Thousands of farm workers resumed the strikes that left two people dead last year. Pictures: Denzil Maregele/Foto24

Motorists were forced to avoid the N1 as protesters threw stones at passing cars.

A car belonging to a newspaper group was set alight but no one was injured.

Riot police were deployed to contain the situation. Lieutenant Colonel Andre Traut said about 50 people had been arrested.

Police retaliated with rubber bullets when striking workers threw rocks at officers.

In Wolseley, strikers turned away buses and trucks to impede non-striking workers from reaching the farms.

Labour federation Cosatu called for strikes to resume when negotiations with Agri-SA and government failed.

Farmers in the Hex River Valley hired private security to protect their property.

Protesters barricaded roads with burning tyres and rocks.