Characterization of Alternaria Species Associated with Blight Disease of Edible Zucchini (Cucurbita Pepo L.) in India

Zucchini, a valuable crop worldwide, is susceptible to various fungal pathogens, including Alternaria species. This study identified Alternaria alstroemeria as a causal agent of blight disease in zucchini plants in India based upon the morphological and molecular (using ITS (internal transcribed spacer) region as a genetic marker) analysis. Further, the molecular identification revealed the fungal isolate as Alternaria alstroemeria with a query cover of 96% and sequence similarity of 99.60%, having accession no. NR163686.1. The pathogenicity test was also carried out by spraying spores (3 × 10⁵ conidia/mL) collected from the culture of the fungus Alternaria alstroemeria on young zucchini plants, and similar early symptoms of blight were observed on inoculated plants as compared to control plants. The essential oils (EOs) from seeds of clove (Syzygium aromaticum) and dill (Anethum graveolens L.), were found to exhibit antifungal activity against Alternaria alstroemeriae. These findings provide crucial insights for developing effective biocontrol measures to mitigate the impact of this pathogen on zucchini production. In conclusion, the identification of Alternaria alstroemeria on Cucurbita pepo responsible for blight disease suggested that zucchini is also another host for Alternaria alstroemeria.