Theses and Dissertations at Montana State University (MSU)
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Item Management of Kochia (Bassia scoparia) in a time of herbicide resistance(Montana State University - Bozeman, College of Agriculture, 2020) Lim, Charlemagne Ajoc; Chairperson, Graduate Committee: Alan T. Dyer; Alan Dyer and Prashant Jha were co-authors of the article, 'Kochia (Bassia scoparia) growth and fecundity under different crops and weed densities' submitted to the journal 'Weed science journal' which is contained within this dissertation.; Alan Dyer and Prashant Jha were co-authors of the article, 'Survival and reproductive fitness of glyphosate-resistant kochia (Bassia scoparia) in the presence of glyphosate' submitted to the journal 'Weed technology journal' which is contained within this dissertation.; Alan Dyer and Prashant Jha were co-authors of the article, 'Survival, growth and fecundity of Dicamba-resistant kochia (Bassia scoparia) in the absence and presence of Dicamba' submitted to the journal 'Weed technology journal' which is contained within this dissertation.Kochia [Bassia scoparia (L.) A. J. Scott] is one of the most troublesome weeds in the US Great Plains. This is exacerbated by the development of herbicide-resistant kochia populations which necessitates more ecologically driven approaches for its control. This research examined the competitive effects of four crops (sugar beet, soybean, barley and corn) in combination with kochia densities (3, 13, 24, 47, 94 and 188 plants m-2) on kochia development and kochia seed production. Corn had greatest effect in reducing kochia biomass and seed production. Barley had greatest effect in delaying kochia flowering which happened after barley senesced at 113 days after kochia emergence. Soybean and sugar beet had the least effect in reducing kochia biomass and seed production, respectively, relative to fallow. This research also reports the fitness of glyphosate-resistant kochia and dicamba-resistant kochia in the presence and absence of glyphosate and dicamba selection, respectively, under field conditions. Glyphosate-resistant kochia showed limited fitness cost (less seed weight and seed radicle length relative to the susceptible) in the absence of glyphosate selection and reduced reproductive fitness (seed production) in the presence of increasing glyphosate selection. In the absence of dicamba selection, dicamba-resistant kochia showed a fitness cost (reduced growth and seed production relative to the susceptible) associated with dicamba resistance with greater fitness cost observed with increased level of resistance. Dicamba-resistant kochia also showed reduced reproductive fitness (seed production) in the presence of increasing dicamba selection. Overall, this research provides information on the growth and reproductive fitness of glyphosate-resistant kochia and dicamba-resistant kochia in the presence and absence of glyphosate and dicamba selection, respectively. Furthermore, this research provides insights on the competitive abilities of different but financially viable rotational crops for kochia management in Montana.Item Confirmation and management of glyphosate-resistant Kochia (Kochia scoparia) in Montana(Montana State University - Bozeman, College of Agriculture, 2015) Kumar, Vipan; Chairperson, Graduate Committee: Prashant Jha; Prashant Jha and Nicholas Reichard were co-authors of the article, 'Occurrence and characterization of Kochia (Kochia scoparia) accessions with resistance to glyphosate in Montana' in the journal 'Weed technology journal' which is contained within this thesis.; Prashant Jha, Darci Giacomini, Eric Westra and Philip Westra were co-authors of the article, 'Molecular basis of evolved resistance to glyphosate and acetolactate synthase-inhibitor herbicides in Kochia (Kochia scoparia) accessions from Montana' submitted to the journal 'Weed science journal' which is contained within this thesis.; Prashant Jha was a co-author of the article, 'Impact of EPSPS gene amplification and intraspecific competition on fitness of glyphosate-resistan Kochia scoparia inbreds' submitted to the journal 'PLoS one journal' which is contained within this thesis.; Prashant Jha was a co-author of the article, 'Effective preemergence and postemergence herbicide programs for Kochia control' in the journal 'Weed technology journal' which is contained within this thesis.; Prashant Jha was a co-author of the article, 'Influence of herbicides applied postharvest in wheat stubble on control, fecundity, and progeny fitness of Kochia scoparia in the US Great Plains' in the journal 'Crop protection journal' which is contained within this thesis.; Prashant Jha was a co-author of the article, 'Influence of glyphosate timing on Kochia (Kochia scoparia) demographics in glyphosate-resistant sugar beet' submitted to the journal 'Weed technology journal' which is contained within this thesis.; Prashant Jha was a co-author of the article, 'Control of volunteer glyphosate-resistant canola in glyphosate-resistant sugar beet' in the journal 'Weed technology journal' which is contained within this thesis.Kochia (Kochia scoparia L.) is one of the most problematic weeds in cropland and non-cropland areas of the US Great Plains. This research confirms the first report on glyphosate-resistant (GR) K. scoparia in Montana, and elucidates the mechanisms of glyphosate and ALS-inhibitor resistance, growth and reproductive fitness of GR K. scoparia, and its management. This research also reports the response of K. scoparia demographics to glyphosate timings in GR sugar beet and evaluate herbicide options for managing volunteer GR canola in GR sugar beet. Based on whole-plant dose-response experiments, four GR K. scoparia accessions (JOP01, GIL01, CHES01, CHES02) had 4.6 to 11-fold levels of resistance to glyphosate compared to a glyphosate-susceptible (GS) accession. Confirmed GR K. scoparia accessions (GIL01, JOP01, and CHES01) also exhibited 9.3- to 30-fold resistance to sulfonylurea herbicide (ALS inhibitors). Results from PCR, quantitative PCR, and immunoblotting assays indicated that EPSPS gene amplification (~ 4 to 10 copies) and single point mutation at Pro197 in ALS gene conferred resistance to glyphosate and ALS-inhibitors, respectively. Inbred lines of GR K. scoparia (CHES01 and JOP01) with 2- to 14-fold amplification of the EPSPS gene did not confer any growth- or fecundity-related fitness cost. From a management standpoint, acetochlor + atrazine, S-metolachlor + atrazine + mesotrione, and sulfentrazone applied PRE and paraquat + atrazine, paraquat + linuron, and paraquat + metribuzin applied POST or in postharvest wheat stubble provided effective (> or = 91%) control of K. scoparia. In GR sugar beet, sequential applications of glyphosate (6-leaf fb 10-leaf stage of sugar beet) reduced survival, biomass and seed production of K. scoparia plants in cohort 1 and 2; however, an additional application of glyphosate at the canopy closure stage of sugar beet was needed to prevent seed production from the late-emerging K. scoparia (cohort 3). Ethofumesate (4,200 g ha -1) PRE followed by sequential POST triflusulfuron methyl (17.5 g ha -1) was the most effective treatment for managing volunteer GR canola in GR sugar beet. Overall, this research demonstrates the adaptability of K. scoparia evolving resistance to glyphosate and ALS inhibitors, and suggest the need for adoption of integrated weed management practices.Item Occurrence and characterization of dicambre resistant Kochia (Kochia scoparia) in Montana(Montana State University - Bozeman, College of Agriculture, 1998) Hackett, Josette LynnItem Characteristics of differential herbicide response in sulfonylurea-resistant Kochia scoparia accessions(Montana State University - Bozeman, College of Agriculture, 1992) Sivakumaran, KailayapillaiItem Molecular studies of dicamba-resistant Kochia scoparia L.(Montana State University - Bozeman, College of Agriculture, 2002) Kern, Anthony JohnItem Management, inheritance, and gene flow of resistance to chlorsulfuron in Kochia scoparia L. (Schrad)(Montana State University - Bozeman, College of Agriculture, 1991) Mulugeta, Dawit