Comparative pathogenicity of Colletotrichum spp. against different varieties of strawberry plants (Fragaria ananassa) widely grown in Morocco

The evolution of anthracnose symptoms on the aerial part (leaves, stems and strawberries) of three varieties Fortuna, Camarosa and Festival of strawberry plants inoculated with the conidial suspensions of Colletotrichum acutatum and Colletotrichum gloeosporioides isolates was followed. The severity index and infection coefficients increased in function of time. Seven days after inoculation they were low not exceeding 13.43% and 43.33, but they increased four weeks after inoculation, respectively, to 37.96% and 99 on strawberry plants of the Camarosa variety, 54.44% and 105 on those of Fortuna and 51.12% and 85 on those of Festival. At the sixth week, the severity index and infection coefficients became very high, reaching respectively 100% and 408 on Fortuna plants inoculated with C. gloeosporioides isolate (Coll3) followed by Coll2 (89.28% – 300), Coll1 (86.66% – 378) and Coll4 (80.45% – 198) of C. acutatum species. Similarly, the isolate Coll3 caused fruit rot; the percentage of rotten strawberries was 100% on Fortuna variety, 83.33% on Festival and 70.25% on Camarosa. A positive re-isolation of the tested Colletotrichum isolates has been noted from leaves of strawberry varieties and negative from crowns or the roots. A significant to moderate reduction in fresh and dry weights of the aerial part and roots was noted in inoculated strawberry plants compared to the control

Inventory and world geographical distribution of the olive tree (Olea europaea L.) diseases caused by viruses, bacteria and phytoplasma

The objective of this work is to prepare an Inventory about the viral and bacterial diseases of the olive tree (Olea europaea L.) and to study their Geographical distribution in the world. Fifteen viruses were considered as pathogens on the olive tree, these viruses were reported in 22 countries in five continents showing different symptoms on different olive tree varieties. All viruses were reported in Italy, some of these viruses were found only in the Eurepean continent, such as Olive vein yellows associated virus (OVYaV), Olive yellow mottling and decline associated virus (OYMDaV), Olive mild mosaic virus (OMMV) and Olive semilatent virus (OSLV). Two bacteria were reported as pathogen on the olive tree; Pseudomonas savastanoi. pv. savastanoi responsible bacteria of thr olive knot; a serious disease of olive (Olea europaea L.) in the Mediterranean region. This bacteria was detected in 22 countries in five continents, the majority of these countries exist in the Mediterranean Basin. Another bacteria was Xylella fastidiosa responsible of the quick decline syndrome of olive (OQDS), was deteted in Europe in four countries (Italy, Spain, Portugal and Slovenia) and in America in three countries (USA, Argentina and Brazil). Phtoplasmas was reported in 5 countries in three continents (Europe, Asia and Australia)

Diversity of endomycorrhizal fungi in the rhizosphere of chickpea in Morocco

The endomycorrhizal fungi diversity in the rhizosphere of chickpea (Cicer arietinum L.) and the evaluation of root mycorrhizal level were studied in six regions of Morocco: Tahla, Sefrou, Souk Larbae, Souk Tlat, Ouazzane and Jarf Melha. All chickpea roots are carrying endomycorrhizal structures. Root mycorrhizal parameters varied from one site to another, and the highest frequency and intensity of mycorrhization was recorded in the roots of chickpea plants at the two sites Tahla and Jarf Melha respectively, 83%, 33% and 25.03%. In addition, the highest arbuscular content was also noted in the roots of plants growing in the site of Tahla (22.18%) while the lowest content was noted at the site of Sefrou (2.07%). However, the vesicles were not observed in all the sites. The highest numbers of endomycorrhizal spores were recorded in the rhizosphere of plants collected in Jarf Melha and Tahla, respectively, 74 and 41 spores / 100 g soil. All spores found in the studied sites are represented by 22 morphotypes belonging to 7 genera: Glomus (13 species), Acaulospora (4 species), Gigaspora (one species), Radekera (one species), Entrophospora (one species), Pacispora (one species), Dentiscutata (one species)

Effect of the Number of Years of Soil Exploitation by Saffron Cultivation in Morocco on the Diversity of Endomycorrhizal Fungi

The diversity of endomycorrhizal fungi in the rhizosphere of Crocus sativus has been studied at five sites in the Taliouine region (Tinfat), located in Taroudant Province (Morocco), according to the number of years of soil exploitation by Saffron cultivation. In all sites, the roots of Crocus sativus carry structures of endomycorrhizal fungi. Root mycorrhizal frequencies are very high in site 1 (93.33%); site 2 (96.67%); site 4 (90%) and in site 6 (93.33%). In these sites, the spore density is, respectively, 39, 58, 138, 99 spores / 100 g of soil. The frequency of root mycorrhization is lower at the site (76.66%) which also exhibited a spore density of 27 spores / 100 g of soil. The identification of isolated spores made it possible to note the presence of 36 species belonging to 6 genera: Glomus (15 species), Acaulospora (10 species), Scutellospora (6 species), Gigaspora (2 species), Pacispora (2 species), Entrophospora (1 species). Species such as Glomus clarum, G. etunicatum, G. aggregatum, G. intraradices, Acaulospora laevis, Scutellospora coralloidea, were present in all studied sites. The greatest richness of MA fungi was registers in the site at four successive years of exploitation by Saffron (24 species), with a Shannon diversity index H ‘= 2.82 which is the highest among all studied sites, followed by the site at six years of occupation by Saffron (21 species), with H ‘= 2.61, while the lowest number of species was recorded in sites of two, three and ten years of exploitation of sol by Saffron, with H ‘= 1.77, respectively; 2.12 and 2.44. This decrease in endomycorrhizal species richness confirms that Crocus sativus residues are probably the cause. In fact, the prolonged occupation of plots with safrana has an allelopathic effect on mycoflora and on the yield of Saffron

Effects of a Composite Endomycorrhizal Inoculum on Olive Cuttings under the Greenhouse Conditions

This study was carried out in a nursery to evaluate the impact of mycorrhizal fungi on the cutting's root growth, and root colonization of a Moroccan olive variety ‘Picholine Marocaine' under greenhouse conditions during 2 years of cultivation. The results revealed that the inoculation with a composite inoculum of arbuscular mycorrhizal fungi (AMF) stimulated an early root formation and high development of vegetative shoots in inoculated cuttings respectively, 35 days (50 days in the control plots) and 40 days (60 days in the control plots) after their culture. The progressive establishment of mycorrhizal symbiosis in the roots of the inoculated plants showed that the root and vegetative masses were respectively 24 g and 19.5 g two years after inoculation. The average height and the leave's number of the inoculated plants relative to the control were respectively s 42/ 12 cm and 145/12. The newly formed roots were mycorrhizal and present different structures characteristic of AMF: arbuscules, vesicles, hyphae and spores, whose frequency and intensity reached 90% and 75% two years after cuttings cultivation. The arbuscular and vesicular contents and the number of spores were 67%, 96% and 212 spores/ 100 g of soil respectively. The fourteen species of mycorrhizal fungi isolated from the rhizosphere belong to 4 genera (Glomus, Acaulospora, Gigaspora, and Scutellospora) and three families (Glomaceae, Acaulosporaceae and Gigasporacea).The Glomus genus was the most dominant (65%) followed by the Gigaspora genus (22%). Glomus intraradices, Gigaspora sp.2, Glomus versiformes are the most abundant species, their frequency of occurrence are respectively 30%, 21% and 16%

Mycorrhizal status of Lycium europaeum in the coastal dunes of Mehdia (Northwest of Morocco)

Objective: This study describes the mycorrhizal status of Lycium europaeum in the mobile and fixed dunes in the coastal area of Mehdia (Northwest of Morocco).Methodology and results: Evaluation of the mycorrhization level in the roots was effected and the identification of the arbuscular mycorrhizal fungi was based on the morphological characters of the isolated spores from soil and root samples collected from the rhizosphere of Lycium europaeum developing in the bright and fixed dunes of Mehdia coastal dunes. Different structures of the arbuscular endomycorrhizal fungi and the endophytes were present in the roots of L. europaeum. 100% of the roots were mycorrhized in both sites with an intensity of 18.4% in the fixed dunes and 10.43% in the mobile dunes. The arbuscular and the vesicular contents were respectively 6.2 - 1.2 % and 11.83 - 3.96 % in mobile and fixed dunes. Spores number was 75 (mobile dunes) and 50 spores/100 g of soil (fixed dunes). 29 species of the mycorrhizal fungi were isolated, divided into seven genuses (Gigaspora, Acaulospora, Diversipora, Entrophospora, Scutellospora, Paraglomus and Glomus). The genus Glomus alone was represented by 20 species. The two sites of the studied dunes have only two common species: Glomus claroideum and Scutellospora nigra.Conclusion and application of results: Lycium europaeum, mycotrophic species, may be a good candidate to fix the mobile dunes and to protect the reserve of Sidi Boughaba threatened by the progress of sand. Mycorrhization probably facilitates the installation of this species, suspected rare in Morocco, which grows well in the mobile dunes.Keywords: Morocco, coastal dunes, Lycium europaeum, mycorrhizal status, arbuscular endomycorrhizal fungi

Mycorrhizal status of Olea europaea spp. oleaster in Morocco

Objective: This study describes the mycorrhizal oleaster status (Olea europaea ssp. oleaster:) in the Moroccan ecosystems. Methodology and results: Soil samples were extracted from the rhizosphere of the oleaster tree groves in several regions of Morocco. The frequency and the levels of the arbuscular mycorrhizal fungi (AMF) inside the root bark were measured by assigning an index of mycorrhization from 0 to 5 (Derkowska et al., 2008). The results showed that the AM fungal colonization structures were hyphae, coils and vesicles. The mycorrhizal frequency and intensity reached respectively 70 and 6% in the Bnifougass site. The highest spore density was in the order of 364 g soil spores/100 g and the genus Glomus was the dominant one. The tentative identification test of VAM (Vesicular-Arbuscular Mycorrhizae) species, isolated from the rhizosphere of the oleaster trees, revealed the presence of five fungus species: Glomus intraradices, Glomus clarum, Glomus versiforme, Acaulospora colossica, Scutellospora heterogama. Conclusion: In all the studied sites the oleaster roots were Mycorrhized. These results open up many opportunities for the application of the controlled mycorrhization in the oleaster plants nurseries production Keywords: Morocco, oleaster, rhizosphere, endomycorrhizae

Effet in vitro de différents niveaux NPK sur la croissance mycélienne et la sporulation de cinq pathogènes foliaires du riz : Helminthosporium sp. et Curvularia lunata

Objectif : Le principal but de cette étude est d'examiner in vitro l'effet d'azote, de phosphore et de potassium, à différents niveaux, sur deux séquences biologiques de cinq pathogènes foliaires du riz (Oryza sativa) : Helminthosporium oryzae, H. sativum, H. australiensis, H. spiciferum et Curvularia lunata, notamment la croissance mycélienne et la sporulation.Méthodologie et résultats : Trois milieux de culture organiques sont utilisés pour tester l'effet NPK sur la croissance mycélienne et la sporulation des cinq espèces fongiques testées : PDA, Farine de riz et Extrait de malt. Les sources d'azote, de phosphore et de potassium sont incorporées séparément dans le milieu de culture à des concentrations croissantes, 0,01 M (C1), 0,025 M (C2), 0,05 M (C3), 0,1 M (C4) et 0,15 M (C5), avant la stérilisation. Deux critères de notation sont pris en considération : la croissance mycélienne et la sporulation des espèces fongiques. Les résultats obtenus ont montré que les Helminthosporium et Curvularia lunata testés ont des comportements variables, croissance mycélienne et sporulation, sur des régimes nutritionnels en azote, phosphore et potassium. Ces comportements sont fonction de milieu de culture, la dose et la source de l’élément fertilisant incorporé.Conclusion et application de résultats : Cette étude in vitro sur la croissance et la sporulation a montrée une grande adaptation des pathogènes foliaires du riz (Helminthosporium et C. lunata) aux différents niveaux de NPK testés, une telle adaptation laisse croire que l'apport des nutriments a plus d'effet sur l'hôte que sur le pathogène lui-même. Ces observations seront utiles pour aborder in vivo l'effet de la fertilisation sur les maladies foliaires du riz

Diversity of arbuscular mycorrhizal fungi in the rhizosphere of Coffea arabica in the Republic of Yemen

Objective: This study describes the status of mycorrhizal fungi in coffee (Coffea arabica) in the Yemeni ecosystems. Methodology and results: Soil samples were extracted from the rhizosphere of the coffee tree groves in several regions of Yemen. The frequency and the level of colonization of the arbuscular mycorrhizal fungi (AMF) inside the root bark were measured by assigning an index of mycorrhization from 0 to 5 (Derkowska et al., 2008). The results showed that the AM fungal colonization structures were hyphae, coils and vesicles. The mycorrhizal frequency and intensity reached respectively 100 and 48 % in the Taiz 2 site. The highest spore density was in the order of 100 spores/100 g of soil and the genus Glomus was dominant. The tentative identification test of VAM (Vesicular Arbuscular Mycorrhizae) species, isolated from the rhizosphere of the coffee trees, revealed the presence of five fungal species:, Glomus proliferum, G. etunicatum, Acaulospora sporocarpia, Acaulospora sp.1, Archeospora sp. 1, Scutellospora nigra. Conclusion and application of results: In all the studied sites the coffee roots were mycorrhized. These results demonstrate the existence of opportunities for the application of controlled mycorrhization in the coffee Seedlings nurseries. Keywords: Yemen, Coffea arabica, rhizosphere, endomycorrhizae