Mycofloral Pathogen Associated with Anthracnose of Mango in Yola, Adamawa State, Nigeria

Abstract

Mango fruits sold in Yola and the environs exhibit symptoms of the anthracnose disease. Therefore, the present study focused on isolation, characterization, identification and pathogenicity testing of fungal pathogen associated with the disease in Yola, Adamawa State, Northeastern Nigeria. Mango fruits and leaves that were naturally infected with anthracnose were purposefully sampled from home gardens, farms, and marketplaces. The naturally infected plant parts showing the disease symptoms were taken and moved to the laboratory for direct isolation, characterization, identification of the causal pathogen and pathogenicity testing of fungal isolates. 5 mm2 pieces of symptomatic crown tissue were excited from the advancing lesion margins, sterilized with 70% ethanol for 2 min, then with 10% sodium hypochlorite for 1 min and lastly rinsed in 3 changes of sterile distilled water. The sterilized lesion cut piece were placed on each petri dish containing the solidified PDA. A plug of sporulating mycelia was taken from each plate, mixed with 2 drops of Lactophenol cotton blue “RM” stain, (Biolution Resources), covered with a slide cover, was used for determining spore shape and number of septa. Colonies having same features were grouped together and identified as same species. Nineteen fungal colonies from three genera were obtained from the sampled naturally infected diseased plant parts. They are; Aspergillus niger, Rhizopus oryzae, and Colletotrichum gloeosporioides were recognized based the morphological similarities; color, texture, spore shape and size, and number of septa. The frequency of C. gloeosporioides was highest (66.67%) (77.78%) in both infected fruits and leaves, followed by A. niger (11.11% and 20.00%) and R. oryzae (22.22% and 10%), respectively. Of the three isolates, only one (C. gloeosporioides), was found to be pathogenic, by its ability to incite anthracnose disease on the respective healthy plant part.