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Aims: This study was aimed to evaluate the antifungal activities of acetone and ethyl acetate extracts of Thevetia peruviana seeds on the in vitro growth of the fungus. Study Design: A randomized sample block design containing four treatments (T- = Negative control; T2= Ethyl acetate extract; T3= Acetone extract; T+=Callomil Plus) with three repetitions was used. Plant extracts were used at three concentrations: C1: 12.5 µl/ml; C2: 25 µl/ml and C3: 50 µl/ml; the chemical fungicide at the dose of 12.5 μL/ml. Place and Duration of Study: The study was conducted in the University of Yaoundé 1, Faculty of Sciences, Department of Plant Biology, Laboratory of Phytopathology and Crop Protection, and in the Institute of Agricultural Research for Development (IARD) of Yaoundé, Laboratory of Phytopathology, during the year 2019-2020. Methodology: acetone and ethyl acetate extracts of T. peruviana were prepared and used at concentrations of 12.5, 25 and 50 µl/ml. P. colocasiae was isolated from infected taro leaf cultivars "Macumba or Ibo coco" located in three different regions: west, Littoral and Centre. The various explants were were put in V8 agar medium and maintained in pure culture.  Mycelial fragments of P. colocasiae of about 0.8 cm in diameter were cut and placed in sterile Petri dishes containing Potato Dextrose Agar (PDA) medium supplemented with different concentrations of plant extracts and incubated at 23±1°C for seven days for the evaluation of the radial growth. Results: The results obtained showed that the acetone and ethyl acetate extracts have completely inhibited the growth of the strain of West at 25 μ/ml while total inhibition of the pathogen was not obtained with strain of Centre region. The lowest inhibition was obtained with the strain of Littoral region: 93.88 % for acetone extract and 90.78 % for ethyl acetate extract compare to 100 % for west and Centre region at highest concentration. Conclusion: The acetone and ethyl acetate extracts at the concentration of 25 μ/ml totally inhibited the in vitro radial growth of some strains of P. colocasiae. These extracts, which are effective against P. colocasiae, may substitute fungicides in the fight against taro leaf blight.

Maize is a major crop grown and consumed in the world and it requires a high fertilizer input. Although chemical fertilizers are an important input to get higher crop productivity, they have an impact on soil fertility, environment and human health. A field study was carried out to find alternatives to the mineral fertilization of maize. The aim of this study was to determine the influence of fertilizers on maize growth and yield while evaluating economic profitability. Four treatments (control, compost, poultry manure and mineral fertilizer NPK 20-10-10) and two maize varieties (local variety and improved variety CMS 8704) were used in a split-plot design with four replicates. Physicochemical analyses of soil and organic fertilizer were determined. Growth parameters, yield and acceptability index were evaluated. As results, poultry manure and compost are rich in nitrogen and phosphorus. At 9 weeks after sowing (WAS) the best stem diameter was obtained by the local variety in the plots fertilized with mineral fertilizer (2.83±0.31 cm). The yield of the CMS 8704 variety was significantly higher in the plots fertilized with poultry manure (2.23 t ha-1) than the yield of the local variety in the control plots (1.16 t ha-1). Principal component analysis (PCA) shows that compost and poultry manure were characterized by an increase in growth parameters as well as mineral fertilizer NPK. Poultry manure had the highest acceptability index of 1.25. In view of these results, it is clear that organic fertilizers; especially poultry manure, would have a positive impact on increasing maize production.

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This study aims to evaluate the antifungal activities of methanolic and aqueous extracts of Thevetia peruviana seeds on the in vitro growth of Phytophthora colocasiae. A randomized sample block design containing four treatments (T-: absolute control, AE, ME and Callomil Plus at the dose of 12.5 μL/ml) with three repetitions was used. Plant extracts were used at three concentrations: C1: 12.5 µl/ml; C2: 25 µl/ml and C3: 50 µl/ml. The study took place in the University of Yaoundé 1, Faculty of Sciences, Department of Plant Biology, Laboratory of Phytopathology and Crop Protection, and in the Institute of Agricultural Research for Development (IARD) of Yaoundé, Laboratory of Phytopathology, during the year 2019-2020. Aqueous and methanolic extracts of T. peruviana were prepared and used at the concentrations of 12.5, 25 and 50 μL/ml. P. colocasiae was isolated from infected taro leaf cultivars "Macumba/Ibo coco" located in three different regions in Cameroon: West, Littoral and Centre. The different leaf explants of taro were put in V8 agar medium and maintained in pure culture. Mycelial fragments of P. colocasiae of about 0.8 cm in diameter were cut and placed in sterile Petri dishes containing Potato Dextrose Agar (PDA) medium supplemented with different concentrations of plant extracts and incubated at 23±1°C for seven days for the evaluation of the radial growth. Methanolic and aqueous extracts have completely inhibited the growth of West and Littoral strains at 25 μL/mL while total inhibition of the pathogen was not obtained with strain of Centre region. The lowest inhibition was obtained with the strain of Centre region (85.1%) for aqueous extract and (70.95%) for methanolic extract compare to 100% for West and Littoral region at highest concentration. The aqueous extract at the concentration of 25 μL/ml totally inhibited the in vitro radial growth of some strains of P. colocasiae. This extract, active against P. colocasiae could be used as alternative to fungicides for the control of taro leaf blight. In other hand, the strain of Littoral region was most sensible to extracts than the others. This strain could be used to provide a genetic resource for future trials in natural conditions in greenhouse and in the field.