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Title: EFFECT OF COGONGRASS (IMPERATA CYLINDRICA) RESIDUES ON GERMINATION AND SEEDLING GROWTH OF GRASSES AND SELECTED WEEDS

Author
item Koger Iii, Clifford
item Bryson, Charles

Submitted to: Weed Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/18/2004
Publication Date: 4/1/2004
Citation: Koger III, C.H., Bryson, C.T. 2004. Effect of cogongrass (Imperata cylindrica) residues on germination and seedling growth of grasses and selected weeds. Weed Technology. 18:236-242.

Interpretive Summary: Cogongrass is among the most troublesome weeds worldwide and thrives in infrequently cultivated areas, roadways, forests, pastures, and pine plantations of the gulf state region of the southeastern United States. It is extremely competitive with other plant species for nutrients, light, water, and physical space. However, little information is available regarding the potential for cogongrass to exude chemicals that may inhibit germination and/or growth of other plant species. Laboratory studies were conducted at the Southern Weed Science Research Unit, Stoneville, MS to study the effects of liquid extracts of cogongrass foliage and root residues on germination and seedling growth of various grass and broadleaf species. Cogongrass residue extracts (foliage and root) inhibited germination (up to 88% reduction) and seedling growth up to (96% reduction)of all species except hemp sesbania. These results indicate that cogongrass may contain chemicals that inhibit growth of other plant species and that may contribute to its invasiveness and extreme competitiveness.

Technical Abstract: The effects of cogongrass foliage and root residues on germination and radicle and coleoptile growth of barnyardgrass, browntop millet, common bermudagrass, hemp sesbania, Italian ryegrass, and prickly sida were investigated in laboratory experiments. Liquid extracts of cogongrass foliage and root residues at concentrations of 0, 0.25, 0.5, 1, 2, 4, and 8% were evaluated on common bermudagrass and Italian ryegrass. Effects of 8% foliage and root extracts were investigated on hemp sesbania, prickly sida, barnyardgrass, and browntop millet. Cogongrass residues (foliage and root) at concentrations as low as 0.5% inhibited germination and seedling growth of all species except hemp sesbania. Germination was reduced by as much as 88%, and radicle and coleoptile growth by as much as 96% at the highest residue concentrations. Foliage and root residues of cogongrass reduced germination and seedling growth of all affected grass and broadleaf species at similar levels. Results indicate that liquid extracts of cogongrass may contain chemicals that may contribute to its invasiveness and extreme competitiveness.