D. J. Soares

Additions to the mycobiota of the invasive weed Miconia calvescens (Melastomataceae)

Miconia calvescens (Melastomataceae) is a shrub or small tree native to the Neotropics that has become one of the worst invaders of forest ecosystems, particularly in Pacific islands such as Hawaii and French Polynesia. It has been a target for biological control for more than 10 y, both with arthropod and pathogen natural enemies. Until now Colletotrichum gloeosporioides f. sp. miconiae was the only organism to be used in biological control against this weed. This fungus was introduced both in Hawaii and in French Polynesia in the late 1990s/early 2000s, where it has caused some damage to the weed, but it became evident that additional agents are needed to achieve adequate control. Exploratory surveys for plant pathogens as potential biocontrol agents of M. calvescens were undertaken in Brazil, Costa Rica and Ecuador and yielded a diverse list of pathogens, including one phytoplasma, two nematodes, one oomycete and numerous fungi. A study including the description of five fungal species found attacking M. calvescens was published recently. Herein the following additional fungi also belonging to the mycobiota of M. calvescens are described: Hyalosphaera ornata sp. nov, Microsphaeropsis miconiae sp. nov., Myrothecium miconiae sp. nov., Phyllachora miconiiphila sp. nov., as well as Hyalosphaera miconiae, Lembosia melastomatum and Microsphaeropsis clidemiae, which are recorded here for the first time on this host. Although preliminary our observations of damage to M. calvescens caused by these seven fungal species did not indicate any potential for use in classical biological control.

First report of Gilbertella persicaria as the cause of soft rot of fruit of Syzygium cumini

A zygomycetous fungus causing fruit soft rot was found on Sygyzium cumini in Northeast Brazil. Based on morphological and phylogenetic analyses, the fungus was identified as Gilbertella persicaria. This is the first report of this fungus causing the decay of S. cumini fruit worldwide.

Natural infection of Acalypha hispida and Jatropha podagrica inflorescences by Amphobotrys ricini in Brazil.

Amphobotrys ricini is recorded for the first time causing natural blight on inflorescences of the ornamental euphorbiaceous hosts Acalypha hispida and Jatropha podagrica in Brazil.

First report of Asteridiella pittieri on golden dewdrop (Duranta repens var. aurea) in Brazil.

A black mildew caused by Asteridiella pittieri (Meliolales) was observed on the foliage of the ornamental species Duranta repens var. aurea (Verbenaceae) in the states of Minas Gerais and São Paulo, Brazil. This is the first record of this fungus in Brazil. Although the impact of the disease on the host is minimal, infected plants become unsightly and, therefore, worthless for horticultural purposes.

Pseudocercospora species on Piperaceae from Viçosa, Minas Gerais, Brazil

Three Pseudocercospora species were found associated with leaf spots on five different members of the family Piperaceae in a stretch of Atlantic rain forest in the municipality of Viçosa, Minas Gerais, Brazil. Pseudocercospora piperis is newly recorded on Piper crassinervium and Piper mollicomum. It was also found in association with Pothomorphe umbellata, which is already known to be a host. Pseudocercospora piperis-arborei sp. nov. and Pseudocercospora piperis-gigantifolii sp. nov. were recorded on Piper arboreum and Piper gigantifolium, respectively. These three species are fully described and illustrated in the present work.

Cercosporoid hyphomycetes associated with Tibouchina herbacea (Melastomataceae) in Brazil

A survey of fungal pathogens associated with cane tibouchina, Tibouchina herbacea (Melastomataceae), was conducted in the neotropics, concentrated in south and southeastern Brazil and aimed at finding potential biological control agents for this herbaceous invasive weed for introduction into Hawaii. Numerous fungal species were found, including five cercosporoid fungi. Four new taxa are described and illustrated here: Passalora tibouchinae, Pseudocercospora subsynnematosa, Pseudocercospora tibouchina-herbaceae and Pseudocercospora tibouchinicola. A phylogenetic analysis of the ITS and TEF-1α regions of the three new species of Pseudocercospora was conducted and confirmed their separation as distinct taxa as indicated by morphological and cultural features. Additionally, Cercospora apii is reported for the first time on T. herbacea. Among the species of fungi described in this study, two appear particularly promising for use in a biological control program because they were found to cause severe disease on T. herbacea: Passalora tibouchinae and Pseudocercospora subsynnematosa. Additional tests, including host-specificity screening, will be required in order to confirm this potential.

Epidemic spread of Puccinia hemerocallidis in Brazil

Since the first report of daylily rust (Puccinia hemerocallidis) in Brazil in the state of São Paulo in 2001, it spread during that decade and is now found in a very broad area encompassing central, northeastern, southern and southeastern Brazil. It is now regarded as one of the major disease problem for this popular ornamental. Events in Brazil were equivalent to those of the epidemic spread of P. hemerocallidis in the US which occurred around the same period.

First report of downy mildew on Plantago major caused by Peronospora alta in Brazil

Peronospora alta is recorded for the first time causing downy mildew on Plantago major (Plantaginaceae) in Brazil.

Condições de ambiente favoráveis à germinação e à infecção de Puccinia substriata var. penicillariae em diferentes cultivares de milheto pérola

The rust caused by Puccinia substriata var. penicillariae in Pearl millet (Pennisetum glaucum) induces yield losses in this forage crop. Considering the lack of information about this disease in Brazil, this research on its epidemiology has been carried out. The mean latency period, the frequency of infection process and size of lesions on four genotypes of pearl millet (Pennisetum glaucum) ENA 1, Composto II, BRS 1501 and HKP were evaluated in the greenhouse. In vitro, the germination of the urediniospores was monitored at different temperatures (10, 15, 20 and 25oC), with or without light. After this, the infection process was compared for the genotypes Guerguera, Souna III, BRS 1501 and ENA 1, in a growth chamber, with the leaf wetting time of 0, 1, 2, 4, 8 and 12 hours, with or without light, and in greenhouse, on the genotypes ENA 1, Guerguera and Souna III, with the leaf wetting times of 3/4, 1, 2, 4, 6 and 8 hours. A mean latency period for pearl millet rust between 10 and 12 days was shown, and the urediniospores germinated in a wide range of temperatures, from 10 to 25oC, with or without light, with a maximum germination at 17.5oC in the dark. In these conditions, the germination of first spores initiated for less than 45 min at a maximum percentage of 88.2%, with 1.7 h of incubation. Leaf infection can also start after 45 min of leaf wetting after inoculation, but there is a beneficial effect of dark and longer leaf wetting time.

First report of downy mildew onPlantago major caused byPeronospora alta in Brazil

Peronospora alta is recorded for the first time causing downy mildew onPlantago major (Plantaginaceae) in Brazil.