Introduction. Plants develop mechanisms that allow them to compartmentalize injuries that they suffer during their life. In trees, pruning and injection treatments must be used in accordance with precise rules to reduce risks resulting from the injuries created. Sealing in palms. Palms, contrary to widespread belief, are quite capable of “healing” injuries (sealing); because of an anatomy quite different from trees, the sealing process in palms is much simpler. Compartmentalization of injection wounds. The controversy on the use of injection in trees is due essentially to initial mistakes that have then been rectified. Injection in palms against the red palm weevil. For palms, for decades, this technique has been employed without problems and with great efficiency against various pests, including Rhynchophorus ferrugineus, the red palm weevil (RPW). Its use has been reserved for exceptional situations either to face abnormal pest proliferation, uncontrollable by other techniques, or to implement eradication programs. Integrated eradication program. In such a program, the main aim of injection treatments is preventive. With long-persistence insecticides, the number of treatments could be greatly reduced. The resulting savings in time and money would enable the organization of the treatments of all the palms located in an infested area, and consequently the rapid eradication of the pest. New perspectives. We established that insecticides applied by injection were capable of protecting palms with only two or even one treatment per year. These results suggest a radical improvement in programs to eradicate RPW, while considerably reducing the risks to health and the environment compared with spray treatments.

Introduction. Bacterial canker,caused by P. syringae pv. syringae,is an important disease of stone fruit worldwide. The possibilityof P. syringae pv. syringae infectionthrough leaf scars and lenticels was evaluated in cherry, peachand prune. Materials and methods. Laboratory and fieldinoculations were performed using cherry, peach and prune stemsto evaluate leaf scar age, chilling and freezing-thawing on bacterialinfection through leaf scars and lenticels. Results and discussion. Increasingleaf scar age was associated with significant decreases in diseaseincidence and length of lesions resulting from leaf scar inoculationwith Pseudomonas syringae pv. syringae incherry, peach and prune. A significant reduction in incidence andlesion length was observed after 4 h of air exposure, and both measuresof infection were reduced to essentially 0 by 2 days of exposure. Prolongedchilling temperature (2.2 °C) prior to leaf removal had no cleareffect on disease incidence of leaf scar infection, but significantlydecreased lesion length due to leaf scar infection. Cherry was more susceptibleto P. syringae pv. syringae infectionthrough leaf scars than peach and ‘French’ prune. The leaf scar inoculationresults were consistent with the previous studies. The disease incidenceof lenticel infection caused by bacterial inoculation in ‘French’prune was very low, but significantly higher than the water control.Freezing-thawing significantly increased both the disease incidence andthe lesion size via lenticel infection. The lenticel inoculationdata suggest that P. syringae pv. syringae infection throughlenticels is possible under field conditions.

Introduction. Bacterial canker, caused by Pseudomonas syringae pv. syringae, is a devastating disease of stone fruit worldwide. The effects of mineral nutrients and freezing-thawing on bacterial canker susceptibility were evaluated using potted peach trees in an attempt to understand predisposing factors in bacterial canker of stone fruit. Materials and methods. A split-plot experimental design with randomized complete block main plots (i.e., inoculations associated with freezing-thawing or nonfrozen pretreatments) and subplots of trees with the seven treatments (i.e., solutions deficient in N, P, K, Ca, Mg or Fe, respectively, and a full nutrient control) was adopted to study the effect of mineral deficiency and freezing-thawing on peach susceptibility to bacterial canker. Results and discussion. Phosphorus deficiency was the only treatment to significantly decrease lesion length that developed after inoculation with P. syringae pv. syringae, compared with the control trees that received full nutrients. Nitrogen and potassium deficiency treatments significantly decreased bark nitrogen and potassium concentrations accordingly, but had no clear effect on lesion sizes. Inoculation during freezing-thawing cycles significantly increased lesion length. In another independent experiment, nitrogen deficiency significantly increased the number of P. syringae pv. syringae leaf scar infections, but the subsequent infection was limited to a few millimeters. Nitrogen-deficient trees, which had higher [carbon / nitrogen] ratios, developed lesion sizes equivalent to trees provided with full nutrients. Collectively, these data suggest that, in the absence of other major predisposing factors (i.e., low soil pH or ring nematodes), mineral nutrients may play a minor role in the susceptibility of peach to bacterial canker.

Introduction. Les dommages provoqués par la cercosporiose des agrumes, dus à Phaeoramularia angolensis, sont à l'origine de pertes de récolte ou d'écarts de tri pouvant varier entre (50 et 100) % de la production. Or tous les organes attaqués par la maladie - pétales des fleurs, feuilles et surtout peau des fruits - renferment des huiles essentielles à haute valeur marchande. Une étude a été réalisée pour connaître l'influence des attaques de cette maladie sur le rendement d'extraction et la qualité des huiles essentielles de peau d'orange. Matériels et méthodes. L'extraction d'huile essentielle a été réalisée par hydrodistillation à partir de fruits récoltés à maturité et les extraits ont été analysés par chromatographie en phase gazeuse afin de déterminer leur composition chimique. Résultats et discussion. Le rendement d'extraction des huiles essentielles a diminué en fonction de la gravité des attaques (jusqu'à 40 % de baisse). Cette baisse n'a été significative que lorsque les attaques dépassaient deux lésions par fruit. Les extraits obtenus de fruits attaqués à divers degrés ont présenté quelques variations quantitatives de leurs constituants. Une diminution de certains composés dans les fruits malades s'est accompagnée d'une augmentation de leur forme oxygénée. L'augmentation de la quantité globale d'aldéhydes a été observée dans les fruits malades, ce qui pourrait se traduire par une amélioration de la qualité des huiles essentielles. Mais, en même temps, les oxydes caractéristiques de la dégradation de ces huiles essentielles ont augmenté. Conclusion. Ce travail qui doit être approfondi a permis d'acquérir de premières données sur les pertes de rendement et l'évolution de la composition des huiles essentielles de peau de fruits pouvant être attribuées aux attaques de la cercosporiose.