Introduction. The Asian citrus psyllid, Diaphorina citri Kuwayama, is particularly harmful tocitrus plantations as it is one of the two psyllid vectors of the citrus greening disease or Huanglongbing. Thisdisease, which limits the longevity of trees, is due to an intracellular bacterium which mainly affects the phloem.Past experience of biological control of D. citri in Reunion Island. In Reunion Island, this disease,detected in 1967, was the main obstacle to the development of the cultivation of citrus fruit. Control of the vectorD. citri, by introducing from India and multiplying on site the specific parasitoid Tamarixia radiata(Waterston), was carried out during 1978 when nearly 4600 adult parasitoids were released. The success of T.radiata combined with the distribution of healthy plant material was at the origin of the revival of the cultivation ofcitrus fruit in Reunion Island. Programme for a biological control of D. citri in Guadeloupe. In Guadeloupe,D. citri was reported in January 1998. No trace of insect parasitism was found and only one fungus, Hirsutella citriformis Speare, proved, under certain conditions, capable of regulating the populations of thispsyllid. Taking into account the experience in Reunion Island and that the greening disease has not shown up inGuadeloupe, the introduction of T. radiata from Reunion Island was made in January 1999. About 1000 T.radiata were released all over the Guadeloupe islands. At present, just a little more than 1 year after the lastreleases, the parasitoid is established and present in almost all the citrus orchards where psyllid populations havedecreased considerably. Quite favorable biological characteristics play a great part in explaining the excellenteffectiveness of T. radiata in biological control programmes against D. citri.

Introduction. Brazil is one of the most important producers of passion fruits. Inoculation witharbuscular mycorrhizal fungi (AMF) may reduce or eliminate the need for phosphate fertilization on this crop. Weinvestigated the response of passion fruit seedlings to inoculation with AMF and phosphorus (P) supply. Materialsand methods. A greenhouse experiment was carried out in a factorial design. The seedlings were inoculated with100 spores per plant of single or mixed AMF inoculum on sterilized or non-sterilized soil which was amended with (11 or 30) mgP × dm-3 soil applied as superphosphate or used unfertilized (4 mgP × dm-3 soil). Relative mycorrhizal dependency (RMD) of passion fruit was estimated for eachtreatment of inoculation, soil sterilization, and P level, by expressing the difference between the dry mass ofmycorrhizal plants and non-mycorrhizal plants as a percentage of the dry mass of mycorrhizal plants. Results.Inoculation was effective only on plants grown in sterilized soil with (4 or 11) mgP × dm-3 soil. Plants were "facultatively mycotrophic" when associated with AMF and when receiving a supply of 30 mgP × dm-3 soil. Seedlings in unfertilized soil with 4 mgP × dm-3 soil wereexcessively dependent on the mycorrhizal association. In soil with 11 mgP × dm-3 soil, seedlingswere marginally to moderately dependent, depending upon the AMF species used. All inoculated seedlings, withoutconsidering soil sterilization, were marginally dependent in soil with 30 mgP × dm-3 soil. Insterilized soil, independently of P, they were moderately dependent. However, in the same soil, with 30 mgP × dm-3 soil, the seedlings were marginally dependent. Discussion - conclusion. The relativemycorrhizal dependency (RMD) of the passion fruit cultivar used was influenced by the species of the inoculated AMF,soil sterilization and soil P level. Passion fruit obtained significant benefit from inoculation with AMF; thus, thesefungi can be used to improve plant growth even without P fertilization.

Introduction. The date palm tree is one of the fruit trees most cultivated in the Arabian Gulf States. Bioregulators were used for the quality and productivity improvement of date palm tree fruits. A study was conducted to assess the relative effectiveness of GA3, NAA, ethephon and a mixture of growth regulators on some fruit characteristics and productivity of the Barhee date palm tree cultivar. Materials and methods. Five selected female uniform date palm trees of the cultivar Barhee were pollinated on March 5-15, 1994, 1995 and 1996, by placing eight fresh male strands on the female spadix center (flower cluster).Ten flower clusters were used on each tree and divided into five groups of two flower clusters. Each of these groups was subjected to one of the following treatments: control (water), 150 mg GA3 × L-1, 100 mg NAA × L-1, 1 000 mg ethephon × L-1 and a mixture of these three growth regulators. Then the fruit setting, fruit flesh and dry matter percentages, the total soluble solids, the fruit ripening, and the fruit weight per bunch and per tree were measured. Results and discussion. The data showed that the application of GA3 or ethephon on flower clusters of Barhee date palm trees had no constant effect on fruit characteristics and productivity of trees. NAA or growth regulator mixture applications on Barhee flower clusters reduced the fruit dry matter and fruit ripening percentages and increased the fruit weight per bunch and per tree. Conclusion. Treatments of Barhee date palm flower clusters, 20 d after pollination, with NAA or the specific growth regulator mixture decreased the dry matter percentage and the fruit ripening and increased the fruit flesh percentage and the date palm tree yield, therefore, these treatments could be recommended to improve the productivity of date palm trees in the region.

Introduction. Le safoutier (Dacryodes edulis, Burseraceae) est un arbre dont les fruits sont très appréciés par les populations de son aire de répartition. Plante allogame, la multiplication par semis ne permet pas d'effectuer une multiplication conforme de l'arbre sélectionné. La présente étude a eu pour principal objectif de mettre au point une technique de régénération in vitro des bourgeons axillaires et apex prélevés sur de jeunes plants issus de la germination de graines, afin d'adapter ultérieurement cette technique au clonage d'arbres adultes par utilisation de repousses formées après recépage. Matériel et méthodes. Des nœuds et apex prélevés sur des plants de Dacryodes edulis issus de la germination de graines ont été mis en culture in vitro sur un milieu Murashige et Skoog dilué de moitié (MS 1/2). Les effets du charbon actif et de la benzyleadéninepurine (BAP) sur le débourrement des explants ont été étudiés, de même que l'influence de l'acide naphtalènacétique (ANA) et de la photopériode sur l'enracinement. Résultats. Le milieu MS 1/2 additionné de charbon actif à 2g × L-1 et de BAP à 2,22 µM ou 4,44 µM a provoqué le meilleur débourrement des bourgeons axillaires et une bonne croissance des tigelles. L'ANA à 5,37 µM a favorisé l'enracinement. Une période de 7 j à l'obscurité s'est révélée favorable à l'induction racinaire. Deux types de racines ont été observés : les racines néoformées (issues de cals) et les racines adventives. L'acclimatation a été faite avec succès sur substrat constitué de tourbe et vermiculite. La régénération des vitroplants à partir des nœuds et apex permet de distinguer le long de la jeune plante un gradient morphogénétique acropétale. Discussion et conclusion. Ces résultats pourront être exploités pour la mise au point d'une micropropagation conforme à partir de jeunes repousses formées après la taille d'un safoutier présentant des caractéristiques intéressantes.

The plant. The camu-camu [Myrciaria dubia (H.B.K.) Mc. Vaugh] is a shrub from the Myrtaceae family. It grows naturally in floodable and swampy areas of the Amazonian basin. This plant is cultivated in Peru and Brazil with fruit yields ranging from (12 to 20) t × ha-1 × year-1. The fruit. The fruit, from (1 to 3) cm in diameter, is pink to dark purple; it is the highest known source of natural vitamin C, providing (850 to 5,000) mg mg × 100 g-1 edible portion. The market. In the last few years, both national and international demand for the camu-camu fruit has drastically increased for the production of health food or of natural vitamin C. The current fruit production is not sufficient to satisfy the market. Conclusion.M. dubia stands out amongst other Amazonian fruit species as having a high economic and social potential. Little information is available on its processing, showing the need for research in this area.

Introduction. Apples are potentially subject to blue mold decay caused by Penicillium expansum ifstored at 1 °C for three or more months or if wounded during handling. Results from trials with applescontaminated with conidia of P. expansum and fumigated in small chambers with acetic acid (AA) vapor indicatedthat fruit could be sterilized to reduce decay without effect on fruit quality. The objective of this study was todetermine if larger quantities of apples treated with AA vapor would have less decay after storage and/or wounding. Itwas also important to determine if fumigation would affect apple quality and aroma. Materials and methods. Applecultivars were harvested at commercial maturity for use in AA fumigation trials. Apples artificially or naturallycontaminated with conidia of P. expansum were fumigated with AA vapor in a 1 m3 gas tight chamber at10 °C for 1 h to 24 h or dipped in 450 μg thiabendazole × L-1 solution. Fruit fumigatedin standard wooden or plastic apple boxes, or small wooden bins were either wounded and evaluated for decay after a weekat 20 °C or stored at 1 °C for three or more months and evaluated for decay. Then apple quality wasassessed. Results. Apples naturally contaminated with Penicillium spp. that had been stored at1 °C in air storage and treated with AA vapour had 50% less decay than the control fruit. In anotherexperiment, AA fumigation was as effective as thiabendazole in reducing decay. AA fumigation reduced decay of fruitcoming out of storage for apples stored for 3 months, and a second AA fumigation reduced infection of wounds on thesesame apples. AA fumigation before storage did not affect apple quality or vinegar aroma. Discussion. AA fumigationshowed great potential for reducing decay in stored apples. It could be used as an organic alternative to syntheticfungicides for control of blue mold decay.

Introduction. L'insuffisance en froid hivernal dans les zones de plaine au Maroc constitue un facteur limitant à la production du pommier. Les effets du dinitro-orthocrésol (DNOC), produit connu pour lever la dormance chez d'autres arbres fruitiers, ont été évalués vis-à-vis du débourrement de pommiers `Golden Delicious' cultivés dans de telles conditions climatiques. Matériel et méthodes. Un mélange de DNOC à 0,15 % et d'huile de pétrole utilisée a 3 % ou 5 % a été appliqué à des pommiers, à deux dates différentes. La production des arbres ainsi traités a été comparée à celle d'arbres témoins non traités. L'évaluation des traitements a porté sur les taux de débourrement des bourgeons végétatifs et floraux, la floraison, la nouaison, la croissance végétative et la production. Résultats. La solution utilisée a avancé la date de débourrement et amélioré de façon significative les taux de débourrement des bourgeons végétatifs et floraux, la croissance végétative, ainsi que le rendement et le calibre des fruits. Conclusion. Le mélange [DNOC + huile du pétrole] a permis d'avancer et de regrouper le débourrement de l'ensemble des bourgeons et a amélioré le calibre et la production du pommier `Golden Delicious'. Ce mélange pourrait donc être utilisé pour pallier le manque en froid hivernal des zones de plaine du Maroc, caractérisées par un hiver doux.