Geneva - War-torn South Sudan could become the scene of the worst famine catastrophe in Africa in decades without more aid and a ceasefire to let farmers reach their fields, the UN warned on Thursday. #8220;If we miss the planting season, there will be a catastrophic decline in food security,#8221; Toby Lanzer, the UN's top aid official in the country, told reporters in Geneva. #8220;What will strike...