Eucalyptus plantations cover approximately 5.1 million hectares of Brazil, an area that will likely increase given the demand for natural products from planted forests. In recent years, anthracnose diseases have been frequently found on eucalyptus in Brazilian nurseries. In 2012, rooted mini-cuttings of clones of E. urophylla x E. grandis ("urograndis") exhibiting leaf spot and stem girdling symptoms were collected from nurseries in the Brazilian states of Pará and Minas Gerais, and cultures of Colletotrichum were obtained from the lesions. The isolates were initially identified to species of the C. gloeosporioides species complex, according to searches of the Q-bank Fungi database with the DNA sequences of their internal transcribed spacer (ITS) regions. Subsequent phylogenetic analysis of the β-tubulin (TUB2) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) regions, combined with morphological characterization, allowed us to conclude that the fungus belongs to C. theobromicola. Conidial suspension sprayed on "urograndis" clone plants induced similar symptoms as those found under natural conditions. Re-isolation of the fungus from symptomatic plants fulfilled the Koch´s postulate. To our knowledge, this is the first report of C. theobromicola in Brazil.

In this study the susceptibility of different genotypes of gladiolus (Gladiolus callianthus and the genotypes of G. grandiflorum T-704, Red Beauty, Tradehorn, Verônica, Amsterdam, Yester Gold, and Rose Friendship) was evaluated and correlated with the development of Curvularia gladioli infective structures. The plants were inoculated with a 3 x 10(4) conidial suspension of the pathogen, and the severity of infection was assessed eight days after inoculation. Leaf samples of G. callianthus and G. grandiflorum vars. Amsterdam, Red Beauty, and T-704 were collected 24 hours after inoculation. They were cleared and the rates of spore germination and appressorium formation of C. gladioli were quantified. G. grandiflorum vars. T-704 and Red Beauty were the most susceptible genotypes, followed by G. callianthus and G. grandiflorum var. Tradehorn. The remaining genotypes did not differentiate among them. No differences related to the conidial germination (93.5%) were found for the genotypes. However, the highest values for appressorium formation were observed for G. callianthus (66.5%) and G. grandiflorus var. Amsterdam (55.7%), and the lowest values were observed for T-704 (32.4%). Thus, appressorium formation of C. gladioli was higher on leaf surfaces of resistant genotypes.

A ferrugem asiática, causada pelo fungo Phakopsora pachyrhizi, apresenta-se como um dos mais graves problemas fitossanitários da cultura da soja no Brasil, principalmente por não existirem, até o presente momento, cultivares com níveis de resistência satisfatórios. Objetivou-se estudar a influência da luminosidade e da camada de cera das superfícies foliares na infecção de folhas de soja por P. pachyrhizi. A superfície adaxial ou abaxial de folíolos do primeiro trifólio de plantas da cultivar BRS 154, estádio fenológico V2, foi inoculada com suspensão de 10(5) urediniósporos/mL-1. As plantas foram mantidas por 24 horas em câmara úmida e temperatura de 23ºC, sob luz ou escuro, em delineamento fatorial. Posteriormente, permaneceram 14 dias em fotoperíodo de 12 horas, sendo em seguida avaliada a densidade de lesões e a severidade da doença. Em um segundo experimento, avaliou-se in vitro , no escuro e na luz, a porcentagem de germinação de urediniósporos e de formação de apressórios. As camadas de cera adaxial e abaxial dos folíolos foram analisadas quantitativamente (extrações com clorofórmio) e estruturalmente (microscopia eletrônica de varredura). A densidade de lesões e a severidade foram maiores quando se inoculou a superfície adaxial de plantas incubadas no escuro, sem interação significativa entre os fatores. A germinação dos esporos no escuro (40,7%) foi significativamente superior à germinação na luz (28,5%). O mesmo ocorreu para a formação de apressórios, no escuro (24,7%) e na luz (12,8%). A quantidade e a estrutura das ceras epicuticulares não apresentaram diferenças entre as duas superfícies.

Asian rust, caused by the fungus Phakopsora pachyrhizi, is one of the most serious phytosanitary problems of soybean in Brazil, especially because no cultivars with satisfactory resistance levels as yet exist. The objective of this study was to evaluate the influence of luminosity and of leaf epicuticular wax on the infection of soybean by P. pachyrhizi. The adaxial and abaxial leaflet surfaces of the first trifoliate leaf from cultivar BRS 154, phenological stage V2, were inoculated with a suspension of 10(5) uredospores/mL. The plants were kept for 24 hours in a humid chamber at temperature of 23ºC, in light or dark conditions, using a factorial design. Subsequently, the plants were maintained for 14 days under a 12-hour photoperiod. The disease severity and density were evaluated. For in vitro experiments, in light or dark conditions, the evaluation was done in terms of uredospore germination and appressorium formation. The wax content of adaxial and abaxial leaflets was analyzed quantitatively using chloroform extraction and ultrastructurally using scanning electron microscope. Higher density and severity were observed when the adaxial surface was inoculated, with later incubation of the plants in the dark, with no significant interaction between these factors. Spore germination in the dark (40.7%) was statistically different from spore germination in the light (28.5%). The same effect was observed with appressorium formation, in the dark (24.7%) and in the light (12.8%). The quantity and the ultrastructural aspects of epicuticular wax content did not show differences between the adaxial and abaxial surfaces; nor did they show any effect on infection by Phakopsora pachyrhizi in the soybean cultivar studied.