Studies on the eucalyptus leaf disease complex in Portugal

Native from south eastern Australia, Eucalyptus globulus is the main species in eucalypts plantations in Portugal. The most serious foliar disease in eucalypt plantations is linked to Mycosphaerella senso lato, which affects young trees in the juvenile phase foliage causing leaf necrosis. This disease results in reduced growth rate of the host and lower wood volume, thus causing significant productivity losses. The most common name for this disease was Mycosphaerella Leaf Disease that became inappropriate when most of the pathogens on eucalypts were re-distributed into several genera. The term "Eucalyptus Leaf Disease Complex" is now more appropriate. The overall aim of this thesis was to investigate the Eucalyptus Leaf Disease Complex in Portugal, focusing on species diversity, taxonomy and the role played by each species in the disease complex on Eucalyptus globulus. Literature on the Eucalyptus Leaf Disease Complex was reviewed and the species were distributed into several genera. A survey based on symptomatic leaves collected from several Eucalyptus globulus plantations and characterized by morphological and molecular tools provided an overview of species incidence and of the most frequent species in the disease complex. The present work reveals additional species of Mycosphaerella senso lato associated with eucalypt plantations in Portugal. Thus, five new records of Teratosphaeria and phylogenetically related species were added to the Iberian Peninsula, namely, Neodevriesia hilliana, for the first time on Myrtaceae; Quasiteratosphaeria mexicana, Teratosphaericola pseudoafricana, Teratosphaeria pluritubularis and Teratosphaeria lusitanica, a new species. Furthermore, new anamorphic structures were found and two new combinations were made. Regarding other genera, some species were observed for the first time, such as Cladosporium cladosporioides, Fusicladium eucalypti, Mycosphaerella madeirae, in the mainland. In addition to leave diseases, Teratosphaeria gauchensis was found causing a severe stem and trunk canker on Eucalyptus globulus. The aggressiveness of several species was compared to evaluate each species individually in the complex, permitting to distinguish different behaviours, from primary to secondary pathogens. Cladosporium cladosporioides, M. communis and M. lateralis, appeared to be more aggressive than Teratosphaeria nubilosa. In fact, contrary to the prevailing views on this disease complex, Teratosphaeria nubilosa is not the only species responsible for the disease, which clearly involves a complex of species acting together

Species identification of Mycosphaerella leaf blotch disease (MLD) on Eucalyptus globulus in Portugal

“Mycosphaerella leaf disease” é causada por espécies de Mycosphaerella e vários anamorfos. Em Portugal, esta doença foi largamente ignorada até 1998 quando foram verificados sérios estragos em plantações comerciais de Eucalyptus globulus. O objetivo deste trabalho foi dar uma contribuição ao levantamento inicial de “Mycosphaerella leaf disease", clarificando a composição do complexo Mycosphaerella. É apresentada (Capítulo 1) uma panorâmica da situação mundial e uma lista detalhada das espécies detetadas em Portugal. As espécies foram identificadas com base em métodos moleculares (Capítulo 2) e na sua morfologia (Capítulo 3). Adicionalmente, ao objetivo inicial desta tese, foi estabelecida uma primeira avaliação da suscetibilidade de clones e famílias de eucaliptos em condições experimentais. /ABSTRACT - Mycosphaerella leaf disease is caused by species of Mycosphaerella and several anamorphic form genera that have been associated to Mycosphaerella. ln Portugal, this disease was largely ignored until 1998 when serious damage on commercial plantations of Eucalyptus globulus was reported. The aim of this work was to give a contribution to initial survey of Mycosphaerella leaf disease, clarifying the composition of Mycosphaerella complex. An overview of worldwide situation and a detail list of species reported in Portugal is presented (Chapter 1). Species were identified based on molecular methods (Chapter 2) and on their morphology (Chapter 3). Additionally, of the initial aims of this thesis, a first evaluation of clones and families eucalypts susceptibility in experimental conditions was established