Pathogenicity and damage potential of five species of plant-parasitic nematodes on plantain (Musa spp., AAB genome) cv. Agbagba

The pathogenicity of five plant-parasitic nematode species, Radopholus similis, Pratylenchus coffeae, Helicotylenchus multicinctus, Hoplolaimus pararobustus and Meloidogyne spp., commonly recorded from banana and plantain in West and Central Africa, was assessed on plantain (Musa spp., AAB genome) cv. Agbagba in Nigeria. The pest status of H. pararobustus was demonstrated for the first time in addition to H. multicinctus, while the importance of P. coffeae and R. similis was further confirmed. In addition, the study further demonstrated the contribution of nematodes to weakened pseudostems (stems) and stem snapping during periods of low water availability, in the absence of weevil damage. Through a series of experiments, the nematode damage potential was evaluated in 20 l pots, 70 l microplots (halved oil drums) and a field experiment over four crop cycles. In pots only a combination of four species (without H. pararobustus) led to greater root necrosis than the non-inoculated control, while R. similis reduced root mass. In microplots most crop growth parameters were similar across treatments, except root necrosis, which was higher for all nematode treatments than on control plants and more severe on P. coffeae roots than for other nematode species. In the field trial heavy storms disrupted data collection. Plant stem snapping, however, was greater for all nematode treatments compared with controls. Nematode damage indices such as feeder root health and root necrosis were higher in all nematode treatments and consistently so for R. similis and P. coffeae over the first two cropping cycles. Mean bunch weight of harvested plants was lower for all nematode treatments than controls; between 33.3% and 50.8%, even for first cycle mother plants, and consistently lower across crop cycles.