The phase-out of methyl bromide requires alternative nutsedge management options in vegetable systems. Options that target tuber production, the primary means of reproduction, will be most beneficial. A study was conducted to evaluate the response of purple nutsedge and yellow nutsedge foliar growth and tuber production to a range of glyphosate rates. Glyphosate was applied at six rates between 0.41 and 2.57 kg ae ha⁻¹ to 5-wk-old nutsedge plants with multiple shoots. The rate of glyphosate needed to reduce growth 50% (I₅₀) was similar for purple nutsedge foliar growth (0.58 kg ha⁻¹) and tuber biomass (0.55 kg ha⁻¹). In contrast, I₅₀ for yellow nutsedge foliar growth was 0.73 kg ha⁻¹, which was greater than the I₅₀ for tuber biomass (0.41 kg ha⁻¹). First-order tubers, those directly attached to the initial tuber, had an I₅₀ of 0.70 and 0.44 kg ha⁻¹ of glyphosate for purple nutsedge and yellow nutsedge tuber biomass, respectively. For all higher-order tubers, I₅₀ values ranged from 0.29 to 0.60 and 0.14 to 0.30 kg ha⁻¹ of glyphosate for purple nutsedge and yellow nutsedge tuber biomass, respectively. Glyphosate at 0.74 kg ha⁻¹ prevented fourth-order purple nutsedge and third-order yellow nutsedge tuber production (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). Effective nutsedge management options will require consistent control between spring and autumn crops. Glyphosate is economical, poses no herbicide carryover issues to vegetables, and minimizes nutsedge tuber production; therefore, it is a suitable candidate to manage nutsedges.

Nomenclature: Glyphosate; purple nutsedge, Cyperus rotundus L. CYPRO; yellow nutsedge, Cyperus esculentus L. CYPES.