COVER CROPS in South African Vineyards

COVER CROPS IN SOUTH AFRICAN VINEYARDS

Breede River valley Trials in the Breede River valley were conducted at the ARC Infruitec-Niet- voorbij research farm near Robertson in theWestern Cape. Different cover crops were sown in vineyards as described in Vineyard trials in Chapter 3 (p56). Dry-matter production was measured for both the cover crops and the weeds over a period of 12 years. Winter-growing weeds Annual cover crops were sown each year in autumn. No cover crop was sown in the control. Full-surface chemical weed control was applied from just before grapevine bud-break to harvest. Dry-matter production of weeds in the cover-crop treatments was compared to that of weeds in the control. The average dry-matter production of weeds in the different treatments and controls is illustrated in Figure 5.22. It can be seen that the average winter-weed stand was significantly reduced in treatments in which a cover crop was established, except in the case of grazing vetch.

No cover crop

1,82

Dwarf fescue

0,59

Grazing vetch

0,88

Triticale + grazing vetch annual rotation

0,48

0,42

Triticale + grazing vetch two-yearly rotation

0,54

Rye + faba bean mix

0,19

Triticale

0,00 0,20 0,40 0,60 0,80 1,00 1,20 1,40 1,60 1,80 2,00 Dry matter of weeds in tonnes per hectare

FIGURE 5.22. Dry-matter production of winter-growing weeds in cover-crop treatments and a control without a cover crop in the Breede River valley. Adapted from Fourie (2010).

Triticale gave the best result, achieving a 90% reduction in the dry-matter production of winter-growing weeds. It may be recalled from Cover-Crop Selection in Chapter 3 (p46) that triticale produced more dry matter overall than the other cover crops at this site.

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