Pathogenicity and Control of Foliar Endophytic Fungi of Citrus sinensis L. (Sweet Orange) Using Plant Extracts

Abstract

Endophytic colonisation of plant tissues by microbes is an important determinant of plant health and productivity. A study was carried out to evaluate the pathogenicity and control of endophytic fungi isolated from citrus leaves in Lafia. Endophytic fungi recovered from citrus leaves were morphologically identified and subjected to pathogenicity tests. Pathogenic endophytes selected from the pathogenicity test were administered with different concentrations of aqueous and ethanolic extracts of Carica papaya and Azadirachta indica. Results revealed that the endophytic fungi belonged to three species: Colletotrichum asianum, Colletotrichum nymphaeae, Talaromyces sp., Talaromyces funiculosus, and Bipolaris sp. Of the identified endophytic fungi, C. asianum was the most prevalent (61.82%), followed by C. nymphaeae (32.73%), while T. funiculosus, Talaromyces sp., and Bipolaris sp. all had 1.82% occurrence within the studied area. Pathogenicity tests showed that C. asianum was the most pathogenic (13.30%), followed by C. nymphaeae (6.67%) (P≥0.05). Tests of fungicidal activity of Carica papaya and Azadirachta indica leaf extracts against the pathogens showed that aqueous extracts of Carica papaya were most potent against the test organisms, inhibiting at least 93.92% of the test organisms at all tested concentrations. Differences in growth inhibition of the pathogens by the extracts were significant (P<0.05). The study revealed that Colletotrichum asianum and C. nymphaeae are the primary pathogenic endophytes of citrus leaves in Lafia, while aqueous leaf extracts of Carica papaya possess exceptional antifungal activity against these pathogens, offering promising potential as an eco-friendly bio-fungicide for citrus disease management.