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Full-Text Articles in Population Biology

Herbicide-Resistant Risk Assessment: Response Of Common Nebraska Weeds To Dicamba Dose, Roberto J. Crespo Jul 2011

Herbicide-Resistant Risk Assessment: Response Of Common Nebraska Weeds To Dicamba Dose, Roberto J. Crespo

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

Dicamba-resistant soybeans are being developed to provide an additional herbicide mechanism of action that can be used in soybean, and to provide a tool to help manage or mitigate the evolution of other herbicide-resistant weed populations. The objectives of this thesis were to assess the risk of common Nebraska weeds developing resistance to dicamba, quantify baseline dose-response to dicamba of high-risk weed species, and survey the variability in dicamba dose-response among populations of those species. Twenty-five weed scientists were asked to estimate the risk likelihood of ten weed species evolving resistance to dicamba following the commercialization of dicamba-resistant soybean. Palmer …


Biology, Systematics, Phylogenetic Analysis And Dna Character-Based Species Diagnosis Of The False Root-Knot Nematode Nacobbus Aberrans (Thorne, 1935) Thorne & Allen 1944 (Nemata:Pratylenchidae), Angel Ramirez-Suarez Jun 2011

Biology, Systematics, Phylogenetic Analysis And Dna Character-Based Species Diagnosis Of The False Root-Knot Nematode Nacobbus Aberrans (Thorne, 1935) Thorne & Allen 1944 (Nemata:Pratylenchidae), Angel Ramirez-Suarez

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

The False Root-Knot nematode Nacobbus aberrans is a plant parasitic nematode that causes yield losses in several crops and plant protection agencies have established regulations to prevent infestations from spreading to new agricultural areas. The taxonomic status of the nematode has been the subject of controversy due to wide degree of variation exhibited by the species. This variability has led to the suggestion that N. aberrans is actually a species complex rather than a single species. In order to test this hypothesis, we compared twelve N. aberrans populations, which include isolates from western Nebraska, two distinct regions of Mexico and …


Population Dynamics Of The Western Prickly Pear, Opuntia Macrorhiza (Cactaceae), Kathleen H. Keeler, Brigitte Tenhumberg Jun 2011

Population Dynamics Of The Western Prickly Pear, Opuntia Macrorhiza (Cactaceae), Kathleen H. Keeler, Brigitte Tenhumberg

School of Biological Sciences: Faculty Publications

Although most cacti that have been studied are long lived, following individually marked plants in Boulder County, Colorado, for >7 years, we determined that average life span of Opuntia macrorhiza, the western prickly pear, is 3 years. A few individuals probably live >10 years. Vegetative reproduction, produced by rooting of cladodes, exceeded reproduction by germination and establishment from seeds. Both types of new recruits, from vegetative reproduction and seeds, had higher death rates than established plants. Size and frequency of flowering increased with age, although size both increased and decreased, sometimes dramatically, between years. Flowering correlated more strongly with …