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Sanguankeo PP & León RG (2011). Weed management practices determine plant and arthropod diversity and seed predation in vineyards. Weed Research51, 404–412. Summary In the Central Coast of California, USA, wine grape growers are making efforts to identify weed control practices that preserve biodiversity in their vineyards while maintaining yields. A field study was conducted in Paso Robles, California in 2006 and 2007 evaluating the effect on plant and ground dwelling arthropod communities of five weed control practices conducted under the vines within the row (berm): (i) flumioxazin, (ii) simazine, (iii) cultivation, (iv) cover crop and (v) untreated control. The cover crop, cultivation and untreated control had 4–50 times higher plant density and more than 15 times higher plant diversity compared with the herbicide treatments. The arthropod activity‐density differed among treatments only in 2007, being higher in the cover crop and untreated control. There was a positive relationship between plant and arthropod diversity (r2 = 0.42, P = 0.02 in 2006; r2 = 0.64, P < 0.001 in 2007). Laboratory seed predation tests of the two most frequently captured carabid beetles, Calathus ruficollis and Tanystoma maculicolle, indicated they predated more of the common weed species Brassica nigra and Capsella bursa‐pastoris, than other weed species tested. Under field conditions, treatments with higher plant diversity and density favoured arthropod seed predation of these weeds. Predation rates were 20–40% in the cover crop and untreated control, double that observed in the herbicide treatments. The cultivation treatment balanced the benefits of promoting diversity while minimising yield reductions caused by weed competition. The results indicate that weed management practices that promote higher plant diversity and density have the potential to yield ecological benefits within vineyards, for example, enhancing the activity of beneficial organisms.

The need for reducing costs and making grape production more sustainable has prompted the search for alternative weed control practices that optimize production while maintaining profits. For this reason, it is imperative to understand how different weed management practices modify vine–weed interactions. In the present study, we evaluated the effect on weed growth and Zinfandel grapevine growth and production of five weed control practices: (1) flumioxazin, (2) simazine, (3) cultivation, (4) cover crop, and (5) untreated control. The herbicide treatments had the lowest weed biomass, followed by the cultivation, being approximately 10 and 2 times lower than the weed biomass of either the cover crop or untreated control treatments, respectively. However, the differences in grape yield were not as evident. In 2006, a rainy year, the herbicides and cultivation treatments did not differ in grape yield, but the cover crop and untreated control had a reduction of approximately 20% compared with the other treatments. In 2007, a dry year, in comparison to the herbicide treatments, the grape yield reductions of cultivation were around 22%, and those of the cover crop and untreated control were around 48%. Although the cover crop reduced grape yield, it suppressed weed species considered important, such as horseweed, panicle willowherb, scarlet pimpernel, and sowthistle. Also, it was concluded that vines can tolerate a certain amount of weed competition, and that properly timed postemergence control actions (e.g., cultivation or POST herbicides) could provide the necessary level of control to obtain the desired yields. However, under limited soil moisture conditions, the use of PRE herbicides could prove important to maintain vine yield and vigor.

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