Polyethylene mulch is an effective component of weed management in vegetable production. However, nutsedges are persistent and proliferate in these systems. Greenhouse studies evaluated the growth and tuber production of purple nutsedge and yellow nutsedge grown in pots covered with black-opaque polyethylene mulch, clear-colorless polyethylene mulch, or nonmulched. Single, presprouted nutsedge tubers were planted and growth evaluated over 16 wk. Relative to the nonmulched, yellow nutsedge shoot production was reduced 46 and 72% by black and clear mulch, respectively. The number of yellow nutsedge shoots that pierced and emerged through black and clear mulches was reduced 96% relative to emerged shoots in the nonmulched control. Yellow nutsedge in the nonmulched produced 366 tubers per initial tuber, whereas tuber production was reduced 49 to 51% in black and clear mulch. Growth of purple nutsedge shoots and tubers in black polyethylene mulch was similar to the nonmulched. Clear polyethylene reduced purple nutsedge tuber biomass relative to nonmulched, but clear mulch was similar to black mulch in nearly all measured variables. Without mulch, yellow nutsedge produced more shoots, shoot biomass, tubers, tuber biomass, and root biomass than purple nutsedge. However, growth of yellow nutsedge was hindered by polyethylene mulch, whereas differences in purple nutsedge growth among mulches could not be detected. The relative insensitivity of purple nutsedge and sensitivity of yellow nutsedge growth to the physical mulch barrier could lead to a shift in nutsedge species composition in mulched vegetable production.

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