COVER CROPS in South African Vineyards

COVER CROPS IN SOUTH AFRICAN VINEYARDS

The average dry-matter production of winter- growing weeds is shown in Figure 5.25. Results demonstrated that both Overberg and Saia oats could reduce the weed stand by more than 90%, and that rye suppressed weeds by 76%. Legumes were less effective, but still reduced weeds by at least 50%.

BOTH OVERBERG AND SAIA OATS COULD REDUCE THE WINTER-GROWING WEED STAND BY MORE THAN 90% IN TRIALS IN THE COASTAL REGION.

No cover crop Paraggio medic Faba bean

1,83

0,91

0,86

Woogenellup clover Kelson snail medic Grazing vetch Henog rye

0,80

0,73 0,73

0,45

Saia black oats Overberg oats

0,13

0,06

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 5.25. Dry-matter production of winter-growing weeds in cover-crop treatments and a control without a cover crop in full-surface irrigated vineyards at the ARC Infruitec-Niet - voorbij in the Coastal region. Adapted from Fourie et al (2006). Trials focussing on cover crops with biofumigation properties were conducted in a drip-irrigated vineyard at Blaauwklippen over a period of five years.The cover crops were sown annually, and full-surface chemical weed control was applied from grapevine bud-break. The average dry-matter production of winter-growing weeds is shown in Figure 5.26. It can be seen that the weed stands were significantly greater in the control which had no cover crop. Cover crops reduced the average dry- matter production of weeds by at least 79%.

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