Identification and in vitro control of spot disease of sweet orange fruit caused by Colletotrichum gleoesporiodes

Abstract

Citrus is an important cash crop which contributes significantly to the income of millions of smallholder farmers in Nigeria as the fruits are grown largely for local consumption. Citrus production is limited by low fruit yield and fruit blemishes caused by diseases and pests. Fruit spot is a disease of great economic importance to citrus production in Nigeria and constitutes a threat to citrus cultivation. The causal pathogen of citrus fruit spot disease was isolated from infected fruits obtained from National Horticultural Research Institute (NIHORT) orchard, Ibadan and from farmers' fields. Efficacy of three fungicides namely Z-force (a.i 80% mancozeb), Forcelet (a.i 50% carbendazim) and Funguforce (63% mancozeb + 12.5% carbendazim) at a single dose were tested. Of the four pathogens isolated from diseased fruits, Colletotrichum gloeosporioides had the highest frequency of occurrence (80%) and a pathogenicity test revealed this specie as the causal pathogen of citrus fruit spot. All the fungicides tested had total inhibition (100%) on the mycelial growth of the fruit spot pathogen in vitro at the concentrations that were used.