Competition between perennial ryegrass (Lolium perenne L. `Manhattan II') sod and wine grapes (Vitis vinifera L. `Chardonnay') for mineral nutrients was investigated with three methods of vineyard floor vegetation management (bare floor, mowed, and unmowed sod) and three rates of urea application (0, 137, and 274 kg N/ha). Sod decreased N concentration of grape leaves in both 1986 and 1987; Fe concentration in 1986; and S, Ca, B, and Mn in 1987. Sod also reduced total content of all measured nutrients in grape leaves. Mowing did not alleviate this reduction in leaf nutrient content. A high rate of urea (274 kg N/ha) compensated for N reduction in grape leaves caused by sod competition. Chemical names used: 2-[1-(ethoxyimino) butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2 -cyclohexen-1-one (sethoxydim); N,N-diethyl-2-(1-naphthalenyloxy)propanamide (napropamide).
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