Phytophthora palmivora: A New Pathogen of Olive Trees in Morocco

  • Mohamed Chliyeh Laboratoire de Botanique et de Protection des Plantes, UFR de Mycologie, Département de Biologie, Faculté des Sciences BP. 133, Université Ibn Tofail, Kénitra, Maroc
  • Amina Ouazzani Touhami Laboratoire de Botanique et de Protection des Plantes, UFR de Mycologie, Département de Biologie, Faculté des Sciences BP. 133, Université Ibn Tofail, Kénitra, Maroc
  • Abdelkarim Filali-Maltouf Laboratoire de Microbiologie et Biologie Moléculaire, Faculté des Sciences, Université Mohammed V Agdal, Av Ibn Batouta, BP 1014 Rabat, Maroc
  • Cherkaoui El Modafar Laboratoire de Biotechnologie, Valorisation et Protection des Agroressources, Faculté des Sciences et Techniques Guéliz, B.P. 618, 40 000 Marrakech, Maroc
  • Abdelmajid Moukhli UR, Amélioration génétique des plantes, Institut national de la Recherche agronomique F- 40 000 Marrakech, Maroc
  • Ahmed Oukabli Institut national de la Recherche agronomique, Amélioration des plantes et Conservation des ressources phytogénétiques CRRA, BP 578, Meknès, Maroc
  • Rachid Benkirane Laboratoire de Botanique et de Protection des Plantes, UFR de Mycologie, Département de Biologie, Faculté des Sciences BP. 133, Université Ibn Tofail, Kénitra, Maroc
  • Allal Douira Laboratoire de Botanique et de Protection des Plantes, UFR de Mycologie, Département de Biologie, Faculté des Sciences BP. 133, Université Ibn Tofail, Kénitra, Maroc
Keywords: Olive tree crown dieback, root rot, defoliation, Phytophthora palmivora, Koch’s postulate, pathogenicity

Abstract

In spring of 2012, olive-trees with crown dieback, root rot and defoliation were observed in two years old olive tree in commercial plantations of tree nurseries in Sidi Taibi and in twenty to fifty years old field trees in Souk El Arbaa olive crops in Northwest of Morocco (Gharb area). The objective of this study was to isolate the responsible pathogen of the observed symptoms to the olive trees, to demonstrate its pathogenicity and fulfill the Koch´s postulate. Phytophthora palmivora was consistently isolated from roots (56%) and stems (73.6%) of the young olive trees and 85% from stems of field trees. Koch’s postulate was completed using two isolates of Phytophthora palmivora on 2-year old plants of Dahbia and Haouzia varieties grafted onto wild olive-trees. The affected branches percentages (Pab%) of the inoculated olive plants with the isolate 1 were higher (81.8% for Dahbia and 68% for Haouzia) than those what were inoculated with the isolate 2 (43% for Dahbia and 32% for Haouzia). The reisolation percentages (Pr%) of isolate 1 (84%) and isolate 2 (76%) in the roots of Dahbia variety were higher than isolate 1 (48%) and isolate 2 (55%) in roots of Haouzia variety. The reisolation percentage of isolate 1 in the stem of Dahbia (64%) was higher than that in the stem of Haouzia (41.33%). No significant difference was observed between the Reisolation percentages of isolate 2 in stem of Dahbia olive plants (38%) and in stem of Haouzia olive plants (33%). The pathogenicity of P. palmivora was demonstrated in the olive plants and this was the first report of this pathogen in Moroccan olive trees.

Published
2017-05-25
Section
ARTICLES