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Rhizoctonia solani Kühn [teleomorph: Thanatephorus cucumeris (Frank) Donk.] is an important fungal pathogen widespread in all potato growing areas of the world that causes stem canker and black scurf of potato (Solanum tuberosum L.). The aim of this study was to find a simple and reliable technique for determining the pathogenicity of Rhizoctonia solani isolates. Sixty (60) isolates of R. solani obtained from sclerotia on potato tubers, collected from different market of Agadir and Casablanca regions (Morocco), were studied for their morphology, pathogenicity and molecular characteristics. They were morphologically characterised by the production of sclerotia and moniloïd cells, and by the mycelium growth capacity at 15, 20, 25, 30 and 35°C. This morphological characterisation leads to three groups of isolates. The first group Original Research Article

This research aimed to study diversity among a collection of Rhizoctonia solani strains, isolated from many crops in Morocco, based on radial mycelial growth on potato dextrose agar (PDA) at different pH and temperature levels. The in vitro antifungal efficacy of essential oils (EOs) derived from aromatic and medicinal plants of Thymus vulgaris, Origanum compactum, Rosmarinus officinalis, Eucalyptus sp., Salvia sp., Cistus ladanifer and Lavandula stoechas was also evaluated by measuring the mycelial growth of this plant pathogenic fungus after placing active mycelial plugs of each strain on Petri dishes using a disc diffusion method of EOs. The Minimum Inhibitory Concentration (MIC) of each EO was also determined. The growth rates observed under different temperatures and pH levels varied among isolates and did not show similar responses for the same levels of the two growth parameters. However, the maximum mycelial growth of the majority of isolates was reached between 20 and 30°C as well as at pH 7. Among the EOs tested, the results revealed that EO of Thymus vulgaris and Origanum compactum were very effective on controlling R. solani strain RS1 with growth inhibition rate of 75,9% and 60,6%, respectively. The MIC of these EOs was at 0.03%. According to the gas chromatography analysis, Carvacrol (61.8%) and thymol (47.8%) are the major constituents of O. compactum and T. vulgaris EOs, respectively, suggesting that these natural compounds have important potential to control R. solani and could be useful for developing effective organic fungicides.

For stored cereals, pest protection methods are mainly based on the use of synthetic insecticides. However, in the face of the pollution and toxicity problems associated with these insecticides, the search for other alternative solutions is essential. It is within this framework that local natural products collected in the region of Gharb, Morocco have been used to: evaluate their insecticidal effect on Sitophilus granarius (L.) and Tribolium castaneum (Herbst) the main pests of the stored cereals, and test the effect of these natural products on the germination of soft wheat seeds. Before bioassays, a survey was conducted in three representative areas in the region of Gharb to advance our understanding on the type of methods commonly used by farmers to protect the stored cereals against different pest. During our investigation, we found that 91% of respondents favor the use of synthetic insecticides and only cereals intended for self-consumption are treated with natural products. The results of the insecticidal effect of different natural products indicated that the highest mortality percentage was recorded with a concentration of 5% of Mentha pulegium powder and Capsicum frutescens. The former product induced 69 % and 57 % while the latter caused 36 % and 22 % mortality on the adults of S. granarius and T. castaneum, respectively. The germination test showed that these natural products have no effect on the germination rate of soft wheat grains. Therefore, these products can be potential alternative the synthetic insecticides for the protection of stored against pest infestation.