Author
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Webster, Theodore |
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Submitted to: Weed Science
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 4/24/2003 Publication Date: 12/1/2003 Citation: Webster, T.M. 2003. High temperatures and durations of exposure reduce nutsedge (Cyperus spp.) tuber viability. Weed Science. 51:1010-1015. Interpretive Summary: The widely used fumigant methyl bromide has been identified as a potential ozone-depleting substance and its use will soon be stopped. Research to find alternatives to manage a wide-range of pests in high value vegetable crops is underway throughout the world. Without methyl bromide, it is feared that purple and yellow nutsedge will cause significant crop yield loss. Currently nutsedges are among the most troublesome weeds of vegetable crops in the southeast US. Nutsedges rely on underground tubers as the primary means of reproducing. Soil solarization has been proposed as an alternative to methyl bromide for controlling nutsedges, however little is known about the relationship between soil solarization and nutsedge tuber viability. Nutsedge tuber viability was reduced when temperatures > 45 C. Relative to purple nutsedge, yellow nutsedge tubers were more sensitive to temperatures of 45, 50, and 55 C. Tuber viability at 60 C was similar with both nutsedges. With long enough durations of exposure, both purple and yellow nutsedge tubers were killed at temperatures > 50 C. However, application of this data to field situations is limited using present technology, as the soil temperature can not be raised to high enough levels for solarization. However, there is the potential to reduce new tuber production with the use of polyethylene mulch. Technical Abstract: Soil solarization has been proposed as an alternative to methyl bromide for controlling nutsedges, however little is known about the relationship between soil solarization and nutsedge tuber viability. Combinations of elevated temperatures and durations of exposure were evaluated for their affect on purple nutsedge and yellow nutsedge tuber viability and new tuber production in growth chamber studies. Estimates of the duration of exposure at each temperature that reduced nutsedge growth parameters 50% (I50) were supplied by log-logistic regression analysis. Nutsedge tuber viability was reduced when temperatures > 45 C. Relative to purple nutsedge, yellow nutsedge tuber viability had smaller I50 values for 45, 50, and 55 C. Tuber viability I50 at 60 C was similar with both nutsedges. The I50 for the production of new purple nutsedge tubers at 50 C was larger than yellow nutsedge. However, there were no differences between species in I50 for new tuber production at higher temperatures. With long enough durations of exposure, both purple and yellow nutsedge tubers were killed at temperatures > 50 C. However, application of this data to field situations is limited using present technology, as the soil temperature can not be raised to high enough levels for solarization. |
