Influence of Variations in Climatic Factors and Some Cultural Practices on Knot Disease Development on Oleaster and Olive Tree (Olea europaea L,) Northwest of Morocco

Abstract

The present study is conducted to know the effect of certain cultural practices and the variation of temperature and humidity (bioclimatic stage, slope exposure) on the distribution and importance of the development of tuberculosis disease of olive trees, caused by Pseudomonas savastanoi pv. savastanoi(PSS), in  Northwest of Morocco. 1584 trees of oleaster and olive trees (cuttings and grafts) were observed during the period 2013-2014 in several groves in the northwest regions of Morocco. The percentage of infection was calculated by the number of olive trees showing the symptoms of tuberculosis caused by Pseudomonas savastanoi pv. savastanoi. The intensity of the disease in the oleaster and the olive tree was determined by counting the number of knots. The prospection was showed that olive plots are more or less attacked by tuberculosis in the northwest part region of Morocco and more apparent in olive trees in development station in Zoumi and in Boukkara (North and West oriented slopes of 68% and 28% respectively). The percentage of infection was very high in oleaster and graft plants (31% and 28% respectively) in two humid stations (Zoumi and Boukkara). The intensity of the tuberculosis disease showed that oleaster trees are most attacked. The development of olive trees is highly influenced by the symptoms in branches. The fruit size and weight were significantly higher in healthy olive trees than in those showing the symptoms of tuberculosis.