Abstract
Verticillium chlamydosporium, Paecilomyces lilacinus, Aspergillus flavus, Arachniotus sp .. Bacillus subtilis and Pseudomonas aeruginosa were evaluated against actively multiplying culture (107 cfu/ml) of Xanthomonas campestris pv. maivacearum isolated from bacterial blight affected cotton leaves. Data recorded after 12, 2~. 36 and 48 hr revealed that all the fungal antagonists significantly retarded the multiplication of the pathogenic bacterium. I erttcillium chlamydosporium and Paecilomyces lilacinus were found effective by producing 3.23 and 3.23 cm inhibition zones followed by Aspergillus flavus (2.53 cm), Arachniotus sp. (1.87 cm), Bacillus subtilis (0.22 cm) and Pseudomonas aeruginosa (0.15 cm) in that order. Fungal antagonists were more effective than bacterial antagonists. Spray of culture filtrates of the most effective antagonistic fungi on four commercially grown cotton varieties significantly reduced leaf shedding and number of bare nodes and increased number of boils, boil weight, number of healthy leaves and ultimately yield of cotton plant as compared to untreated control. Key words: antagonistic organisms, bacterial blight, Xanthomonas campestris pv. malvacearum
