No description available.

No description available.

Thesis (M.S.)--University of Wyoming, 2009. / Title from PDF title page (viewed on May 24, 2010). Includes bibliographical references (p. 50-53).

Russian knapweed (Acroptilon repens) is an invasive perennial forb that has become well established in much of the western United States and Canada since the late 1800s. Aminopyralid is a relatively new pyridine carboxylic acid herbicide registered for use on rangelands and has provided excellent control of Russian knapweed in many studies. Research trials were conducted on two adjacent plot sites at Dinosaur National Monument to evaluate the effects of a single spring goat grazing paired with a fall application of aminopyralid at 0, 53, 70, 88, and 105 g ae ha-1 on Russian knapweed control. Russian knapweed density, canopy cover, and biomass were reduced to 0 or near 0 by all rates of aminopyralid, regardless of grazing treatment. Conversely, desirable grass cover and biomass increased at all rates of aminopyralid regardless of grazing treatment. Aminopyralid provided excellent control of Russian knapweed at all rates tested. Desirable perennial grass species have the potential to be injured when growth regulator herbicides are used for broadleaf weed control. Greenhouse trials performed at Utah State University and field trials performed in Logan, UT from 2009&ndash2011 evaluated tolerance and response of six native perennial bunchgrasses to growth regulator herbicides. Grasses used in the study included tall wheatgrass, bluebunch wheatgrass, Great Basin wildrye, Indian ricegrass, big bluegrass, and bottlebrush squirreltail. Two rates each of aminopyralid, aminocyclopyrachlor, and clopyralid were evaluated. Herbicide test rates were based on the labeled rate for control of Russian knapweed and other creeping perennials. Tolerance to herbicides varied among grass species. Petri&ndashdish trials showed reductions in root length by all three herbicides in all six speceis 14 days after treatment (DAT). Shoot length was significantly reduced by both rates of aminopyralid (123 and 246 g ae ha-1) and 280 g ai ha-1 of amincyclopyrachlor. The same species were evaluated in the field and greenhouse in response to postemergence applications of the same herbicides. Of the six grass species tested, &lsquoSherman&rsquo big bluegrass appeared to be highly tolerant to aminopyralid, clopyralid, and aminocyclopyrachlor, and &lsquoMagnar&rsquo Great Basin wildrye and Anatone bluebunch wheatgrass appeared to be the most sensitive to aminopyralid and aminocyclopoyrachlor in both the field and the greenhouse.

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

A culture system was established for mass rearing of the Russian knapweed nematode, Subanguina picridis (Kirjanova) Brzeski. This system consisted of two parts; a shoot culture system used as the host plant source for the nematode culture, and a monoxenic nematode culture system. The nematode developed and reproduced in this system. Galls were induced on the leaves, stems, and shoot tips of cultured Russian knapweed (Acroptilon repens (L.) DC.) shoots. After 3 months in culture, the nematode number per petri dish increased from the initial 50 inoculated to 7,000-10,000, a 140 to 200 fold increase. This study represents the first time that an above-ground gall forming nematode has been propagated in vitro. It also represents a unique monoxenic nematode culture system to mass rear above-ground endoparasitic plant nematodes. / Various factors, including tissue type, tissue age, medium, and temperature, which affect the formation and development of galls, were examined. The nematode failed to reproduce in callus tissues, and it could not develop beyond the 4th stage in excised root cultures. The optimum incubation conditions determined were: 60-80 $ mu$molm$ sp{-2}$s$ sp{-1}$ light intensity, 20 C temperature, and 4-8 mm for shoot length. / The virulence of cultured nematodes was tested in the greenhouse on Russian knapweed seedlings and vegetative shoots from root segments. The results demonstrated the feasibility and application of this novel mass production system. Nematodes produced in this system were virulent and the growth rate of infested Russian knapweed were reduced.

Thesis (Ph. D.)--University of Wyoming, 2006. / Title from PDF title page (viewed on April 16, 2008). Includes bibliographical references.

Russian knapweed (Acroptilon repens) is an invasive perennial forb that has become well established in much of the western United States and Canada since the late 1800s. Aminopyralid is a relatively new pyridine carboxylic acid herbicide registered for use on rangelands and has provided excellent control of Russian knapweed in many studies. Research trials were conducted on two adjacent plot sites at Dinosaur National Monument to evaluate the effects of a single spring goat grazing paired with a fall application of aminopyralid at 0, 53, 70, 88, and 105 g ae ha-1 on Russian knapweed control. Russian knapweed density, canopy cover, and biomass were reduced to 0 or near 0 by all rates of aminopyralid, regardless of grazing treatment. Conversely, desirable grass cover and biomass increased at all rates of aminopyralid regardless of grazing treatment. Aminopyralid provided excellent control of Russian knapweed at all rates tested. Desirable perennial grass species have the potential to be injured when growth regulator herbicides are used for broadleaf weed control. Greenhouse trials performed at Utah State University and field trials performed in Logan, UT from 2009&ndash2011 evaluated tolerance and response of six native perennial bunchgrasses to growth regulator herbicides. Grasses used in the study included tall wheatgrass, bluebunch wheatgrass, Great Basin wildrye, Indian ricegrass, big bluegrass, and bottlebrush squirreltail. Two rates each of aminopyralid, aminocyclopyrachlor, and clopyralid were evaluated. Herbicide test rates were based on the labeled rate for control of Russian knapweed and other creeping perennials. Tolerance to herbicides varied among grass species. Petri&ndashdish trials showed reductions in root length by all three herbicides in all six speceis 14 days after treatment (DAT). Shoot length was significantly reduced by both rates of aminopyralid (123 and 246 g ae ha-1) and 280 g ai ha-1 of amincyclopyrachlor. The same species were evaluated in the field and greenhouse in response to postemergence applications of the same herbicides. Of the six grass species tested, &lsquoSherman&rsquo big bluegrass appeared to be highly tolerant to aminopyralid, clopyralid, and aminocyclopyrachlor, and &lsquoMagnar&rsquo Great Basin wildrye and Anatone bluebunch wheatgrass appeared to be the most sensitive to aminopyralid and aminocyclopoyrachlor in both the field and the greenhouse.

No description available.