLACHLOR AND PEBULATE IN PLASTICUL TURE TOMATO W.A. Bailey, H.P. Wilson, H.E. Hohlt, and T.E. Hines' ABSTRACT Tomato(Lycopersicum esculentum mill.) productionis significantin southernandmid-Atlantic regions of the U.S. There are approximately 4200 acres of tomato grownon the Eastern Shore of Virginia. The expectedcancellationof methyl bromideregistrationis encouraginggrowersto searchforalternativemeansof weed controlfortomatogrown underplastic. A suitable replacementformethylbromidewouldbeof obviousbenefit. Nutsedge species (Cyperus spp.) are a majorproblemin tomatoproductionprimarilydue to the highly competitivenatureof these weeds andtheirfrequentpenetrationof plasticbedcovers. Two herbicidesthatsuppressgrowth of nutsedgespecies aremetolachlorandpebulate.Metolachlorsuppressesyellow nutsedge (Cyperus esculentus L.) while pebulate can suppress yellow and purple nutsedge (Cyperus rotundus L.) buttomatotoleranceto theseherbicidesappliedunderplasticis not known. Fieldexperimentswere initiatedin 1999to evaluatetoleranceof tomato to s-metolachlorand pebulate. Study design was a randomized complete block with three replications. Following herbicideapplication,bedswere coveredwithblackplasticand'AgroSet'tomatowere transplanted 12 in. apart into the beds. Treatments included s-metolachlor (0.75, 1.0, and 1.5lb ai/A), pebulate (3.0, 4.5, and 6.0 Ib ai/A), and a nontreated check. All other production practices werestandardaccordingto VirginiaExtensionrecommendations.Cropinjurywas visually estimatedat 2, 3, and9 wk aftertreatment(WAn. Six plantsfromeach one-rowplot were hand-harvested three times to achieve optimum yield, quality, and grade. Tomato fruit were gradedandweighed at eachharvestdate. Fruitfromeachplot were separatedinto culls (malformed tomato or tomato with less than a 2.25 in-diameter), medium (3.5 in) sizes. Therewere no significanttreatmenteffects forinjuryfoundbetweenherbicide-treated tomato at eachinjuryevaluation. Injuryfromherbicidetreatmentswas from 11 to19% at 2 WAT, 7 to 17% at 3 WAT, and 5 to 11% at 9 WAT. Iqjwy was numerically, although not significantly, highest from s-metolachlor at 1.51b/A (19, 17 and 11% at 2, 3, and 9 WAT, respectively) and lowest from s-metolachlor at 0.75 Ib/A (13, II, and 5% at 2, 3, and 9 WAT, respectively). Injury from pebulate at any rate was 12 to 13%at2 WAT, 7 to 11% at 3 WAT, and 5 to 9% at 9 WAT. Herbicidetreatmentsgenerallyhadlittleor no effect on tomatogradeandtotalyield when compared to nontreated tomato. Large fruit from each treatment made up the highest percentage of yield at each of the three harvest periods. These data illustrate the potential for s-metolachlor andpebulateuse in tomatogrown underplastic. Futureresearchwill investigatethe use of s metolachlorandpebulateunderplasticatthese sameratesaloneandwith soil fumigationwith 1,3-dichloropropeneplus chloropicrin. JOraduateResearchAssistant,Professor,ExtensionSpecialist,andResearchSpecialistSenior, respectively, Virginia Polytechnic Institute and State University, Eastern Shore Agricultural Research and Extension Center, Painter, VA 23420-2827. 20
HERBICIDE APPLICATIONS VERSUS HANDWEEDING HERBACEOUS PERENNIAL PLUGS: POTENTIAL FOR CROP DAMAGE AND CROP LOSS AnnamariePennucciI ABSTRACT Handweeding and one-time herbicide applications were evaluated for their relative effectiveness in reducing weed populations indigenousto herbaceous perennialplant production. Commerciallyavailableherbaceous plugs, weed infested during propagation and prior to receipt, were transplanted into finishing4 inch pots and weed and crop growth evaluated. Crop plants were grouped into categories by leaf sizeand the effectivenessof weed control measureswas evaluated during the season. Handweeding smalland mid-sizedcrops resulted in greater crop damage and loss than herbicideapplications despite the relative ineffectivenessof post-emergent applications of broad spectrum herbicides.Handweeding large-sized crops resulted in greater crop densities and greater weed control than post-emergent applications but handweeding efforts had to be repeated to maintain that effectiveness. Handweeding followed by pre-emergent applications offers the best compromise between potential crop loss and weediness. INTRODUCTION The production of herbaceous perennial ornamental plants for both wholesale and retail sales in the Northeast typically begins with the importation of dormant or near-dormant plugs from large mid-western propagators. Plug sizes may vary from an average minimum 3/4 inch to an average maximum 2.25 inch diameter and plugs may bebare-root, in soil or sphagnum or produced in variously sized trays. For most retail sales, dormant plugs are received in late winter/early spring and transplanted to the final pot sizes and "grown-on" in cool greenhouses, unheated hoop houses, under shade clothes, on landscape fabric, or directly on sales benches. In recent years, numerous complaints have been made concerning the receipted condition of these plugs; with especial emphasis placed on their "weediness". In various circumstances, weed growth resumed in advance of crop growth; concommitant with crop growth or followed but later overshadowed crop growth. The greatest severity of complaint concerned those weeds that outgrew the crop to the extent that the crop could not bedistinguished from the weeds or was lost completely. MATERIALS AND METHODS A brief survey was taken to determine which species of herbaceous perennials plugs were most likely to harbor weeds and if the expected size of the crop influenced, in any way, the severity of weed interactions. The weed species most commonly encountered were determined and the proportion of the crop lost when weed control measures were not taken was estimated. Weed control efforts were initiated on two crops each of three different size categories; control efforts included handweeding and one-time herbicide applications. Handweeding was evaluated at plug planting by counting and identifying weed populations as nursery employees removed them; the size of the remaining plug was estimated. Pots were placed in a special holding area that maintained the normal nursery regime (irrigation, fertilization) and weeds counts were made I, 2, 4 and 8 weeks after planting (wap). , Northeast Turf and Ornamental Research, Raymond. N.H. 03077 21
- Page 1 and 2: WEED REMOVAL TIMING WITH ROUNDUP RE
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- Page 43 and 44: INFLUENCE OF TIMING ON WEED MANAGEM
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EVALUATION OF METOLACHLOR AND PEBULATE IN PLASTICUL TURE TOMATO<br />
W.A. Bailey, H.P. Wilson, H.E. Hohlt, and T.E. Hines'<br />
ABSTRACT<br />
Tomato(Lycopersicum esculentum mill.) productionis significantin southernandmid-Atlantic<br />
regions of the U.S. There are approximately 4200 acres of tomato grownon the Eastern Shore of<br />
Virginia. The expectedcancellationof methyl bromideregistrationis encouraginggrowersto<br />
searchforalternativemeansof weed controlfortomatogrown underplastic. A suitable<br />
replacementformethylbromidewouldbeof obviousbenefit. Nutsedge species (Cyperus spp.)<br />
are a majorproblemin tomatoproductionprimarilydue to the highly competitivenatureof these<br />
weeds andtheirfrequentpenetrationof plasticbedcovers. Two herbicidesthatsuppressgrowth<br />
of nutsedgespecies aremetolachlorandpebulate.Metolachlorsuppressesyellow nutsedge<br />
(Cyperus esculentus L.) while pebulate can suppress yellow and purple nutsedge (Cyperus<br />
rotundus L.) buttomatotoleranceto theseherbicidesappliedunderplasticis not known.<br />
Fieldexperimentswere initiatedin 1999to evaluatetoleranceof tomato to s-metolachlorand<br />
pebulate. Study design was a randomized complete block with three replications. Following<br />
herbicideapplication,bedswere coveredwithblackplasticand'AgroSet'tomatowere<br />
transplanted 12 in. apart into the beds. Treatments included s-metolachlor (0.75, 1.0, and 1.5lb<br />
ai/A), pebulate (3.0, 4.5, and 6.0 Ib ai/A), and a nontreated check. All other production practices<br />
werestandardaccordingto VirginiaExtensionrecommendations.Cropinjurywas visually<br />
estimatedat 2, 3, and9 wk aftertreatment(WAn. Six plantsfromeach one-rowplot were<br />
hand-harvested three times to achieve optimum yield, quality, and grade. Tomato fruit were<br />
gradedandweighed at eachharvestdate. Fruitfromeachplot were separatedinto culls<br />
(malformed tomato or tomato with less than a 2.25 in-diameter), medium (3.5 in) sizes.<br />
Therewere no significanttreatmenteffects forinjuryfoundbetweenherbicide-treated tomato<br />
at eachinjuryevaluation. Injuryfromherbicidetreatmentswas from 11 to19% at 2 WAT, 7 to<br />
17% at 3 WAT, and 5 to 11% at 9 WAT. Iqjwy was numerically, although not significantly,<br />
highest from s-metolachlor at 1.51b/A (19, 17 and 11% at 2, 3, and 9 WAT, respectively) and<br />
lowest from s-metolachlor at 0.75 Ib/A (13, II, and 5% at 2, 3, and 9 WAT, respectively). Injury<br />
from pebulate at any rate was 12 to 13%at2 WAT, 7 to 11% at 3 WAT, and 5 to 9% at 9 WAT.<br />
Herbicidetreatmentsgenerallyhadlittleor no effect on tomatogradeandtotalyield when<br />
compared to nontreated tomato. Large fruit from each treatment made up the highest percentage<br />
of yield at each of the three harvest periods. These data illustrate the potential for s-metolachlor<br />
andpebulateuse in tomatogrown underplastic. Futureresearchwill investigatethe use of s<br />
metolachlorandpebulateunderplasticatthese sameratesaloneandwith soil fumigationwith<br />
1,3-dichloropropeneplus chloropicrin.<br />
JOraduateResearchAssistant,Professor,ExtensionSpecialist,andResearchSpecialistSenior,<br />
respectively, Virginia Polytechnic Institute and State University, Eastern Shore Agricultural<br />
Research and Extension Center, Painter, VA 23420-2827.<br />
20
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