Vegetative compatibility groups within Kenyan populations of Fusarium oxysporum f. sp. cubense

Fusarium wilt of banana, caused by Fusarium oxysporum forma specialis cubense (Foc), is causing significant losses for small-scale holders in Kenya. The affected cultivars include 'Muraru' (AA?), 'Wang'ae' (AB),'Gros Michel' (AAA), and 'Bluggoe' (ABB). Vegetative compatibility studies involving 135 isolates of Foc have been carried out and compatibility has been recorded with testers from five existing vegetative compatibility groups (VCGs): VCG 01212, VCG 0124, VCG 0125, VCG 0128 and VCG 01220. Some isolates did not show anastomosis with tester strains and may belong to previously unrecognised VCGs. In many cases the isolates showed bridging reactions and were compatible with two or more testers from the 0124/5/8/20 complex. This complex represents a single clonal lineage of Foc and was the predominant and most widespread population in the country. The only other VCG found (01212) forms a second clonal lineage and may be cultivar specific. The distribution of these populations in Kenyan smallholder banana plantations has been determined and will assist in monitoring the occurrence of new strains.