Doctor of Philosophy (PhD)
Plant, Environmental Management and Soil Sciences
Studies were conducted to evaluate growth and reproductive capabilities of creeping rivergrass in response to flood depth, burial depth, desiccation, herbicide programs and interference with rice. Seed production of a natural population of creeping rivergrass was 0.8 seeds per panicle. Germination was 45% and seedling vigor was poor. Flowers from surviving seedlings were male sterile. A 5 and 10 cm flood depth increased fresh weight, stolon length, and node production of creeping rivergrass compared with non-flooded plants. However, depths at 15 and 20 cm did not differ from no-flood; therefore permanent flooding should be delayed until rice can survive a deep flood. Burial of stolons 10 to 20 cm deep prevented emergence and reduced viability. Deep burial of rhizomes prevented emergence but did not reduce viability. Stolon fragmentation due to deep tillage and burial greater than 5 cm, or placement of rhizomes on the soil surface decreases emergence and viability of creeping rivergrass vegetative structures. Desiccating stolons from 35 to 25% of initial fresh weight reduced germination, growth, and potential colonization rate of creeping rivergrass. In competition studies creeping rivergrass above ground biomass was reduced when grown with rice seeded at >45 kg/ha. Rice grain yield was reduced 17 and 29% when creeping rivergrass was planted at densities of 26 and 52 plants/ha, respectively. Emergence of creeping rivergrass was 98% at 31 C and less than 2% at 15 and 11 C suggesting that planting of rice in cooler temperatures may allow a competitive advantage for rice. Creeping rivergrass grown from single node stolon segments, multiple node stolon segments, and rhizomes were treated with various herbicides to evaluate efficacy. A herbicide program for the management of creeping rivergrass should include glyphosate as a burndown treatment prior to planting or during fallow periods. A Clearfield rice variety or hybrid should be selected which allows the use of two applications of imazethapyr, and cyhalofop used as needed throughout the season. Employing a herbicide program coupled with integrated management strategies such as tillage, planting date, and increased rice seeding rates decreases the competitiveness of creeping rivergrass.
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Bottoms, Sunny Lynn, "Integrated management of creeping rivergrass in rice" (2009). LSU Doctoral Dissertations. 1541.
Eric P. Webster