Identification of pathogens and monitoring methods for leaf spots disease of shea tree (Vitellaria paradoxa Gaertn. C. F.) in the cropping systems of Komki Ipala (Burkina Faso)

Abstract

Vitellaria paradoxa is a multipurpose plant species which unfortunately is under multiple pressures causing damages to the plant. This study was to develop methods for monitoring causative agents of shea trees leaf spots in Burkina Faso. An inventory of shea tree individuals and a characterization of leaf spots were performed in Tampoussoumdi, Burkina Faso. Thus, twelve (12) plots of 100 m x 50 m were set up in fallows and fields for identifying all shea trees. Pathogens were also identified by isolated infected leaves fragments of on PDA medium. Isolates were purified and observed under a microscope (X40). As to develop pathogens monitoring methods, three mycorrhizal fungi (yac, fada, Ga) were used to inoculate shea trees cultivated in greenhouse. After two months, inoculated plant leaves were sprayed with prepared isolates of identified pathogens and infection occurrence was checked daily. Results revealed that infection occurred only in unburned fallows and concerned 65% of the shea tree communities. Fungi were found to be responsible for these infections and three species were identified including Fusarium moniliforme, Pestalotia guepini and Phoma sorghina. Results also showed that mycorrhizae can inhibit pathogens growth partially or totally. Their potential use could help controlling the leaf spots disease in shea parks.