Alternaria sp. AS A CAUSAL AGENT OF LEAF SPOT AND PLANT WILT OF GERANIUM IN THE TERRITORY OF THE CITY OF KRUŠEVAC

Abstract

Geranium (Pelargonium spp.) is an important ornamental plant susceptible to diseases caused by phytopathogenic fungi, among which Alternaria sp. stands out as the causal agent of brown necrotic leaf spots with concentric zones. Symptomatic samples were collected in March 2025 in the vicinity of Kruševac, and five isolates (MA1–MA5) were selected for further investigation.Pathogenicity was confirmed using the stem wounding method, and inoculated plants developed typical symptoms, including drying and plant death. Morphological and cultural characteristics were examined on PDA, CMA, and WA media; the average conidial size was 29.45 × 13.16 μm, and the highest mycelial growth was recorded on CMA. PCR analysis (ITS1/ITS4 and EF1-728F/EF-2) confirmed the presence of fragments of the expected size (~500 bp) in all isolates. The results confirm the presence of A. alternata on geranium in Serbia and emphasize the importance of timely identification for disease management