Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

First report of Puccinia psidii caused rust disease epiphytotic on the invasive shrub Rhodomyrtus tomentosa in Florida.

Abstract

Rhodomyrtus tomentosa (downy-rose myrtle, family: Myrtaceae), of South Asian origin, is an invasive shrub that has formed monotypic stands in Florida, USA. During the winter and spring of 2010 through 2012, a rust disease of epiphytotic proportion was observed on young foliage, stem terminals, and immature fruits of this shrub in natural areas of Martin and Lee counties, Florida. Expanding leaves and succulent stems developed chlorotic flecks on the surface that developed into pustules and ruptured to discharge urediniospores. Symptomatic leaves and stems developed severe necrotic spots and resulted in tissue distortion, defoliation, and stem dieback. Based on symptoms, urediniospore morphology and pathogenicity tests, the causal agent was identified as Puccinia psidii. This identification was confirmed by a GenBank BLAST of internal transcribed spacer sequences (Accession Nos. KC607876 and KC607877) that showed 99% identity with 42 sequences of P. psidii from diverse host species and locations. This is thought to be the first confirmed report of P. psidii epiphytotic on downy-rose myrtle populations in Florida.