Research Article
Contrôle des populations d'Aonidiella aurantii (Maskelle) en vergers d'agrumes au Maroc
- Zaïd Guirrou, Ilham El Kaoutari, Ali Boumezzough, Mohamed Chemseddine, Abdelkader Hilal
-
- Published online by Cambridge University Press:
- 15 January 2003, pp. 3-11
-
- Article
- Export citation
-
Introduction. Le ravageur A. aurantii ou pou de Californie, non contrôlé, est capable d'entraîner en deux à trois années le dessèchement complet d'agrumes contaminés. Au Maroc, le nombre d'interventions pesticides, contre cette cochenille, par cycle de produc- tion, n'a cessé de croître depuis les années 1960. Dans ces conditions, une lutte raisonnée s'impose. Le travail entrepris a eu pour objectif de tester conjointement trois techniques d'avertissement agricole. Matériel et méthodes. Les expérimentations effectuées ont étudié la génération printanière du ravageur au cours de deux années pendant lesquelles les dégâts qu'il a entraînés ont été très importants. Onze biotopes répartis dans la zone agrumicole du périmètre irrigué du Tadla (Maroc) ont été étudiés. Le biotope 1, non traité, a servi de réfé- rence. Les trois méthodes d'avertissement utilisées conjointement ont été le piégeage des adultes mâles d'A. aurantii, le suivi de l'évolution de la dynamique des populations larvaires du ravageur et de son principal parasite Aphytis melinus, l'utilisation de la notion de degrés jours. Pour chacune de ces méthodes, un seuil d'intervention a été défini. Résultats et discussion. L'utilisation des trois techniques d'avertissement agricole et la considération des seuils requis par chacune d'elles ont permis de déterminer une période d'intervention précise et d'adapter le traitement préconisé (insecticides, huiles minérales ou aucun traitement, selon les cas) aux risques d'infestation. Par ailleurs, le parasitisme de A. aurantii par A. melinus a réduit significativement les populations du pou de Californie dans les parcelles non traitées. Conclusion. La méthode du calcul de degrés jours combinée au dénombrement des mâles du ravageur par piégeage peut constituer une base d'avertissement agricole efficace et à la portée des producteurs d'agrumes marocains. L'activité naturelle de A. melinus dans les con- ditions du Tadla reste insuffisante pour contrôler l'incidence économique de la cochenille.
Performance of Tahiti lime on Poncirus trifoliata var. monstrosa Flying Dragon in four densities
- Eduardo Sanches Stuchi, Luiz Carlos Donadio, Otávio Ricardo Sempionato
-
- Published online by Cambridge University Press:
- 15 January 2003, pp. 13-17
-
- Article
- Export citation
-
Introduction. Tahiti lime trees grafted on Rangpur lime grown in São Paulo State, Brazil, in sub-tropical climatic conditions, have a high level of vigor, poor tolerance to Phytophthora spp. and low productivity. Using Poncirus trifoliata var. monstrosa Flying Dragon rootstock which allows one to obtain dwarfed trees and high yields could solve this problem. Materials and methods. In an experiment set up in November 1994 in Brazil, the tree size, fruit production and quality of Tahiti lime grafted on trifoliate orange Flying Dragon were evaluated at four planting spaces: 4 m × 1 m (2 500 trees$\cdot$ha-1); 4 m × 1.5 m (1 666 trees$\cdot$ha-1); 4 m × 2 m (1 250 trees$\cdot$ha-1) and 4 m × 2.5 m (1 000 trees$\cdot$ha-1), in a rand- omized block design, with four trees per plot. The cultural practices did not include supple- mentary irrigation. Results. Trees planted in the 4 m × 1 m planting space had greater can- opy diameters (2.75 m) than trees planted with the other planting spaces. Whatever the densities considered, tree height did not differ. Average fruit yield (1998 to 2000) was the greatest on the 4 m × 1 m planting space with 21.6 t$\cdot$ha-1, significantly differing from the 4 m × 2.5 m planting space with 13.1 t$\cdot$ha-1. Fruit quality was affected by the plant planting space, but all the production was commercially acceptable. Discussion. The use of a high density planting of Tahiti lime grafted on P. trifoliata var. Flying Dragon would be of com- mercial interest, due to greater yields than trees in traditional cropping systems.
Evaluation of carambola cultivars in the Canary Islands
- Pedro M. Hernández Delgado, Victor Galán Saúco
-
- Published online by Cambridge University Press:
- 15 January 2003, pp. 19-26
-
- Article
- Export citation
-
Introduction. A study was set up in 1995 in the Canary Islands to determine the commercial crop potential of the carambola tree (Averrhoa carambola L.) in the warmest areas of the islands. Materials and methods. Twelve carambola cultivars were planted in three blocks, at the rate of two plants per cultivar and block, under drip irrigation at a plan- ting distance of 5 m 4 m. For each cultivar, morphological and organoleptic data of the fruit were measured. Results. Results to date appear promising, with high yields and good quality fruit for all cultivars, although some have proved susceptible to fruit fly; harvesting lasts 6 to 7 months, throughout autumn and winter. Conclusion. The cultivars recommended under the Canary Island warm climatic conditions are B-17 and Sri Kembangan (short style types), and Arkin (long style type).
Natural flowering in pineapple: inhibition by growth regulators
- Getulio Augusto Pinto da Cunha, José Tarciso Alves Costa, Domingo Haroldo Reinhardt
-
- Published online by Cambridge University Press:
- 15 January 2003, pp. 27-37
-
- Article
- Export citation
-
Introduction. Natural flowering is an obstacle for the management of pineapple production. This phenomenon is at the origin of considerable and increasing fruit losses on an international scale. The objective of this work was to determine, at various times of the year, the role of substances inhibiting the vegetative growth of the plant to prevent, reduce or delay the natural pineapple flowering of the variety `Perola', most planted in Brazil. Materials and methods. Two trials were conducted in the experimental field in Cruz das Almas, Bahia, Brasil, during the years 1996 to 1999. Various growth substances were tested at various con- centrations: propionic acid 2-(3-chlorophenoxy) (ACP) at (45, 90 and 120) mg·L-1, paclobutra- zole (PBZ) at (77.4, 155.8 and 320) mg·L-1, mepiquat chlorure (MC) at (60 and 120) mg·L-1, gibberelic acid (GA3) at (30 and 60) mg·L-1, tebuconazole (TBZ) at (60 and 120) mg·L-1 and propaconazole (PPZ) at 120 mg·L-1. The treatments were applied onto two, three or four split applications, every 15 days, from 7:00 to 9:00 a.m. and from April to July (the critical period for natural flowering in the region). Results and discussion. The results obtained show that ACP and PBZ are capable of inhibiting, reducing and delaying the natural flowering of pine- apple with the concentrations of (90 to 240) mg·L-1. The best results were obtained when the growth regulators were applied during April and May. The other products did not have an effect on the natural flowering of pineapple. Conclusion. The variation observed in the effects and efficiencies of the growth regulators used indicates the necessity of validating the best treatments under different environmental and cultural conditions. The selected growth regulators can be a valuable tool for physiological studies on the mechanisms of flowering initiation in pineapple.
Évaluation de l'intérêt du babaco (Carica pentagona Heilb.)
- Lorena Villarreal, Claudie Dhuique-Mayer, Manuel Dornier, Jenny Ruales, Max Reynes
-
- Published online by Cambridge University Press:
- 15 January 2003, pp. 39-52
-
- Article
- Export citation
-
Introduction. Le babaco (Carica pentagona Heilb.), plante équatoriale de mon- tagne, est originaire d'Équateur. Ses fruits sont particulièrement appréciés pour leur arôme caractéristique. La plante. Le babaco est un arbuste semi-ligneux de la famille des Caricacées. Cet hybride naturel se cultive en Équateur entre (1500 et 2500) m. Les rendements de production sont compris entre (60 et 80) fruits par plante et par an. Le fruit. Le fruit du babaco est une baie asperme jaune à maturité. Son arôme caractéristique se rapproche à la fois de l'ananas, du citron et de la papaye. Quand le fruit est vert, il exsude un latex qui con- tient une activité protéolytique semblable à celle de la papaye. Transformation. Le fruit est consommé essentiellement à l'état frais. La fabrication de pulpe, conserves et de fruits déshy- dratés est également possible. L'extraction et la purification des enzymes protéolytiques du latex des fruits verts pourrait être une nouvelle voie de valorisation industrielle du babaco. Tendances économiques. Grâce à des rendements de production élevés, ce fruit a éveillé un grand intérêt commercial. L'Équateur et la Nouvelle-Zélande sont les deux seuls pays où le babaco est cultivé à grande échelle. Conclusion. Le babaco présente d'intéressantes perspec- tives économiques, grâce notamment à ses propriétés sensorielles et à ses potentialités comme source d'enzymes protéolytiques.
Alternative means of recycling pineapple leaf residues
- Osumanu H. Ahmed, Ahmad M.H. Husni, Rahin A. Anuar, Mohamed M. Hanafi
-
- Published online by Cambridge University Press:
- 15 January 2003, pp. 53-60
-
- Article
- Export citation
-
Introduction. One of the challenges of the Malaysian pineapple industry is to develop new techniques for managing pineapple residues. A study was carried out to investi- gate whether K-humate can be produced from these residues. Materials and methods. Pineapple leaves were air-dried, shredded and chipped. Some of the shredded leaves were incinerated at 500 °C. Potassium hydroxide (KOH) was extracted by dissolving the ash obtai- ned in distilled water for 24 h at a ratio of 1:7 (ash / water) after which the sample was filte- red. After this extraction of KOH from the ashes of pineapple leaf residues, the remaining ash residues were further analyzed to assess the total and soluble K contents. Moreover, a given quantity of shredded leaf residues was mixed with chicken dung (as a source of microorga- nisms and nitrogen) and chicken feed. The mixture was composted with standard procedu- res. Humic acids were reconstituted using KOH from pineapple leaves with K from ash residues and K from composted pineapple leaves. Results and discussion. By reconstituting humic acids with KOH, a K-humate was produced with approximately 34.5% of its K readily soluble in water. A reconstitution of humic acids with K from ash residues produced a K-humate with approximately 3.34% of its K readily soluble in water. Conclusion. The K-humate produced from the reconstitution of humic acids with K from KOH can be used in fertigation programmes as a source of K while the K-humate produced through the reconsti- tution of humic acids with K from ash residues can be used as a source of K for fresh water fishes.