The root-invading nematode-fungus complex of plantains and bananas : A review

Since the outset of their economic expansion and up to now, Plantains and Bananas (Musa spp.) have had to face simultaneously with diverse root-colonising pathogens among which vascular and root rot fungi as well as communities of plant-parasitic nematodes often act as a complex. Depending at once on the occurrence of adequate inoculum, the nature and incidence of this root pathogenic complex (RPC) vary strongly, as a consequence of its interactions with the cropping system, the soil and climate conditions. In some situations, this RPC can thus be dominated by the soilborne fungus Fusarium oxysporum f. sp. cubense which is responsible for the much-dreaded Panama disease (also called Fusarium Wilt). In other conditions, the root system of plantains and bananas is mainly altered by endoparasitic nematodes among which Pratylenchus spp., Radopholus similis, Helicotylenchus multicinctus and Meloidogyne spp. are frequently prevailing. In this second case, the detrimental action of plant-feeding nematodes can be completed or strengthened by root rot fungi, many contributing as necrosis extensors but others as Cylindrocladium spp. (teleomorph Calonectria spp.) operating as true primary pathogens. The purpose of the present paper is to review the biology, the diversity, and the ecology of these pathogens. Some attention is also given to the possible interactions that can take place within this complex, but also outside it, as the relations RPC - non-pathogen organisms, such as root endophytes, are also treated. Achieved or prospective management for the control of these soilborne pathogens is discussed, including cultural tactics, biological control and breeding. (Texte intégral)