Caracterização e epidemiologia comparativa de espécies de Colletotrichum em anonáceas no estado de Alagoas

Abstract

Anthracnose is an important disease of Annonaceae. Caused by species of the genus Colletotrichum, is one of the limiting factors of production due to severe attack on leaves, fruits, flowers and petiole. In Brazil, Colletotrichum gloeosporioides was reported as etiologic agent associated with anthracnose in Annonaceae. The objectives of this study were to identify by molecular characterization and Morphocultural species of Colletotrichum in Annonaceae, to evaluate the influence of temperature on disease intensity, and the effect of fungicides and salicihidroxâmico acid on the mycelial growth of these species. Colletotrichum isolates, obtained from leaves showing typical disease symptoms, were collected in Maceio, Palmeira dos Indios, Arapiraca, Igaci, Delmiro Gouveia, Estrela de Alagoas and Maragogi municipalities. Molecular characterization was carried out with ninety isolates which glyceraldehyde 3-phosphate dehydrogenase gene (GAPDH) was sequenced and analyzed as an initial measure genetic diversity. Thirty isolates were selected to represent genetic diversity rangeand geographical originby sequencing chitin syntase (CHS-1) and β-tubulin (TUB2) genes and rDNA-ITS region. Cultural characterization was performed by mensuration mycelial growth at 25 °C and colonies aspects. Morphological characterization was performed through measurements of conidia and apressoria. Analysis of multilocus sequence, together with morfoculturais characteristics was possible to prove that at least five Colletotrichum species are responsible for causing anthracnose in cone and soursop in Alagoas state: C. karstii, C. tropicale, C. siamense, C. theobromicola and C. fructicola. Colletotrichum species showed greater lesion size at 25 °C. Colletotrichum tropicale was the species that obtained a higher mycelial growth at 10mg ml¹ concentration compared with other species. The difenoconazole and thiophanate methylfungicides showed the best in vitro control of Colletotrichum species, however, all species showed reduced growth in the presence of fungicides independent of their ingredient active. The fungicide azoxystrobin in presence of ácido salicihidroxâmico inhibited the mycelial growth of Colletotrichum species.