New Appearance of Phytophthora palmivora as a Pathogen of the Olive Trees in Sidi Kacem Region (Morocco)

Abstract

This study aims to study and evaluate the presence and geographical distribution of Phytophthora palmivora, the causal agent of the olive trees wilting in Morocco. In 2015 surveys, carried out in Sidi Kacem region, made it possible to note the presence of olive trees showing symptoms of dieback. The diseased samples were taken from these trees in order to determine the causative agent of the disease. P. palmivora was isolated and the Koch’s postulate was verified. The pathogenicity of one isolate, selected among other isolates was studied. After five months of inoculation, this isolate proved able to induce different types of symptoms in olive plants: growth reduction in the vegetative and the root parts and the number of Leaves and buds. Sometimes the newly formed buds dry up. The values of the growth parameters are very low in the inoculated seedlings, the number of leaves, branches and buds are respectively 101, 12 and 13.5. On the other hand, these values are respectively 338.66, 29.83 and 11.83 in the control plants, the root mass of the Inoculated seedlings is also very low (13.1 g) versus 75.1 g for the control seedlings. The fungus was found in different parts of the inoculated olive plants: roots, stems and dried out buds.