COMPARATIVE-STUDY OF INFECTION OF 3 CULTIVARS OF DATE-PALM, THE SUSCEPTIBLE, AND 2 RESISTANT (TAKERBOUCHT AT TANTABOUCHET), BY FUSARIUM-OXYSPORUM F SP ALBEDINIS

Date-palms seedlings, susceptible or resistant to fusariosis are inoculated with Fusarium oxysporum f. sp. albedinis. The first phases of seedling contamination by the pathogen were identical whatever cultivar susceptibility. Differences in the fungal development and in plant reaction were observed. Deglet-Nour cultivars known as susceptible to the disease, exhibited low early reactions related the presence of the fungus parasite. Mycelium rapidly invaded root tissues, such as the cortical parenchyma and the xylem. In the resistant cultivars Takerboucht and Tantabouchet, the fungus spread preferentially at the level of penetration sites, but propagation towards the other parts of the plants seemed to be slower than in susceptible ones. The early formation of tyloses which appeared in vessels in response to infection were insufficient to explain this phenomenon. The presence of the parasite within the root tissues of these resistant cultivars did not seem to influence the further vegetative development of plants.