Author
 |
Webster, Theodore |
|
Submitted to: University of Georgia Research Report
Publication Type: Experiment Station Publication Acceptance Date: 9/1/2002 Publication Date: 10/1/2002 Citation: Webster, T.M. 2002. What soil temperatures will kill nutsedge tubers? 2002 University of Georgia Vegetable Research and Extension Report. p.88-97. Interpretive Summary: In Georgia vegetable production, the foundation of for pest management has been methyl bromide. However, methyl bromide is suspected to contribute to ozone depletion and its use is scheduled to cease in 2005. Solarization has been one proposed alternative to methyl bromide. Nutsedges are the most troublesome weeds of vegetable crops in the Southeast U.S. There are few alternatives for nutsedge control in many vegetable crops. This study was conducted to determine the relationship between temperature and duration of exposure on purple and yellow nutsedge tuber viability. Tubers were exposed to temperatures ranging from 35 to 65C (in 5C increments) for 12 durations (ranging from 0 to 256 hr). Tuber viability was reduced when temperatures > 45C. Yellow nutsedge tubers were more sensitive (required shorter duration of exposure to reduce viability) to 45, 50, and 55C than purple nutsedge. Tuber sensitivity to 60C was similar for both nutsedges. With sufficient durations of exposure, both purple and yellow nutsedge tubers were killed at temperatures > 50C. While there is a significant effect of heat and duration of exposure on nutsedge tuber viability, application of these data to field situations may be limited using present technology. Coupled with the difficulty in adequately increasing soil temperature, the distribution of nutsedge tubers in the soil profile poses a significant obstacle to the success of solarization in controlling nutsedge. Technical Abstract: Methyl bromide, the foundation for vegetable pest management, is suspected to contribute to ozone depletion and its use will cease in 2005. One proposed alternative is solarization. The efficacy of solarization is dependent upon temperature and duration of exposure. This study was conducted to determine the relationship between temperature and duration of exposure on purple and yellow nutsedge tuber viability. Tubers were exposed to temperatures ranging from 35 to 65C in 5C increments, for 12 durations ranging from 0 to 256 hr. Viability of treated tubers was evaluated 28 d after treatment. Tuber viability was reduced when temperatures > 45C (113F). Yellow nutsedge tubers were more sensitive (required shorter duration of exposure to reduce viability) to 45C (113F), 50C (122F), and 55C (131F) than purple nutsedge. Tuber sensitivity to 60C (140F) was similar for both nutsedges. With sufficient durations of exposure, both purple and yellow nutsedge tubers were killed at temperatures > 50C (122F). While there is a significant effect of heat and duration of exposure on nutsedge tuber viability, application of these data to field situations may be limited using present technology. Coupled with the difficulty in adequately increasing soil temperature, the distribution of nutsedge tubers in the soil profile poses a significant obstacle to the success of solarization in controlling nutsedge. |
