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ARS Home » Southeast Area » Tifton, Georgia » Crop Protection and Management Research » Research » Publications at this Location » Publication #197452
Title: Glyphosate Hinders Purple Nutsedge (Cyperus rotundus) and Yellow Nutsedge (Cyperus esculentus) Tuber Production

Author
item Webster, Theodore
item GREY, T - UNIV. OF GA, TIFTON,GA
item DAVIS, J - UNIV. OF GA, GRIFFIN,GA
item CULPEPPER, A - UNIV. OF GA, TIFTON,GA

Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/28/2008
Publication Date: 10/1/2008
Citation: Webster, T.M., Grey, T.L., Davis, J.W., Culpepper, A.S. 2008. Glyphosate hinders purple nutsedge (Cyperus rotundus) and yellow nutsedge (Cyperus esculentus) tuber production. Weed Science. 56(5):735-742.

Interpretive Summary: Purple and yellow nutsedge are among the most troublesome weeds of cucurbit and fruiting vegetable production in the Southeast US. Methyl bromide has been used to effectively manage this pest. However, with the phase-out of methyl bromide, nutsedge control in these systems will necessitate alternative options that will manage the weed and its tubers, the primary means of nutsedge reproduction. Glyphosate can be applied between the rows of many vegetable crops and can be applied to nutsedge emerging through mulch prior to crop planting and after crop harvest is complete. Glyphosate at 0.41, 0.59, 0.74, 0.95, 1.23, and 2.57 kg ha-1 reduced purple nutsedge tuber biomass to 80, 49, 35, 7, 8, and 20% of the nontreated control and yellow nutsedge tuber biomass to 49, 30, 19, 15, 16, and 10% of the nontreated control, respectively. Relative to the nontreated control, first-order (first generation produced from the original tuber) tuber biomass was reduced by glyphosate at 0.41 and 0.95 kg ha-1 for yellow and purple nutsedge, respectively. Glyphosate at 0.74 kg ha-1 prevented fourth-order purple nutsedge tuber production and third-order yellow nutsedge tuber production (the terminal tubers for yellow nutsedge). Fifth- and sixth-order purple nutsedge tuber production was eliminated by the lowest tested rate of glyphosate (0.41 kg ha-1). Because glyphosate is economical and poses no herbicide carryover issues to vegetables, it will be a primary tool used to manage nutsedges.

Technical Abstract: Purple and yellow nutsedge are among the most troublesome weeds of cucurbit and fruiting vegetable production in the Southeast US. The phase-out of methyl bromide will necessitate alternative management options that target tubers, the primary means of nutsedge reproduction. Greenhouse studies were conducted to evaluate the impact of different rates of glyphosate on purple and yellow nutsedge growth and tuber production. Glyphosate was applied at seven rates ranging from 0 to 2.57 kg ae ha-1. Glyphosate at 0.41, 0.59, 0.74, 0.95, 1.23, and 2.57 kg ha-1 reduced purple nutsedge tuber biomass to 80, 49, 35, 7, 8, and 20% of the nontreated control and yellow nutsedge tuber biomass to 49, 30, 19, 15, 16, and 10% of the nontreated control, respectively. Relative to the nontreated control, first-order (first generation produced from the original tuber) tuber biomass was reduced by glyphosate at 0.41 and 0.95 kg ha-1 for yellow and purple nutsedge, respectively. Glyphosate at 0.74 kg ha-1 prevented fourth-order purple nutsedge tuber production and third-order yellow nutsedge tuber production (the terminal tubers for yellow nutsedge). Fifth- and sixth-order purple nutsedge tuber production was eliminated by the lowest tested rate of glyphosate (0.41 kg ha-1). In spite of the characterization to the contrary, yellow nutsedge was documented to form short chains of tubers. Glyphosate poses no herbicide carryover issues to vegetables and will likely be a primary tool to manage nutsedges.