Evaluation of soil receptivity of date palm groves in Arab countries to Fusarium oxysporum f. sp. albedinis , causal agent of Bayoud disease of date palm.

摘要

The Bayoud disease caused by Fusarium oxysporum f. sp. albedinis of the date palm tree is one of the most dangerous diseases in the world which is difficult to control. It is now spread in some countries of North Africa and since its appearance, it has occasioned huge losses in Morocco and Algeria and it has been discovered in Mauritania in the last few years. The Bayoud disease constitutes a serious threat for neighbouring countries and other Arab and Islamic countries that produce dates. In the frame of a regional project on Bayoud disease of date palm executed by the AOAD in 15 Arab countries, this research aims to evaluate the level of soil receptivity in 12 countries represented by 40 date palm groves localities to the pathogen fungus. The results have permitted to develop simple techniques to produce fungus chlamydospores and to evaluate soil receptivity to the fungus by measuring the spore germination percentage using soil and soil extract during only 48 hours. The results showed significant differences in soil receptivity to the pathogen fungus according to the countries and regions in each country. Moreover, the results showed the same level of soil receptivity to several strains of the pathogen from different origins and presenting different pathogenicity levels. It was shown that nearly all Arab soils present high to middle level of receptivity to the fungus and some soils are important, for example soil of Al-Ghamr in Libya and some soils in Syria, Iraq and others found in other countries. Consequently, it is advised to take precautions to prevent the entry of the disease in the countries where soils showed high receptivity. This research gives an idea, not about the disease spread, but it permits to imagine the map of spread risk of the disease according to countries that are still free and threatened by the contamination. Also, it is possible to apply this technique to evaluate soil receptivity to other wilt diseases of vegetables and other crops.