Efficacy of Fungicides and Botanical Extracts against Alternaria brassicicola Causing Leaf Spot of Cabbage (Brassica oleracea var capitata L.)

Abstract

Background: The leaf spot of cabbage caused by the pathogenic fungus Alternaria brassicicola tends to cause serious diseases in crucifers, resulting in considerable economic losses in their yield and storage. Application of chemical fungicides in high doses can have an adverse effect both on the host and the environment; hence, an alternative eco-friendly approach to plant disease management by means of plant extracts is ‘the need of the hour.’ Materials and Methods: The pathogen was isolated from the diseased plant part by tissue segmentation, followed by screening and maintenance. The in vitro poisoned food technique was followed to study the comparative effectiveness of commercial fungicides and aqueous botanical extracts of Azadirachta indica, Ricinus communis, Aloe vera, Ocimum sanctum, and Cassia alata, against A. brassicicola.Results: Hexaconazole showed complete inhibition of mycelial growth of the pathogen at 0.1, 0.15, and 0.2 percent concentrations, whereas the least mycelial inhibition was observed in 0.2% of Ridomil (67.1%). In vitro assays for botanical extracts against mycelial growth of A. brassicicola revealed that the aqueous extract of A. indica showed the highest inhibition (up to 97.2%) at 10 and 15% concentrations among all the other plant extracts.

Keywords: Alternaria brassicicola; Botanical extracts; Fungicides; Poisoned food technique