The event, the Great North Rally, starts in Tzaneen today (Friday).
Burger has been hospitalised with a bout of pneumonia, which has forced his withdrawal from the event.
"It is terribly disappointing to have to withdraw, but I have been ill for over a week and don?t know when I will be released from hospital," explained Burger.
"It is especially disappointing as this was to be my last national championship rally and, after our win on the last round, I was looking forward to going for another win.
"It's not the ideal way to retire, but that's life. My priority now is just to get well."