Assessment of nematicidal properties and phytochemical screening of neem seed formulations using Radopholus similis, parasitic nematode of plantain in Cameroon

Phytoparasitic nematodes of banana and plantain make one of the major constraints to sustainable banana and plantain production. The burrowing nematode, Radopholus similis, common in Cameroon is of particular importance where most smallholder farmers are unaware of this “hidden enemy”. In intensive plantain plantations, nematicides are often used as a primary means of control. Despite their efficacy, chemical pesticides are harmful to the environment and human health. The objective of this study was to assess the nematicidal properties of four neem seed formulations (raw neem seed powder (NSP); organic, watery and essential oil extracts) and to determine the phytochemical properties of these extracts. Alkaloids, saponins, triterpens and steroids were found in all three extracts, tannins in the organic and essential oils extracts and phenols only in the essential oils extract. Using five different concentrations of each of the three extracts as well as NSP, the nematicidal properties of all four formulations was confirmed. The NSP killed 100% of all nematodes at the lowest concentration tested, 10 μg ml⁻¹, after 48 h. The in vivo test using two plantain varieties, Essong and Big Ebanga showed that all neem seed formulations increased plant growth and reduced nematode populations significantly when compared with the control. Since NSP seems to perform as well or even better than the extracts, it could provide farmers with a simple, low cost alternative for the control of banana and plantain nematodes.     

Cocoa-based agroforestry system dynamics and trends in the Akongo subregion of central Cameroon

Cocoa is a major crop and income source for most farmers and rural households in the Centre, South and South-West regions of Cameroon, where cocoa is generally produced in agroforestry systems. In this country, cocoa-based agroforestry systems (CBAFS) are undergoing multiple changes alongside the rapid changes underway in the natural, economic and socio-political conditions. This study—carried out in the Akongo subregion in central Cameroon—was designed to gain insight into the CBAFS trends and dynamics in the light of those multiple changes. This semi-structured socioeconomic survey involved interviews and direct observations at plot, farm, household and village scales. Overall, forty cocoa growers from ten villages were interviewed and then fifteen cocoa plots were characterized on the basis of the survey findings. They revealed that cocoa was the major crop in this study area, with cocoa plantations occupying three quarters of the total farming area. Three types of CBAFS were identified, which differed according to their vegetation structure, management practices and age of the plantations. Dynamics affecting the structural characteristics and the spatial extension of these systems emerged and were intimately linked to the dynamics of the cocoa farmer population in relation to their context.