A five-year trial (2009 to 2013) was executed in a drip-irrigated seven-year-old Shiraz/101-14 Mgt
vineyard established on a sandy to sandy clay loam soil at Blaauwklippen Farm (33°58’S, 18°50’E) near
Stellenbosch, South Africa. Fourteen treatments, consisting of two management practices applied to five
cover crop species, as well as winter-growing weeds (no cover crop) and winter-growing weeds (no cover
crop) with nematicide applied in the vine row, were applied. The weeds and cover crop species were either
controlled chemically (CC) or mechanically (MC) during grapevine bud break, followed by full-surface
chemical control during berry set (for both CC and MC treatments). Rhynchelytrum repens (Natal redtop)
dominated the post-harvest pre-treatment weed spectrum in all the treatments except Eruca sativa
cv. Nemat (Nemat) (MC). This species lost its post-harvest dominance from 2010 onwards. It seems that
the relatively low summer rainfall during the 2010/2011 season allowed Anagallis arvensis to appear in
April 2011 and dominate some of the treatments, which coincided with the disappearance of Cynodon
dactylon (common couch) and Polygonum aviculare (prostrate knotweed). Digitaria sanguinalis, common
couch and prostrate knotweed seemed to establish better during late summer where MC was applied. The
pre-treatment average post-harvest weed stand of 5.53 t/ha was reduced to 0.53 t/ha within one season,
illustrating the benefit of full-surface chemical weed control applied during grapevine berry set.
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