Author
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Webster, Theodore |
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Submitted to: Proceedings of Southern Weed Science Society
Publication Type: Abstract Only Publication Acceptance Date: 1/26/2003 Publication Date: 1/26/2003 Citation: Webster, T.M. 2003. Weed emergence patterns in the Coastal Plain [abstract]. Proceedings of the Southern Weed Science Society. 56:333. Interpretive Summary: Technical Abstract: The ability of a weed to interfere with crop growth is a function of the competitive ability of the weed and its emergence time relative to the crop. Knowledge of weed emergence patterns may help optimize crop production and weed management systems. Seeds of coffee senna (Cassia occidentalis), Florida beggarweed (Desmodium tortuosum), morningglory species (Ipomoea spp.), sicklepod (Senna obtusifolia), and smallflower morningglory (Jaquemontia tamnifolia) were spread in Spring 1999 through 2002. Each plot was replicated 4 times in a RCBD, and no crop was planted. Weed emergence was counted at least every 10 days, after which vegetation was removed using paraquat. Emergence data were fit to growing degree days using a Gompertz function. Ipomoea morningglory spp. were among the earliest emerging weed species, with an estimated median emergence data (ED50) for each year before 1 May. In three of four years, the estimated ED50 for sicklepod ranked it as the second latest species to emerge in this grouping. Smallflower morningglory was the latest emerging weed species evaluated, with ED50 ranging from 14 May to 25 June. Measurements of soil growing degree days (at 5 cm depth) are not adequate to accurately predict emergence. Future studies should evaluate the utility of bio-indicators (e.g. using the phenology of native flora) to indicate when critical environmental requirements have been satisfied. |
