All bananas cultivated for export are Cavendish cultivars and are considered to be very susceptible to both the burrowing nematode Radopholus similis and the lesion nematode Pratylenchus coffeae. Twelve cultivars of Musa spp. genome AAA cv. Grande Naine from mass field selections in Martinique and Guadeloupe were cloned and micro-propagated in tissue culture. Resistance of these sibling cultivars to nematodes was tested in two growth chamber trials and in one 2-year field trial in a former banana field heavily infested with nematodes and without control methods (no guying or nematicide applications). The field trial also included a new synthetic hybrid FB920 that has tolerance to yellow and black Sigatoka and partial resistance to nematodes. Trends were similar in growth chamber and field trials in that all Cavendish cultivars were susceptible to nematode species, although some differences in susceptibility were detected, and in particular roots of the selected cultivar MA13 contained fewer R. similis than the most susceptible cultivars of Cavendish (cvs. Petite name, Poyo and L93). Cultivar MA13 was also less susceptible than most commercial cultivars to P. coffeae in the growth chamber trials, and a similar but insignificant trend was documented in the field trial. In the field trial, all cultivars experienced severe damage (lengthening of vegetative and reproductive stages, uprooting and reduced yield), which was attributed to the high level of nematode infestation. Although tolerance to nematodes in the field trial was greater for the synthetic new hybrid FB920 than for the Cavendish cultivars, FB920 produces small bunches and tall plants that will prevent its development as a banana for export (but will not prevent its production by small holders). In summary, this study shows that there is useful variation in tolerance to R. similis and P. coffeae among sibling Cavendish cultivars and that growth chamber trials with in vitro-cultivated plants are useful for screening for such susceptibility. (C) 2012 Elsevier Ltd. All rights reserved.

21 tant les bananiers est composée d’endoparasites migratoires, Radopholus similis (Cobb, 1893) Thorne, 1949, et Pratylenchus coffeae Goodey, 1951 ; d’endoparasites Helicotylenchus multicinctus (Cobb, 1893) Sher, 1961,et Hoplolaimus seinhorsti Luc, 1958 ; et de sédentaires endoparasites Meloidogyne spp. and Rotylenchulus reniformis Linford & Oliviera, 1940. Alors que toutes ces espèces exploitent la même ressource (les racines des plantes) et sont capables de parasiter une grande diversité de plantes hôtes , elles différent dans leurs traits d’histoire de vie (sédentaire, migratoires) et leur stratégie reproductive (parthogénétique, amphimictique). Outre le bananier, ces différentes espèces sont capables d’exploiter un certain nombre d’adventices présentes dans les agro-écosystèmes bananiers. Alors que R. similis et H. multicinctus sont très associés à ces agro-écosystèmes bananiers, les quatre autres espèces sont trouvées dans la plupart des autres écosystèmes incluant ceux non cultivés . Dans cette étude, nous avons testé l’hypothèse que la communauté de nématode phytophage est structurée par les plantes hôtes.

A mutant of 'Grande Naine', the cultivar MAI3 (Mt/sa AAA, Cavendish subgroup) has been selected in the field in Martinique for its good horticultural characteristics (hardiness, bunch conformation, productivity...). This peculiar cultivar always demonstrated significant lower susceptibilities to the bUlTOwing nematode Radopholus similis and to the lesion nematode Pratylenchus coffeae. In addition, the cv MAl3 exhibited singularly redder pseudostem as compared to others Cavendish clones. On the basis ofthese observations, we selected in field conditions some others 'coloured' mutants among different banana subgroups; cv MAl3_Green (Musa AAA, Cavendish subgroup), cv dwarfMossi_Green (Musa AAA, Red subgroup) and cvs 920_Red, 920_Green and 921_Red (Musa AAA, CIRAD hybrids). The susceptibility to nematodes of classic cultivars and associated mutants was evaluated under controlled conditions in a growth chamber on Andosol (volcanic ash soils representative of the French West Indies banana production area), at 24-28°C and 80% RH. Forty-five days after inoculation of each banana clone with 400 R. similis or P. coffeae per plant, the entire root system was carefully collected and weighted, and nematodes were extracted. In vitro micropropagation has no effect on the colour stability of the pseudostem. Reproductive factors and root infestations showed consistent trends, with an increase in R. similis root infestations for green mutants (up to 54%) and a decrease for red mutants (up to 61%) compared to classic cultivars. Surprisingly, the opposite consistent trend was observed for P. coffeae root infestations, with a decrease for green mutants (up to 43%) and an increase for red mutants (up to 76%) compared to classic cultivars. These results provide first evidence that colour criterion, representative of the anthocyanins content, could be a good and fairly simple indicator of nematode susceptibility in selection process. (Texte integral)

During a survey of the nematodes associated with weeds in banana fields in Martinique, 41 weed species in 37 genera from 20 plant families were collected to extract nematodes from the roots. Results of this survey showed that 24 weed species were hosts of Radopholus similis, 23 were hosts of Helicotylenchus spp., 13 were hosts of Pratylenchus spp., 13 were hosts of Hoplolaimus seinhorsti, 29 were hosts of Meloidogyne spp. and 24 were hosts of Rotylenchulus reniformis. The presence of the burrowing nematode was more consistently found within three families, the Euphorbiaceae, Poaceae and Solanaceae. In some weed species such as Caladium bicolor, Commelina diffusa, Echinochloa colona and Phenax sonneratii, the levels of nematodes recovered were similar to, or greater than the numbers recovered from Musa roots. These results clearly show that certain weeds can be significant reservoirs of plant parasitic nematodes including R. similis in banana fields. This information is crucial in devising appropriate nematode control measures for use with rotation crops or fallow before re-planting banana fields with nematode free planting material.

Depuis une dizaine d'annees, l'intensification de la filiere maraichere a la Martinique est marquee par l'essor des cultures sous abris. La connaissance des contraintes phytosanitaires d'origine tellurique des cultures maraicheres de plein champ a conduit a rechercher les bases necessaires pour assurer la perennite de ces cultures sous abris en pleine terre. Ce travail a ete realise par la methode du suivi multilocal d'exploitations. Apres 14 mois, l'inventaire du parasitisme tellurique a pu etre dresse. La nematofaune phytoparasite est dominee par Meloidogyne et Rotylenchulus; Meloldogyne constituant une contrainte majeure a la production sur deux des sites suivis. Le genre Rotylenchulus n'est par contre dominant que sur le site installe sur ferrisol. Du point de vue de la microflore, les champignons pathogenes et saprophytiques sont caracterises par des fluctuations importantes de leur frequence d'isolement : trois especes pathogenes potentielles sont les plus frequentes : Fusarium solani, Pythium splendens et Rhizictonia solani. Enfin d'un point de vue agronomique, les inconvenients de certains types de sol (ferrisol) et les repercussions de certaines techniques culturales sur le parasitisme sont apparus accentues en culture sous abri

SUMMARY Screening of fumigant and non fumigant nematicides was conducted on banana plants on the Ivory Coast between 1981 and 1984 on mineral and organic soils. The methodology used permitted separation of the effects on the growth from the effects on the harvest. This study also revealed the different components of nematode damages in banana plantations in the Ivory Coast : i) lengthening of the vegetative cycle without reduction of the total harvest; iil lengthening of the vegetative cycle and reduction of the total harvest; iii) reduction of the longevity of the plantation. These types of damages can be observed mixed in a same plantation with a severity in relation with the soil type. Nematode damage was more important on mineral soil than on organic soil. On organic soil, nematicidal and horticultural results from peat soil and Clay soil were very different, despite an apparent similar nematode community. Numerous varied relationships were found between nematode species in portion of the root system and horticultural parameters. In this study, al1 chemicals did not show an equal efficacy in reducing the nematode population, optimizing the vegetative growth and increasing the total harvest. In mineral soils, aldicarb gave the more consistent results, both from a nematological and horticultural point of view.

SUMMARY Three field experiments were conducted in the Ivory Coast to evaluate the efficacy of a new organo-phosphate nematicide, cadusafos (formerly ebufos, Rugby@), compared with three other non-fumigant nematicides for control of nematodes on bananas. The activity of cadusafos in controlling al1 nematode populations in these experiments was better than the other compounds even when used at a lower dosage (2 g a.i./plant). Analysis of horticultural measurements, including growth and harvest, clearly illustrated the damaging components occuring on bananas in the Ivory Coast : lengthening of the duration of phenological phases and reduction of the harvest. Application of cadusafos increased yield 15.6 % over treatment with aldicarb and 48.8 % over the non-treated control (cumulative results of three harvests). FWUME

SUMMARY Three field experiments were conducted in the Ivory Coast to evaluate the efficacy of a new organo-phosphate nematicide, cadusafos (formerly ebufos, Rugby@), compared with three other non-fumigant nematicides for control of nematodes on bananas. The activity of cadusafos in controlling al1 nematode populations in these experiments was better than the other compounds even when used at a lower dosage (2 g a.i./plant). Analysis of horticultural measurements, including growth and harvest, clearly illustrated the damaging components occuring on bananas in the Ivory Coast : lengthening of the duration of phenological phases and reduction of the harvest. Application of cadusafos increased yield 15.6 % over treatment with aldicarb and 48.8 % over the non-treated control (cumulative results of three harvests). FWUMÉ

SUMMARY The chemical treatment of banana cv. Poyo planting material by coating with one of the four systemic nematicide products : carbofuran, phenamiphos, isazophos and aldicarb, employed at 2 g per corm, or with a fumigant (dibromochloropropane) at 1.3 ml per corm, prevents rapid development of nematode populations (Radopholus similis, Hoplolaimus pararobustus and Cephalenchus emarginatus) after planting. The nematicidal activity lasts for about three to four months. The systemic nematicides controlled parasites by direct contact during their migration through the coating and in the soil after the dissolution of the products in it, or in roots by systemic effects. Al1 products, except dibromochloropropane, reduced the population levels, but their efficacies differed according to the nematode species. This trial also shows that population fluctuations of al1 nematode species depend on the climatic seasons : the parasite populations declined in the roots during the dry seasons.

SUMMARY The chemical treatment of banana cv. Poyo planting material by coating with one of the four systemic nematicide products : carbofuran, phenamiphos, isazophos and aldicarb, employed at 2 g per corm, or with a fumigant (dibromochloropropane) at 1.3 ml per corm, prevents rapid development of nematode populations (Radopholus similis, Hoplolaimus pararobustus and Cephalenchus emarginatus) after planting. The nematicidal activity lasts for about three to four months. The systemic nematicides controlled parasites by direct contact during their migration through the coating and in the soil after the dissolution of the products in it, or in roots by systemic effects. Al1 products, except dibromochloropropane, reduced the population levels, but their efficacies differed according to the nematode species. This trial also shows that population fluctuations of al1 nematode species depend on the climatic seasons : the parasite populations declined in the roots during the dry seasons.