Clonostachys, Trichoderma, and Trichothecium species associated with myrtle rust (Austropuccinia psidii) in Brazil

Nívia Maria Pereira da Silva, Robert Weingart Barreto & Gleiber Quintão Furtado

Sydowia 78: 201-220

Published online on January 12th, 2026

Austropuccinia psidii, the causal agent of myrtle rust (MR), is a neotropical member of the Pucciniales, is the worst pathogen of guava and an important pathogen of young eucalypt in Brazil. It has spread from its native neotropical range and, after detected in Hawaii (2005) spread fast through the tropics and subtropics and became a major threat to native and cultivated Myrtaceae. It has a broad host-range, in contrast with most Pucciniales, including numerous forest species endemic to Australia, New Zealand and Hawaii. Classical biological control is considered the only sustainable option of management of exotic invasive species in unmanaged ecosystems. However, in the case of MR, there are few accounts of natural enemies which might be deployed against it from its neotropical range. Pioneering surveys of fungi associated with A. psidii have been recently started in Brazil. A significant diversity of fungi has been found on A. psidii pustules. The identity of these fungi is being clarified through a combination of morphological information and multilocus phylogenetic analyses (ITS, LSU, EF1, CAL and TUB2). Here, the taxonomic placement of three of those fungi was elucidated, namely: Clonostachys farinosa, Trichoderma koningiopsis and Trichothecium roseum. None of these species has ever been recorded in association with A. psidii.

Keywords: filamentous fungi, Hypocreales, mycoparasitism, polyphasic taxonomy.

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