COVER CROPS in South African Vineyards

CHAPTER 3 COVER-CROP SELECTION

Creeping saltbush initially suppressed both the winter- and summer-growing weeds. However, during the final winter of the trials, creeping saltbush was overwhelmed by winter-growing weeds with an upright habit, such as the ryegrasses and ripgut brome, regardless of irrigation. This trial showed that creeping saltbush is not a sustainable cover-crop option over the medium-term, because of the build-up of erect-growing grass weeds when no herbicide is applied from grapevine bud-break to harvest.

FIGURE 3.28. Creeping saltbush ( Atriplex semibaccata ). (Photo: ARC Infruitec-Nietvoorbij).

Fynbos and renosterveld species Trials of indigenous fynbos and renosterveld species as cover crops were conducted over four seasons in vineyards at Boschendal farm in the Coastal region.The hope was that growing these indigenous species in vineyards could expand their habitat and promote their conservation. The indigenous annual-species mix was evaluated on its own, as well as in combination with pink serradella, and in combination with Paraggio bur medic. The indigenous perennial mix was evaluated on its own, as was the indigenous succulent mix. Lastly, a mix of all the indigenous annuals, perennials, and succulents was assessed.

Seeds were collected from the wild and sown inApril. Rainfall was supplemented with irrigation when necessary. None of the mixtures established successfully, even though grass weeds were con- trolled with a grass-specific post-emergence herbi- cide in early June.Their use as cover crops cannot therefore be recommended.

INDIGENOUS FYNBOS AND

RENOSTERVELD SPECIES WERE UNSUCCESSFUL AS COVER CROPS IN THESE TRIALS.

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