Control of Yellow Nutsedge(Cyperus esculentus)and Other Weeds Before Summer Planting of Alfalfa(Medicago sativa)

Abstract

After land was plowed in the spring and prepared for planting, yellow nutsedge(Cyperus esculentusL.) was allowed to develop to heights of 10 to 12 and 20 to 25 cm. Either glyphosate [N-(phosphonomethyl)glycine] or paraquat (1,1′-dimethyl-4,4′-bipyridinium ion) was applied to emerged yellow nutsedge and other annual weeds at rates of 0.5, 1, 2, and 4 kg/ha. Half of the plots were double-disked 3 days after herbicide applications, and then all plots were planted with alfalfa(Medicago sativaL. ‘Cayuga’). Disking alone and application of glyphosate or paraquat alone did not satisfactorily control all weeds. However, the combination of a herbicide and disking controlled weeds enough to allow excellent establishment of alfalfa. In the year after establishment, the first cutting yields from the better combination treatments ranged from 3000 to 4400 kg/ha, which is normal for mid- to late-summer plantings in the region. Glyphosate was better than paraquat for control of grass weeds. Paraquat approached glyphosate in effectiveness when a supplemental disking treatment was added. Disking was as effective as the herbicide treatments for control of yellow nutsedge but not for control of broadleaf or annual grass weeds.

Population dynamics of yellow nutsedge (Cyperus esculentus) in cropping systems in the southeastern coastal plain

“…Without competition from a crop, yellow nutsedge populations increased, even under intensive weed management in fallow areas using shallow tillage and glyphosate [N-(phosphonomethyl) glycine]. The inability to GA, 1990GA, -1994 Time of Rate application (kg ha-1) Chemical name control yellow nutsedge in fallow plots contradicts previous studies that showed reductions in yellow nutsedge densities with frequent shallow tillage Linscott et al 1978;Stoller et al 1972;Thomas 1969;Thullen and Keeley 1975). Thullen and Keeley (1975) depleted yellow nutsedge tuber carbohydrate reserves by tilling at 4-wk intervals, whereas the soil was tilled in our study at 2-mo intervals during the growing season.…”