Characterization of fungi of the genus Stemphylium associated to pome fruits in Portugal

Mestrado em Engenharia Agronómica - Instituto Superior de AgronomiaBrown spot of pear, associated to Pleospora allii/Stemphylium vesicarium, is economically important in pear production in Europe and was detected, in 1996, in Portugal. The causal agent is known to share similar morphological characteristics with other fungi in the genus, namely S. botryosum known as a storage fungus, making the identification between them quite difficult. With the aim to contribute for a better knowledge of brown spot in pears, the pathogens involved in this disease and its presence in other fruit trees, we studied, from 30 Stemphylium monosporics isolates obtained from apples and pear fruits, and pears leaves, from Portugal, the optimal grow temperature, cultural, morphologic and biometric characteristics from anamorphs and/or teleomorphs, the time required for ascospore prodution and phylogenetic relationships, inferred from ITS and gpd sequence data. The optimum growth temperature stood between 22.5º C and 27.5º C, the ratio between length and width ranged from 1.38 to 2.38. The number of days until mature ascospores were produced ranged between 10 and 54 days. The gpd fragments of 28 isolates clustered with S. vesicarium from NCBI bank and the whole data allowed to identify 29 isolates as S. vesicariu