COVER CROPS in South African Vineyards

CHAPTER 5 WEED CONTROL

certain legumes did largely or entirely suppress weeds in some years, it can be seen that the results were not consistent. The legumes were also tested with full-surface chemical weed control starting in November. In general, weed stands were greater with this strategy than when weed control was started in August.

3,00

No cover crop Grazing vetch Faba bean Paraggio medic

2,50

Kelson snail medic Woogenellup clover

2,00

1,50

1,00

0,50

0,00

1993

1994

1995

1996

1997

1998

2001

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.

Year

Dry-matter production of weeds in tonnes per hectare FIGURE 5.28. Dry-matter production of summer-growing weeds in legume cover-crop treat - ments compared to a control without a cover crop in the Coastal region. Full-surface chem - ical weed control was applied at grapevine bud-break. Adapted from Fourie et al (2006). These trials in the Coastal region demonstrated that both grasses and legumes can contribute to weed management when combined with full-surface chemical weed control from grapevine bud-break.The use of winter-growing grasses and legumes as cover crops can help to reduce the use of herbicides. In addition, cover crops were effective irrespective of rainfall or irrigation system. Weed succession and dominance Every site has a unique weed population.This population will respond to weed management practices with changes in the relative abundance of different species.Two studies on different sites in the Coastal region examined weed succession and dominance. Plaisir de Merle A study at Plaisir de Merle looked at the species composition of weeds in a non-irrigated vineyard over a period of six years.The effects of cover crops

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