Identification and Characterization of Fungi Causing Thread Blight Diseases on Cacao in Ghana.

Theobroma cacao (chocolate tree) is currently under serious threat from thread blight disease (TBD), which has been attributed to the causal agent Marasmiellus scandens in other regions of the world. TBD in Ghana has similar symptomology but variable signs. This study sought to determine whether TBD in Ghana was caused by a single agent and whether Marasmiellus scandens was a significant agent of TBD. Forty-eight isolates were collected from eight geographical locations in Ghana for morphological and molecular characterization. Disease signs occurred as vegetative rhizomorphs or hyphal aggregates, which were classified into five morphotypes: A, abundant thin, black, "horse hair"-type rhizomorphs; B, scattered brown rhizomorphs; C, whitish to brownish-white; D, faint cream or dull white; and E, aggregates of shiny or silky white hyphae. Sequencing and analyses of three loci-the internal transcribed spacer region of the nuclear ribosomal repeat, nuclear large subunit, and mitochondrial small subunit-detected four species, all members of the Marasmiaceae, causing TBD-like disease. These were identified as Marasmius crinis-equi (morphotype A), Marasmius tenuissimus (morphotypes B and C), Marasmiellus palmivorus (morphotype E), and Marasmiellus scandens (morphotype D). Marasmius tenuissimus, the most frequently isolated TBD fungus in this study, is primarily an Asian fungus and not previously associated with diseases of cacao. Marasmiellus palmivorus, the second most frequently isolated fungus, is a pan-tropical pathogen with a broad host range; this is the first report of the fungus causing TBD on cacao. Marasmius crinis-equi also has a broad pan-tropical distribution and host range and causes thread blight on several tropical tree crops. Surprisingly, Marasmiellus scandens, the most frequently cited agent of TBD in cacao, made up only 8% of the isolates.

Chemical constituents and antimicrobial activity of medicinal plants from Ghana: Cassia sieberiana, Haematostaphis barteri, Mitragyna inermis and Pseudocedrela kotschyi.

The antimicrobial activity of the sequential n-hexane, acetone and 50% aqueous methanol extracts of leaves, stem bark and roots of four species of medicinal plants, Cassia sieberiana DC. (Leguminosae), Haematostaphis barteri Hook. f. (Anacardiaceae), Mitragyna inermis (Willd.) O. Kuntze (Rubiaceae) and Pseudocedrela kotschyi (Schweinf.) Harms (Meliaceae), from Ghana were tested against Bacillus subtilis, Pseudomonas syringae and Cladosporium herbarum using TLC direct-autobiographic methods. Extracts from leaves, stem bark and roots of the four species gave a positive result against at least one test organism. Twelve of the 36 extracts were active against B. subtilis, four extracts were active against P. syringae and six were active against C. herbarum. Preliminary chemical analysis revealed the presence of flavonoids, stilbenes and alkaloids. This is the first report of a stilbene from the Anacardiaceae.

Ethnobotanical study of some Ghanaian anti-malarial plants.

An ethnobotanical study was conducted in the Wechiau Community Hippopotamus Sanctuary area in Ghana, through interviews and quadrate studies, to investigate the range and abundance of species used in the treatment of malaria. Forty-one species belonging to 17 families were encountered during the study. Of the 17 families studied Leguminosae and Anacardiaceae predominated in terms of number of species used to treat malaria. Eight plant species namely, Afraegle paniculata (Rutaceae), Haematostaphis barteri (Anacardiaceae), Indigo era pulchra (Leguminosae), Monanthotaxis sp. (Annonaceae), Ozoroa insignis (Anacardiaceae), Strychnos innocua (Loganiaceae), Strychnos spinosa (Loganiaceae) and Xeroderris stuhlmannii (Leguminosae) have not previously been documented for the treatment of malaria in Ghana. The results are discussed and recommendations made for future research to support the conservation and sustainable harvesting of the species reported to have medicinal properties.