Background: Late blight caused by Oomycete Phytophthora infestans remains a huge problem in potato production and one of the most severe crop diseases worldwide. In Cameroon, the populations characterization of this pathogen remain very little known. Aims: This study aims to characterize isolates of P. infestans collected in twelve localities of Highlands zone of Cameroon. Study Design: Twelve localities in three main potato production areas of the Highlands agro-ecological zone (HAZ) in Cameroon were selected for sample collection. The phenotypic parameters of sporangia were measured. The presence of mating types and pathogenicity tests on detached leaflets of two potato varieties (MANATE and CIPIRA) were assessed. Results: A total of 36 isolates were collected. Height (08) Sporangia shape of P. infestans were obtain and 02 new different shape were pip form and oval to ellipsoid. Sporangia length/width ratio ranged from 1.62 to 2.18. Mating types A1 and A2 were present in the studied areas. Pathogenicity test on detached potato leaflets was positive with all the 36 isolates. The isolate HPBT02 from Tsela locality was more aggressive (P<0.05). MANATE variety was more susceptible. Conclusion: The study shows that mating types A1 and A2 of P. infestans exit in Cameroon and the morphology of sporangia varies according to the localities. Molecular characterization is needed.

Some insects cause high losses of the common bean during storage, namely, <i>Acanthoscelides obtectus</i> Say. Chemical insecticides are commonly used to control insects, but their overuse adversely affects the environment and consumers' health. There is, therefore, the need for an alternative control method. This study was aimed to evaluate the chemical characterization and insecticidal property of <i>Moringa oleifera</i> seed extract on the developmental stages of <i>A. obtectus</i> in stored beans. Three types of <i>M. oleifera</i> seed extracts, namely methanol, ethanol and acetone extracts, were used at doses of 12.5, 25 and 50 µl/ml each. HPLC-MS was used to characterize these extracts. The toxicity of extracts against the adults, the number of eggs and the viability rate of laid or emerged eggs of <i>A. obtectus</i> were evaluated. The results show that <i>M. oleifera</i> seed extract is rich in Hesperidin, Quinic acid, gallic acid, protocatechuic acid, 4-OH benzoic acid, cynaroside, isoquercitrin, cosmosiin, quercitrin, luteolin, naringenin, salicylic acid, Apigenin and Fumaric acid. The acetone extract, from day 2, showed a 100% mortality rate in all doses compared to about only 14% in the control treatment. The number of eggs laid in control (236.67) was higher than the null (0) in acetone treatment at 50 µl/ml. M. oleifera seed extracts contain chemical molecules. They significantly reduced the damage caused by <i>A. obtectus</i> on stored <i>P. vulgaris</i> grains. Therefore, they can be used as an alternative to chemicals for the protection of stored foodstuffs.

Alternatives to synthetic chemicals are undertaken against phytopathogens. The aim of this work is to evaluate the effect of seed extracts of Thevetia peruviana (Pers.) K. Schum. on Mycosphaerella fijiensis Morelet, fungus responsible for banana black leaf streak disease. Five extracts of T. peruviana, hexane extract (HE), ethyl acetate extract (EAE), acetone extract (AcE), methanol extract (ME) and aqueous extract (AqE), and a fungicide, Azoxystrobin were used. GC-MS of acetone extract was performed. Fifty (50) strains of M. fijiensis per sampling site were tested. Three concentrations of extracts 6.25 (C1), 12.5 (C2), and 25 (C3) μl/ml, a negative control (0 μl/ml) and 10 ppm of azoxystrobin were used for the tests. The MIC50 and MIC90 were determined. GC-MS showed chemical compounds with different molecular height such as acids, sugars, and esters. AcE and AqE significantly reduced M. fijiensis germ tube growth at C2 and C3 concentrations and with inhibition percentage respectively ranged of 60-90% and 40-80%. The growth levels of the germ tubes were above the strobilurin resistance threshold at Njombe and peasant plantation, ranging from 77.9% to 92.3%. AcE showed the same or superior efficacy as the fungicide used on conidial germination at all tested concentrations. The MIC50 totally reducing mycelial growth and conidial germination was 6.25 μl/ml. T. peruviana seeds extracts can be exploited in integrated pests management against M. fijiensis.

In Africa, rice is produced and is a source of food energy in most developing countries. But its cultivation faces to brown spot disease, caused by Bipolaris oryzae (Breda de Haan) Shoemaker, which is a serious seed-borne and seed transmitted disease of rice worldwide.The aim of this study was to screen rice varieties for resistance to brown spot disease in field conditions inYaoundé. A completely randomized Fisher block design with three repetitions was used during 2 growing seasons (2015 and 2016). Growth, yields and disease (incidence and severity) parameters were evaluated on four rice varieties (Nerica 3 and 8, White rice and Kamkou). Results show that height of the Nerica 8 variety (86.03cm) and the number of tillers of Kamkou variety (21.66) were significantly highest compared to others varieties (P<0.05) at 59 Days After Sowing (DAS). There was no significant difference on disease incidence for the different rice varieties at the end of rice plant cycle. However disease severity was lower on Nerica 3(2.71%) and Nerica8 (2.05%) varieties and higher on White variety (4.57%). Hence, Nerica 3 and 8 varieties were more tolerant to brown spot disease than others varieties. Overall, Nerica 3 (3.68 t ha-1) and Kamkou (3.51 t ha-1) varieties resulted in higher yields than white rice 28.93 t ha-1.