Two banana diseases spreading in Africa could hurt food supply for 30 million people on the continent who largely rely on the crop, an international agricultural research body has warned. The Consultative Group on International Agricultural Research (CGIAR) said the banana bunchy top viral disease has infected 45,000 hectares of bananas in Malawi alone and a survey done last year found it in 11 other countries. A serious attack of banana bunchy top causes all leaves to sprout from a plant's top, stunting its growth. The affected countries are in eastern, central and southern Africa. CGIAR said another study earlier this year found banana bacterial wilt disease in Ethiopia, Uganda, Rwanda, western Kenya, northwest Tanzania and north and South Kivu in the Democratic Republic of Congo.