ABSTRACT
The study was conducted to determine fungal communities associated to strawberry plant roots, densities of nematodes in fumigated soil and physico-chemical properties of soil in three commercial strawberry plots (Dlalha, Ouled Aguile and Gnafda) located in Gharb region and visited three times during 2013-2014 season. Under a slight variation of soil temperature and humidity with specific physico-chemical characteristics, a high infestation level of soil by nematodes was marked in the studied farms over the periods of sampling. The lowest number was observed in the first visit attaining 1000 units/g of soil, increased to 5000 units/g of soil in the second sampling period at one site and in the last visit, a significant decrease trend occurs for the big plot which the number of nematodes was reduced to 1500 units/g of soil. The analysis of fungal communities colonizing roots of strawberry plants showed the presence of 13 fungal species. Rhizoctonia solani presented a higher frequencies of isolation from roots of Festival variety reaching respectively 36% and 26.72% in the first and the second visits of Dlalha farms compared to those recorded in the second visit of Ouled Aguile (18%) and Gnafda (13.6%) farms. The Fusarium genus was represented by F. solani, Fusarium sp.1 and Fusarium sp.2 detected at frequencies not exceeding 7.08%. Those of C. gloeosporioides reached 12%, Phytophthora sp. (15.8%). In addition, the appearance of A. alternata, C. herbarum, Aspergillus sp., Circinella sp., Ulocladium sp. and Trichoderma asperellum was more frequent during the three sampling periods.
ABSTRACT
During a survey on fungi associated with decline symptoms on strawberry plant of Venicia variety, one species belonging to the Botryosphaeriaceae family was isolated. Based on morphological and cultural characteristics, this species identified as Neofusicoccum parvum was reported for the first time in Morocco. To verify the pathogenicity of the fungus, detached leaves of three strawberry varieties were inoculated artificially by depositing over their intact surface mycelia plug or conidial suspension from N. parvum. Severity index was greater on festival leaves reaching 88% compared to 77.73% on Sabrina. In the third treatment, Guariguette showed a low susceptibility with a severity index in order of 25.07%. Conidia concentration on the leaf surface of the Festival and Sabrina strawberry leaves was respectively 1.62 105and 1.2 105 conidia cm-2. Otherwise, in the second treatment, it has been reduced to less than 1.41105 1.16 and 105 conidia.cm-2 on leaves of Festival and Sabrina respectively. After inoculation, the fungus was re-isolated from the lesions to verify Koch’s postulates.