TABLE CONTENTS

Nematode Diversity under Commercial Banana Production
Pattison, A. (1), J. Cobon (2), M. Araya (3), L. Pocasangre (4), F. Rosales (4) & R. Sikora
(5)
(1) Queensland Department of Primary Industries and Fisheries; (2) Centre for Wet Tropics, South Johnstone,
Queensland 4859; (2) 80 Meiers Rd, Indooroopilly, Queensland 4068; (3) Corporación Bananera Nacional
APDO. 390-7210 Guapiles, Costa Rica; (4) Bioversity International, CATIE, Turrialba 7170 Costa Rica; (5)
Institut fuer Pflanzenkrankeiten, University of Bonn, Nussallee 9, 53115 Bonn, Germany
Radopholus similis remains an economic constraint to sustainable banana production for
many tropical countries. Nevertheless, R. similis is not an economic problem on some
banana farms although the nematode is present. The mechanisms of why some soils become
suppressive to R. similis may be uncovered with a better understanding of the soil ecology.
Soil nematodes and their assemblages have been used as an indicator of soil ecological
processes, which may help to develop more sustainable banana production systems.
Investigations were made in commercial banana production at two different locations,
Australia and Costa Rica.
A survey conducted in Australia comparing nematode assemblages under banana production
with neighbouring forest or pasture soils found that banana production had a significantly
lower nematode diversity (Shannon-Weiner index) and greater proportion of plant-parasitic
nematodes relative to forest and pastures sites. Further studies in a replicated field
experiment found diversity of soil nematodes was significantly lower when bare soil was
maintained in the interplant space compared to vegetated areas. Furthermore, changes in soil
labile C and soil NO 3 -N levels were correlated with increasing nematode diversity. This
finding was confirmed in a survey of 10 commercial banana farms.
Simultaneously, poor root growth and decreasing production was being experienced in
banana plantations in Costa Rica. A survey of 21 commercial banana plantations found that
the diversity of soil nematodes was at a maximum on farms with a soil pH of 6. Furthermore,
when in vitro banana plantlets were grown in soil collected from the farms and inoculated
with R. similis, fewer nematodes were recovered from the roots of plants grown in soil with a
neutral pH.
To maintain diversity of soil organisms in banana production, the management of soil carbon,
nitrogen, pH and mix of plant species was found to be important. However, investigations at
regional levels were needed as different constraints to nematode diversity develop under
different conditions.
Acknowledgements
Horticulture Australia Limited and Growcom provided funding for the work in Australia
under project FR02025 and Bioversity International and CORBANA assisted with the work
conducted in Costa Rica.
5 th International Congress of Nematology, 2008 5