Identification and Characterizations of Pathogenic Fungal Species Associated with Symptoms of Cassava Anthracnose in Ivory Coast

Abstract

Cassava anthracnose is a plant disease that affects cassava stems, petioles and fruits. The aim of this study was to analyze the diversity of cassava anthracnose symptoms in Ivory Coast and then to identify and characterize the associated fungal genera. Surveys were carried out in all agricultural zones of the country from July to November, in 2014, 2015, 2016 and 2017. Infected samples consisting of stems cut with a small number of superficial cankers (0.3%), distorted stems (25.77%), and necrotic stems and petioles (65.18%) were collected. Also, withered and dried apical buds (8.76%) were harvested. Fungal pathogens derived from samples were Colletotrichum gloeosporioides (35.08%), Fusarium sp. (27.19%) and Botrytis sp. (19.73%) genera and undetermined strains (17.98%). Genera were characterized by morphological and microscopic characteristics. Parasitic pressure increased to 80 and 100% respectively for Botrytis sp. genus and Colletotrichum gloeosporioides and Fusarium sp genera. Fungal genera have caused lesions on stem and petioles in green house with diameters sizes 46, 71 and 72 mm respectively for genera Botrytis sp, Fusarium sp and Colletotrichum gloeosporioides. Aggressiveness index of Botrytis sp. genus was 3 and 4 respectively for Colletotrichum gloeosporioides and Fusarium sp. genera. The mycoflora of cassava aerial organs alteration, linked to the symptoms of anthracnose, is composed of genera of great economic importance and scientific interest.