Phytotoxic effects of metabolites from Alternaria euphorbiicola against its host plant Euphorbia heterophylla

A bioassay-guided fractionation of culture filtrates of the fungus Alternaria euphorbiicola, a pathogen of the weed Euphorbia heterophylla, led to the isolation of anhydromevalonolactone (1), tyrosol (2), (R)-( - )-mevalonolactone (3), and cycloglycylproline (4). When tested on the punctured leaves of the host plant, these compounds produced bleached lesions with dark brown margins at concentrations as low as 80 µM. When tested on the leaves of other relevant weeds, only cycloglycylproline showed selective activity against E. heterophylla. This is the first report on the isolation of phytotoxins from A. euphorbiicola and on the phytotoxicity of anhydromevalonolactone, (R)-( - )-mevalonolactone, and cycloglycylproline

NOVAS OPÇÕES DE SUBSTRATOS PARA O CULTIVO DE Cyrtopodium cardiochilum (ORCHIDACEAE)

O presente trabalho teve como objetivo avaliar o efeito de diferentes substratos no cultivo da espécie Cyrtopodium cardiochilum (Orchidaceae). As mudas foram cultivadas em vasos de polietileno, em casa de vegetação com tela de sombreamento de polipropileno de 60% de luminosidade. Os tratamentos constituíram-se de brita de gnaisse (granulometria variando de 8 15 mm), argila expandida (15 22 mm de diâmetro), seixo rolado (8 15 mm), casca de coco em cubos (coxim) e vermiculita. Foram analisadas também as combinações de brita e argila expandida, brita e seixo, argila expandida e seixo, na proporção 1:1 (v/v); brita, argila expandida e seixo na proporção 1:1:1 (v/v/v); e brita, argila expandida, seixo e vermiculita na proporção 1:1:1:1 (v/v/v/v). Após seis meses de instalação do experimento foram avaliadas as seguintes variáveis: altura das plantas, diâmetro dos pseudobulbos, número de folhas, produção de massa de matéria seca total (MST), da parte aérea (MSPA) e do sistema radicular (MSR). Utilizou-se o delineamento experimental em blocos casualizados, composto por nove tratamentos e oito repetições. Não houve diferença entre os tratamentos para: altura de planta, número de folhas, diâmetro dos pseudobulbos e MSR. Para a MSPA e MST observou-se diferença entre os substratos, com destaque para o tratamento argila expandida + brita de gnaisse. Conclui-se que todos os substratos testados podem ser utilizados no cultivo de C. cardiochilum, destacando-se o substrato argila expandida + brita de gnaisse na proporção de 1:1 (v/v)

Pseudocercospora piperis associated with leaf spots on Piper aduncum in Brazil

Piper aduncum (Piperaceae) is a neotropical plant that has been widely exploited as a medicinal plant in its native range but has recently become an important invasive plant species in Papua New Guinea. A cercosporoid fungus was recently found associated with leaf spots on this plant in the Amazon. The morphology of the fungus is typical of Pseudocercospora piperis, a fungus that has never been recorded on this host species in Brazil. © 2013 Australasian Plant Pathology Society Inc

The mycobiota of the weed Mikania micrantha in southern Brazil with particular reference to fungal pathogens for biological control

A survey of the fungi associated with the tropical weed Mikania micrantha was conducted during 1988 and 1989 in part of its native range in southern Brazil. Sampling was concentrated mainly in the state of Rio de Janeiro, covering 70 sites in different climatic or ecological zones. Nine species were identified, including the recently described downy mildew species Basidiophora montana and the previously undescribed Mycosphaerella mikania-micranthae sp. nov. with its anamorph Septoria mikania-micranthae. Asperisporium mikaniae comb. nov., Asperisporium mikaniigena comb. nov., Pseudocercospora plunketii comb. nov., and Cercospora mikaniacola are new records for Brazil. Field observations indicate that Basidiophora montana has potential as a classical biological control agent of the weed in Old World subtropical or montane climates, whilst Mycosphaerella mikania-micranthae and the microcyclic rust Puccinia spegazzinii appear to be equally damaging to the host but to have a wider climatic range and thus are highly promising agents for introduction throughout the Palaeotropics

Petal spotting of hydrangea flowers caused by Corynespora cassiicola: old pathogen — new disease

Diseased hydrangeas (Hydrangea macrophylla) were found growing in gardens of highland localities of the states of Rio de Janeiro and Minas Gerais (Brazil). Distinct multiple purple spots in flowers that gave an unsightly chicken-poxed (varicella-like) appearance to the inflorescences were found along with leaf necrosis. The severity of the disease seriously impairs the ornamental value of this highly popular garden plant. The fungus Corynespora cassiicola was found associated with leaf and flower lesions. Brush inoculation of leaves with conidia obtained from a flower isolate resulted in the formation of leaf spots identical to the ones observed in the field. Although this fungus is known to be a pathogen of hydrangea foliage this is the first time the fungus is recognised to cause a flower disease on this host. The flower disease, here called petal spotting of hydrangea, and the fungus involved are described and illustrated

First record of Botryosphaeria ribis associated with leaf spots on Magnolia aff. candollei in Brazil

A leaf spot disease was observed attacking some Magnolia aff. candollei plants grown in a private garden in the city of Rio de Janeiro, RJ, Brazil. Such leaf spots coalesced and led to extensive blight of foliage. A fungus was clearly associated to the disease symptoms and was identified as Botryosphaeria ribis. Its anamorph, Fusicoccum ribis, was also present, although less abundant than the teleomorph. This is first report of this fungus on this host in Brazil and the first record of any fungal disease on a member of the genus Magnolia in Brazil

Passalora gochnatiicola sp. nov. on Gochnatia amplexifolia from Serra do Cipó, MG, Brazil

The leaf-spotting hyphomycete Passalora gochnatiicola sp. nov., collected on Gochnatia amplexifolia (Gardner) Cabrera (Asteraceae: Mutisieae) in the 'campos rupestres' of Serra do Cipó (Minas Gerais State, Brazil), is described, illustrated, discussed and compared with allied species

Passalora gochnatiicola sp. nov. on Gochnatia amplexifolia from Serra do Cip\uf3, MG, Brazil

The leaf-spotting hyphomycete Passalora gochnatiicola sp. nov., collected on Gochnatia amplexifolia (Gardner) Cabrera (Asteraceae: Mutisieae) in the 'campos rupestres' of Serra do Cipó (Minas Gerais State, Brazil), is described, illustrated, discussed and compared with allied species.O hifomiceto causador de mancha foliar Passalora gochnatiicola sp. nov., coletado em Gochnatia amplexifolia (Gardner) Cabrera (Asteraceae: Mutisieae) nos campos rupestres da Serra do Cipó (Minas Gerais, Brasil), é descrito, ilustrado, discutido e comparado com espécies afins