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Title: Impact of elevated CO2 levels on control of purple and yellow nutsedge with glyphosate and halosulfuron

item MARBLE, S - University Of Florida
item Prior, Stephen - Steve
item Runion, George
item Torbert, Henry - Allen

Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 1/5/2015
Publication Date: 1/5/2015
Citation: Marble, S.C., Prior, S.A., Runion, G.B., Torbert III, H.A. 2015. Impact of elevated CO2 levels on control of purple and yellow nutsedge with glyphosate and halosulfuron [Abstract]. Proceedings of the Northeastern Weed Science Society. 69:26.

Interpretive Summary:

Technical Abstract: Atmospheric concentrations of carbon dioxide (CO2) have been steadily rising each year and are expected to continue increasing in the future which could have a significant impact on agricultural production. Previous research has shown that elevated CO2 increases the growth and yield of most plant species. Although many crops may benefit from increasing levels of CO2 in terms of growth and yield, the growth and distribution of many weed species is also likely to increase, as is the occurrence of herbicide resistant weed biotypes. There is now concern that global climate change could reduce the effectiveness of herbicides at current label rates. An experiment was conducted during the summer of 2012 to determine if labeled rates of glyphosate (RoundUp Pro®) and halosulfuron (SedgeHammer®) would provide effective control of purple nutsedge (Cyperus rotundus L.) and yellow nutsedge (Cyperus esculentus L.) in an enriched CO2 environment. Tubers of yellow and purple nutsedge were grown in 3.0 L containers in either ambient or elevated (ambient + 200 µmol mol-1) CO2 in open-top chambers and treated with 0.5×, 1.0× or 1.5× the labeled rate of each product and a tank mix of each product at the specified rates. Both species of nutsedge had a positive growth response when exposed to elevated CO2, as purple nutsedge increased shoot and root dry weights and tuber counts by 27%, 25%, and 25%, respectively, in comparison to plants grown at ambient levels. Yellow nutsedge had a greater response to elevated CO2, increasing shoot, root, and tuber dry weights by 40%, 51%, and 100%, respectively, and tuber counts by 128%. Few differences were observed in terms of herbicide efficacy, and by 3 weeks after treatment provided over 90% control regardless of herbicide or tank-mix, rate, or CO2 concentration. Based on the results of this study, it appears that although both weed species will increase growth and reproductive capability, the efficacy of halosulfuron or glyphosate will not be impacted by increasing atmospheric CO2 levels. Both products provided adequate control of both nutsedge species when applied prior to the flowering stage. It is unclear how the efficacy of these active ingredients would have been impacted by delaying applications until either species was closer to or had reached maturity.