Fungi associated with a dry invasive white patches on trunks of economic fruit trees in south-west Nigeria

Abstract

An unprecedented number of fungal and fungal-like diseases are the main threat to the diversity and productivity of economic fruit trees in southwest Nigeria. The objective of this study was to investigate the fungi associated with dry invasive whitish patches, noticeable on trunks and branches of cocoa (Theobroma cacao), kola-nut (Cola spp.) and sweet orange (Citrus sinensis) trees prevalent in southwest Nigeria. A total of 108 whitish patch scraped samples were aseptically obtained from the affected cocoa, kola-nut and sweet orange trees in Osogbo, Ife, Ejigbo and Ilesha plantations in southwest Nigeria for this study. Viable fungal populations, were determined using the spread-plate techniques; and pure fungal isolates were identified through their morphological appearance, microscopic features and sporing structures. Mean viable fungal count in the samples ranged from 3.85 x 10 4 ± 0.00 to 9.75 x 10 3 ± 0.00 CFU g-1. Viable fungal counts were significantly different (P < 0.05) between fruit tree species and across locations. A total of 52 fungal species belonging to 21 genera were isolated, with Aspergillus and Penicilliumas predominating and occurring at 23 and 17%, respectively. Other isolated genera included seven from cocoa trees; ten from kola-nut trees and five from sweet orange trees. There is need for appropriate control strategies to prevent further spread in contiguous plantations.