South African farmers have been hit by days of unrest and looting as trucks carrying produce are prevented from delivering to markets.

The country's citrus exports through the port of Durban have been halted after violence erupted in the KwaZulu Natal and Gauteng regions.

Crowds have this week clashed with police and ransacked shopping malls, with dozens reported killed as grievances unleashed by last week's jailing of former president Jacob Zuma boiled over into the worst violence in years. 

Citrus Growers Association Chief Executive Justin Chadwick said trucks carrying citrus have been unable to use the main arterial roads to the Durban port, where more than half of the citrus is exported.

He also said that harvesting and packing could not be stopped since producers would then face losing their crops, Farmers Weekly reported. Instead, fruit was being palletised and kept in cold storage on farms until the roads were safe again.

“Most cold storage facilities in the [Port of Durban] have closed down, as have the fresh produce facilities. People can’t get to work so there is no one there to operate the ports," he was quoted as saying.

Chadwick expressed concern about the ripple effect of the disruption in trade.

“Even if the unrest ends now, we will continue to feel the effects for some time to come as the sudden flow of produce will cause bottlenecks at the ports," he said.

He added that a sudden glut of citrus on the market once supplies were flowing again would negatively affect prices.

“If you lose a sales day you don’t gain it later. We will see large amounts of citrus coming onto the market at once and this will impact returns.”

South Africa in May forecast citrus exports in 2021 to set another consecutive record, driven in large part by late mandarins. The CGA said estimates are for 158.7 million cartons, up from 146 million last year.