Control of Lepidium latifolium and restoration of native grasses Public Deposited

http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/6682x855m

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  • Lepidium latifolium L. (perennial pepperweed, LEPLA) is an exotic invader throughout western North America. At Malheur National Wildlife Refuge (MNWR) in southeast Oregon, it has invaded about 10% of meadow habitats that are important for wildlife. This study's objective was to determine the most effective and least environmentally harmful treatment to control this weed and restore native vegetation using integrated pest management techniques. During summer 1995, nine 0.24-ha plots in three meadows infested with L. latifolium at MNWR were randomly assigned to a treatment with metsulfuron methyl herbicide, chlorsulfuron herbicide, disking, burning, herbicide (metsulfuron methyl or chlorsulfuron) then disking, herbicide (metsulfuron methyl or chlorsulfuron) then burning, or untreated. Changes in L. latifolium ramet densities and basal cover of vegetation, litter, and bare soil were evaluated in 1996 and 1997. Sheep grazing was evaluated as a treatment for reduction in flower production along roadsides and levees during summer 1997. Revegetation treatments of seeding, transplanting or natural (untreated) revegetation were attempted at plots treated with chlorsulfuron, disking, chlorsulfuron then disking, and at untreated plots from October 1996 through September 1997. Chlorsulfuron was the most effective control treatment with greater than 97% reduction in L. latifolium ramet densities two years after treatment. Metsulfuron methyl was an effective control (greater than 93% reduction) for one year. Disking was ineffective. Burning was ineffective at the one site where sufficient fine fuels existed to carry fire. Herbicide treatments were associated with increased grass and reduced forb cover. Disking was associated with reduced grass and litter cover. Disking combined with either herbicide treatment was associated with reductions in all plant cover (49 to 100%), increased bare ground, and invasion by other weedy species such as Cirsium arvense (L.) Scop. (Canada thistle, CIRAR) and Bromus tectorum L. (cheatgrass, BROTE). Ungrazed L. latifolium averaged 4513 flowers per ramet. Sheep grazing reduced L. latifolium flower production by at least 98%. Revegetation treatments were unnecessary in sites treated with chlorsulfuron and were ineffective at all treatment sites.
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  • File scanned at 300 ppi (Monochrome, 256 Grayscale, 24-bit Color) using Capture Perfect 3.0.82 on a Canon DR-9080C in PDF format. CVista PdfCompressor 4.0 was used for pdf compression and textual OCR.
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  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2012-08-29T17:57:28Z (GMT) No. of bitstreams: 1 LawsMargaretS2000.pdf: 6000688 bytes, checksum: de61e08fad3b0048468ecf5a86ee120a (MD5)
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  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2012-09-04T16:29:30Z (GMT) No. of bitstreams: 1 LawsMargaretS2000.pdf: 6000688 bytes, checksum: de61e08fad3b0048468ecf5a86ee120a (MD5)

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