dc.contributor.author	Whaley, Cory Miller	en
dc.contributor.committeechair	Wilson, Henry P.	en
dc.contributor.committeemember	Hagood, Edward Scott Jr.	en
dc.contributor.committeemember	Nessler, Craig L.	en
dc.contributor.committeemember	Westwood, James H.	en
dc.contributor.committeemember	Brann, Daniel E.	en
dc.contributor.department	Plant Pathology, Physiology, and Weed Science	en
dc.date.accessioned	2014-03-14T20:07:55Z	en
dc.date.adate	2005-03-04	en
dc.date.available	2014-03-14T20:07:55Z	en
dc.date.issued	2005-03-01	en
dc.date.rdate	2005-03-04	en
dc.date.sdate	2005-03-02	en
dc.description.abstract	Repeated 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.degree	Ph. D.	en
dc.identifier.other	etd-03022005-225622	en
dc.identifier.sourceurl	http://scholar.lib.vt.edu/theses/available/etd-03022005-225622/	en
dc.identifier.uri	http://hdl.handle.net/10919/26341	en
dc.publisher	Virginia Tech	en
dc.relation.haspart	05cwhaley_Chapter2.pdf	en
dc.relation.haspart	12cwhaley_vita.pdf	en
dc.relation.haspart	11cwhaley_Chapter8.pdf	en
dc.relation.haspart	10cwhaley_Chapter7.pdf	en
dc.relation.haspart	09cwhaley_Chapter6.pdf	en
dc.relation.haspart	07cwhaley_Chapter4.pdf	en
dc.relation.haspart	08cwhaley_Chapter5.pdf	en
dc.relation.haspart	01cwhaley_TitleAbstract.pdf	en
dc.relation.haspart	02cwhaley_Acknowledgments.pdf	en
dc.relation.haspart	03cwhaley_TableofContents.pdf	en
dc.relation.haspart	04cwhaley_Chapter1.pdf	en
dc.relation.haspart	06cwhaley_Chapter3.pdf	en
dc.rights	In Copyright	en
dc.rights.uri	http://rightsstatements.org/vocab/InC/1.0/	en
dc.subject	thifensulfuron	en
dc.subject	ALS mutation	en
dc.subject	Amaranthus hybridus L.	en
dc.subject	weed control	en
dc.subject	nicosulfuron	en
dc.subject	triazolopyrimidine	en
dc.subject	imidazolinone	en
dc.subject	herbicide resistance	en
dc.subject	rimsulfuron	en
dc.subject	pyrimidinyloxybenzoate	en
dc.subject	atrazine	en
dc.subject	sulfonylurea	en
dc.subject	S-metolachlor	en
dc.title	Characterization of Acetolactate Synthase-Inhibiting Herbicide-Resistant Smooth Pigweed and Corn Weed Management Programs Utilizing Mesotrione in Combinations with Other Herbicides	en
dc.type	Dissertation	en
thesis.degree.discipline	Plant Pathology, Physiology, and Weed Science	en
thesis.degree.grantor	Virginia Polytechnic Institute and State University	en
thesis.degree.level	doctoral	en
thesis.degree.name	Ph. D.	en

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

Files

Original bundle

Collections