Eco-friendly Management of Alternaria Leaf Spot of Brinjal: A Review of Botanical Strategies

Abstract

Brinjal (Solanum melongena L.) is an important vegetable crop extensively cultivated in tropical and subtropical regions, where it holds considerable nutritional and economic value. Despite its wide adaptability and importance, brinjal productivity is significantly constrained by several diseases, among which Alternaria leaf spot, caused by Alternaria alternata (Fr.) Keissler, is particularly destructive. The disease affects foliage and reduces photosynthetic efficiency, ultimately leading to substantial yield reductions that may range from 20 to 80% under favourable environmental conditions. This review synthesises current knowledge on the role of botanicals in managing Alternaria leaf spot of brinjal, highlighting their potential as eco-friendly disease control agents. Conventional management relies heavily on synthetic fungicides, which pose challenges such as high cost, environmental hazards, residual toxicity, and pathogen resistance. In recent years, botanicals have emerged as sustainable alternatives due to their eco-friendly nature, biodegradability, and diverse antifungal properties. Plant-derived extracts rich in secondary metabolites—such as flavonoids, alkaloids, phenolics, and essential oils—exhibit inhibitory effects on fungal growth and pathogenicity. Several botanicals, including neem, garlic, tulsi, and clove, have demonstrated promising efficacy both in vitro and in vivo against Alternaria spp. Their mechanisms of action involve disruption of fungal cell membranes, inhibition of enzymes, and suppression of toxin production. Greater emphasis is being placed on sustainable crop protection approaches that incorporate botanical extracts into integrated disease management programmes. The adoption of such strategies can reduce dependence on synthetic fungicides, minimise environmental risks, and promote safer and more sustainable agricultural production systems. Overall, the use of botanicals represents a viable and environmentally sound approach for the management of Alternaria leaf spot in brinjal.