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

Background: The leaf spot of cabbage caused by pathogenic fungi, Alternaria brassicicola, tends to cause serious diseases in crucifers with 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, and hence, an alternative eco-friendly approach of plant disease management by means of plant extract is ‘the need of the hour’. Materials and Methods: Pathogen was isolated from diseased plant part by tissue segmentation followed by screening and maintenance. 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, Oscimum 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 per cent concentration, 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 aqueous extract of A. indica showed highest inhibition (upto 97.2%) at 10 and 15% concentration among all the other plant extracts.