CARACTERIZAÇÃO MORFOLÓGICA E MOLECULAR, SINTOMATOLOGIA E SEVERIDADE DE Pestalotiopsis spp. STEYAERT EM MUDAS DE Eucalyptus dunnii MAIDEN

Abstract

The versatility of uses in adaptation to the sites by the different species of cultivated eucalyptus have propelled the research aiming, mainly, the resistance to pests and diseases. Even though Eucalyptus dunnii is one of the most used species in south of Brazil, issues such as phytosanitary problems in this species have been neglected. Among the main causes of diseases in this crop, Pestalotiopsis spp. has deserved attention, precisely because it is a pathogen that needs an entry point, finding, therefore, some ideal conditions to make the penetration, due to climatic phenomena, typical of this region as frost and hail. Therefore, the main objective of this study was: to characterize morphologically and molecularly isolated from Pestalotiopsis spp. PB and PE to quantify the severity of Pestalotiopsis spp. on stem and leaves of Eucalyptus dunnii. The phytopathogen in question was isolated from three different cultures, PB (obtained from Mimosa flocculosa canker) and PE (obtained from leaf spot in Eucalyptus grandis) belonging to microbial collection of the Forest Protection Laboratory of UNICENTRO-Irati and isolates P2 and P5 (obtained from Carya illinoinensis) belonging to microbial collection of the Elocy Minussi Phytopathology Laboratory of the Federal University of Santa Maria-RS. For better understanding, this work was divided in three chapters: 1) Morphological and molecular characterization of the isolates PB and PE; 2) To describe the leaf symptoms and to quantify the severity of the different isolates in this organ; 3) To describe the symptoms and quantify stem severity. The molecular sequences of the isolates PB and PE were identical to each other and correspond to the species P. kenyana and P.oryzae. All isolates showed to be pathogenic in E. dunnii, even from different hosts. The PE and P5 isolates showed the highest mean of severity in leaf, with 13.74% and 15.32%, respectively. In relation to the stem, in experiment 1, inoculating only PB and PE isolates, in four different assays, PB presented the highest mean of canker in all assays reaching 43.40 cm2 luating the four isolates, conducted in two tests, P5 presented the highest means in the two assays, 62.41 and 42.81 cm2, respectively. Regarding stem severity, in experiment 1, PB and PE isolates were assessed in four experiments, PE presented 62.99% and in experiment 2, all isolates were evaluated. In two experiments, P5 obtained a mean of 15, 29% in assay 1 and 28.9% in lesion area in assay 2.