Population of nematodes in soils under banana, cv. Poyo, in the Ivory Coast : 4. Seasonal dynamics of populations in organic soil

Abstract

SUMMAKY The dynamics of nematode populations of bananas have been monitored during two vegetative cycles on two sites located on minera1 soil (gravelly sandy Clay soil and silty loam soil) in the banana producing area of the Ivory Coast. On this soil type the main endoparasitic nematodes which occur in the soil and in the roots are the burrowing nematode Radopholus similis, the spiral nematode Helicotylenchus multicinctus and on one site, Pratylenchus coffeae. In these conditions of soil type, fluctuations of R. similis in soil and roots or cortical part of the corm are a resultant of several factors such as the physiology of the renovation of the root system, the climate with respect to soil moisture, and the competition with the nematode species, making it the primary root invader. On this soil type, root infestation by H. multicinctus generally takes place after infestation by R. similis. This study also confrms that populations of both R. similis and P. coffeae, which occupy the same ecological niche, build up during the dry season and decrease with increasing rainfall, whereas H. multicinctus, Hoplolaimus pararobustus and Cephalenchus emarginatus show the reverse trend. In summary al1 the factors, endogenous or exogenous like the cultural practise of pruning, which favour new root emergence on banana plants contribute to the build up of R. similis population in the root system.