Thielaviopsis musarum causes postharvest crown and fruit rot of banana in Northeastern Brazil

Abstract

Crown rot is an important postharvest disease of banana fruit caused by a fungal complex. The development of these microorganisms in the banana favors rot of the fruit and crown, affecting fruit quality and rendering the fruit unsafe to eat. Fungi that cause postharvest rot include species of the complex Thielaviopsis paradoxa. In March 2015, symptoms of crown rot were observed in banana grown in the state of Piauí, Northeastern Brazil. The fruits exhibited rot, usually with signs of a dark gray mycelium; fruits at an advanced stage of rot broke from the stem. Microscopic analysis revealed the presence of primary and secondary conidia as well as aleurioconidia, typical for Thielaviopsis spp.. The sexual phase was not observed. The ITS and TEF1-α genes were sequenced and subjected to phylogenetic analysis; consequently, the isolates were identified as Thielaviopsis musarum. In inoculated fruits, the fungus caused black rot, followed by a browning and softening of the pulp. This is the first record of postharvest rot in banana caused by T. musarum in Brazil.