Cladosporium cladosporoides, pathogen of sunflower seed

Abstract

The sunflower (Helianthus annuus L.) is one of the most important oil crops in the world and the most important cultivated oil crop in Serbia, where it is grown on about 160,000 to 210,000 ha and the seed yield ranging from 1.7 to 2.3 t/ha. Several seed-borne fungi including species of Alternaria, Aspergillus, Cladosporium, Drechslera, Epicoccum, Fusarium and Penicillium, have been reported from sunflower seeds and could cause different levels of losses in its production. During the routine seed quality control and seed health testing analysis of sunflower, according to ISTA Rules, Cladosporium spp. infection was observed on an average of 5%. The aim of this study was the isolation and identification of Cladosporium spp. based on their morphological characteristics and molecular analyses. Isolation of the pathogen was carried out by transferring infected seeds onto a potato dextrose agar (PDA), and incubated for 5 days at 25 °C. Cladosporium-like colonies were transferred onto fresh PDA and water agar (WA, 17 g agar and 1 liter of distilled H2O) to obtain monosporial isolates. Seven days later, five isolates formed grey-greyish brown, velvet-like colony with apically and laterally branched conidiophores. Margin of the colony was white to grey-olivaceous. Conidias were mostly globose to subglobose, 3-4.5 µm in diameter, mild to dark olivaceous brown.