Main Diseases of Pepper (Piper nigrum L.) in the Localities of Njombe-Penja (Cameroon)

Piper nigrum is an important crop. However, this crop is very vulnerable to pests and diseases, which can cause a drop in production if no control methods are applied. The general objective of our study is to contribute to a better understanding of diseases and the various associated pests and diseases in the study sites (Njombe and Penja). To achieve this objective, the main diseases of pepper in the field were identified and described. In each site, four quadrats of twenty pepper plants out of twenty were planted; the different diseases were identified and described according to their characteristic symptoms. Their incidence and severity were assessed along the diagonal of each quadrat. The pathogens responsible for these diseases were characterized macroscopically and microscopically using several identification keys. The results showed that in both study areas, several symptoms were observed, including necrosis, scorching, diffuse spots, sparse spots, blistering on the leaves and leaf yellowing corresponding to diseases such as: Anthracnose, Cercosporiosis, Mildew, Rust, Galle and slow decline. In both sites, the incidence varied from 65 to 100% and the severity from 25 to 75%. In the Petri dishes, the colour of the mycelium varied between black, white, pink and brown and had a milky, cottony appearance. Microscopically, the shape of the spores varied from round, oblong, fusiform, reniform and falciform. Some hyphae were septate and others were non-septate. Species of fungi such as Colletotrichum gloeosporioides, C. necator, Cercospora sp., F. solani, F. oxysporum, Rhizoctonia sp. and Cephaleurus virescens were identified as being responsible for these diseases. Knowledge of these pathogens could contribute to the development of more environmentally-friendly control methods.