Police fired rubber bullets at striking farm workers today in a province whose vineyards are vital to the wine industry.
The demonstrators set up barricades and threw stones at motorists and security forces. The authorities said 50 people were arrested.
Labour unrest was reported in several areas of Western Cape province, where similar protests last year also turned violent, causing at least two deaths.
Chaotic scenes unfolded in the town of Grabouw, where protesters, some carrying clubs, raced through the streets during clashes with riot police.
The protesters had sought to block roads in a campaign to raise wages and to prevent other farmhands going to work. They want daily wages more than doubled to R150 (£11).
Talks had failed to avert the strike, which affects vineyards, apple and other fruit farms.