Characterization of Acetolactate Synthase-Inhibiting Herbicide-Resistant Smooth Pigweed and Corn Weed Management Programs Utilizing Mesotrione in Combinations with Other Herbicides

dc.contributor.authorWhaley, Cory Milleren
dc.contributor.committeechairWilson, Henry P.en
dc.contributor.committeememberHagood, Edward Scott Jr.en
dc.contributor.committeememberNessler, Craig L.en
dc.contributor.committeememberWestwood, James H.en
dc.contributor.committeememberBrann, Daniel E.en
dc.contributor.departmentPlant Pathology, Physiology, and Weed Scienceen
dc.date.accessioned2014-03-14T20:07:55Zen
dc.date.adate2005-03-04en
dc.date.available2014-03-14T20:07:55Zen
dc.date.issued2005-03-01en
dc.date.rdate2005-03-04en
dc.date.sdate2005-03-02en
dc.description.abstractRepeated use of acetolactate synthase (ALS)-inhibiting herbicides in recent years has resulted in the selection of 89 weed species resistant to these herbicides. One management strategy that can eliminate or slow the development of resistance is applying mixtures of herbicides with different modes of action. This research involved the characterization of ALS-inhibiting herbicide-resistant smooth pigweed (<i>Amaranthus hybridus</i> L.), as well as investigations on weed management programs in corn (<i>Zea mays</i> L.) utilizing mesotrione, a triketone, in mixtures with other herbicides. ALS-inhibiting herbicide-resistant smooth pigweed biotypes were collected from fields in Virginia, Delaware, Maryland, and Pennsylvania to evaluate response to ALS-inhibiting herbicides and to determine the molecular mechanisms of resistance. Sequencing of the ALS genes from these biotypes revealed two amino acid substitutions known to confer resistance, Ala<sub>122</sub> to Thr and Ser<sub>653</sub> to Asn, and one that has not been previously reported in plants, Asp<sub>376</sub> to Glu. The smooth pigweed biotype with an Asp<sub>376</sub> substitution displayed resistance to four classes of ALS-inhibiting herbicides that included imidazolinone (IMI), sulfonylurea (SU), pyrimidinylthiobenzoate (PTB), and triazolopyrimidine sulfonanilide (TP) chemistries. Transformation of this smooth pigweed ALS gene into <i>Arabidopsis thaliana</i> confirmed that the Asp<sub>376</sub> substitution is responsible for the resistance. Other biotypes that had a substitution at Ala<sub>122</sub> exhibited resistance to an IMI herbicide, little to no resistance to SU herbicides, and increased sensitivity to a PTB and a TP herbicide, whereas, biotypes that had a substitution at Ser<sub>653</sub> exhibited high-level resistance to an IMI herbicide and lower resistance to PTB and SU herbicides. Experiments were also conducted to investigate the effectiveness of mesotrione in preemergence (PRE) and postemergence (POST) corn weed management programs in Virginia. Mesotrione applied PRE in mixtures with <i>S</i>-metolachlor and atrazine controlled common lambsquarters (<i>Chenopodium album</i> L.), smooth pigweed, common ragweed (<i>Ambrosia artemisiifolia</i> L.), and morningglory (<i>Ipomoea</i> spp.) species when a timely rainfall followed application. POST applications of mesotrione controlled common lambsquarters and smooth pigweed, but common ragweed and morningglory species were not always controlled. Common ragweed and morningglory species were controlled by mesotrione in a mixture with atrazine POST. Large crabgrass [<i>Digitaria sanguinalis</i> (L.) Scop.] and giant foxtail (<i>Setaria faberi</i> Herrm.) control was generally better when the ALS-inhibiting herbicides nicosulfuron plus rimsulfuron or rimsulfuron plus thifensulfuron plus atrazine were applied in a mixture with mesotrione. Mixtures of mesotrione with other POST herbicides in a total POST program produced corn yields comparable to standard PRE followed by POST weed management programs.en
dc.description.degreePh. D.en
dc.identifier.otheretd-03022005-225622en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-03022005-225622/en
dc.identifier.urihttp://hdl.handle.net/10919/26341en
dc.publisherVirginia Techen
dc.relation.haspart05cwhaley_Chapter2.pdfen
dc.relation.haspart12cwhaley_vita.pdfen
dc.relation.haspart11cwhaley_Chapter8.pdfen
dc.relation.haspart10cwhaley_Chapter7.pdfen
dc.relation.haspart09cwhaley_Chapter6.pdfen
dc.relation.haspart07cwhaley_Chapter4.pdfen
dc.relation.haspart08cwhaley_Chapter5.pdfen
dc.relation.haspart01cwhaley_TitleAbstract.pdfen
dc.relation.haspart02cwhaley_Acknowledgments.pdfen
dc.relation.haspart03cwhaley_TableofContents.pdfen
dc.relation.haspart04cwhaley_Chapter1.pdfen
dc.relation.haspart06cwhaley_Chapter3.pdfen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectthifensulfuronen
dc.subjectALS mutationen
dc.subjectAmaranthus hybridus L.en
dc.subjectweed controlen
dc.subjectnicosulfuronen
dc.subjecttriazolopyrimidineen
dc.subjectimidazolinoneen
dc.subjectherbicide resistanceen
dc.subjectrimsulfuronen
dc.subjectpyrimidinyloxybenzoateen
dc.subjectatrazineen
dc.subjectsulfonylureaen
dc.subjectS-metolachloren
dc.titleCharacterization of Acetolactate Synthase-Inhibiting Herbicide-Resistant Smooth Pigweed and Corn Weed Management Programs Utilizing Mesotrione in Combinations with Other Herbicidesen
dc.typeDissertationen
thesis.degree.disciplinePlant Pathology, Physiology, and Weed Scienceen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.namePh. D.en

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