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  • Author or Editor: Garvin Crabtree x
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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).

Free access

Abstract

Plants of red-osier dogwood (Cornus sericea L.) treated with 2,4-dichlorophenoxy-acetic acid (2,4-D) or l,1’-dimethyl-4,4’-bipyridium ion (paraquat) after reaching vegetative maturity were much less affected by the herbicides than plants treated earlier. Data support the hypothesis that vegetative maturity is a distinct physiological stage in the development of woody plants, and that inconsistencies in herbicide efficacy can, in part, be explained by this phenomenon.

Open Access

Abstract

In a greenhouse experiment, lettuce (Lactuca sativa L.) showed considerable tolerance to N-(l,l-dimethylpropynyl)-3,5-dichlorobenzamide (pronamide) with a safety factor greater than 2 × compared to susceptible weeds. The crop and weed tolerance was greater in a silty clay loam and a muck soil than in a sandy soil. Barnyardgrass [Echinochloa crus-galli (L.) Beau v.] was more susceptible to pronamide than redroot pigweed (Amaranthus retroflexus L.) and wild turnip (Brassica campestris L.).

Open Access