The Eugenia myrcianthes fruit can be consumed in natural or processed form (jellies and juices) (Infante et al., 2016). In 2019, in the UTFPR, Dois Vizinhos city, Paraná State - Brazil, yellow uredinias epiphyllous were observed on the tissue surface (leaves, stems, flowers, and fruit) of twenty-one trees of E. myrcianthes, which resembled structures typical of Myrtaceae rust. All colonized tissues showed necrotic lesions that varied in size and shape, causing death, especially in fruit. In the orchard, the fungus affects 50% to 95% yield. Fruit (10) and leaves (20) with symptoms were collected from 11 trees from different positions in the orchard. Infected tissues were incubated (25°C and 12-hour photoperiod) for 7 days to induce sporulation. The epiphyllous uredinia, united in small groups with hyaline and globose urediniospores were observed and presented equinulate ornaments and germinated pores in the subequatorial and inordinate positions (De Pieri, 2012; Cummins; Hiratsuka, 2003) (mean 14.00 μm × 21.12 μm, n = 30) similar to the morphological characteristics of the Austropuccinia genus described by Young (2019). The identification of 10 samples (fruit and leaf) of the pathogen taken from infected parts of the trees was confirmed. For molecular identification, the internal transcribed spacer (ITS) region was amplified by polymerase chain reaction (White et al. 1990) and sequenced. Phylogenetic analyses using Bayesian inference grouped the strain from Eugenia myrcianthes with the epitype species of Austropuccinia psidii (Beenken, 2017), with a high posterior probability (0.99). The sequences of one representative strain (Emg1) were submitted to GenBank (OM948983). For pathogenicity tests, three healthy branches containing 20 leaves were sprayed with 3.0 mL of urediniospores suspension (105) of Emg1 and covered with a plastic bag in the orchard (25ºC). Sterile distilled water was used as a control. Three replications (pathogen and control) were performed on different trees. After 6 days, symptoms appeared and their morphological features were similar to those previously reported. Control branches did not present fungal growth. The inoculation test was repeated again, confirming symptoms such as uredinia and urediniospores, characteristic of the disease. This is the first report of the incidence of A. psidii infection in E. myrcianthes trees in Brazil, causing rust, necrosis, and senescence in fruit, leaves, flowers, and stems. The rust on E. myrcianthes causes destructive damage to yield, as the pathogen causes fruit to rot and drop prematurely.
Keywords: Crop Type; Fruit; Native; Rust.