Mycobiota of the weed Tradescantia fluminensis in its native range in Brazil with particular reference to classical biological control

Abstract

Tradescantia fluminensis [Commelinaceae] (common name wandering Jew or trad), is a native Brazilian herbaceous plant, which has been introduced to be used as an ornamental in many warm areas of the world. In New Zealand and other countries it has become an aggressive invader of natural ecosystems, causing serious environmental disturbances and threatening biodiversity. Surveys of pathogen and insect natural enemies of T. fluminensis were conducted over several years in Brazil to identify potential candidates for use as classical biological control agents in New Zealand. The surveys found seven pathogenic fungi associated with T. fluminensis and related Tradescantia species: Cercospora apii (leaf spot), Rhizoctonia solani (leaf blight), Sclerotium rolfsii (crown rot) and Uromyces commelinae (rust), and three novel species described in this paper: Ceratobasidium tradescantiae sp. nov. (web blight), Colletotrichum riograndense sp. nov. (anthracnose) and Kordyana brasiliensis sp. nov. (white smut-like disease). Observations of damage in the field and expected host-range suggest that K. brasiliensis and U. commelinae have the highest potential for use as classical biological control agents.