The controversial song is riddled with profanities used to describe the history of farmworkers.
While Cosatu welcomed the pay increase, it said wages were still far too low.
Union to investigate allegations of racism and unfair treatment.
Striking farmworkers have prevented nurses from reporting for duty in the Western Cape.
There are reports that striking farmworkers are throwing stones in Clanwilliam and Riviersonderend.
Police moved swiftly to arrest violent protesters taking part in the widespread industrial action.