Prevalence of Fluorescent Pseudomonads in Cruciferous Rhizosphere, Their Characterization and Severity of Black Rot of Cabbage in Northern Karnataka

Abstract

Cabbage (Brassica oleraceae var.capitata (L.)) is one of the most important vegetable crop and cultivated extensively in tropical and temperate regions of the world. Cabbage infected by many diseases among those, black rot of cabbage caused by Xanthomonas campesrtis pv. campestris is one of the most yield limiting and destructive pathogens of cruciferous crops worldwide. A random survey conducted during Kharif 2015 in cabbage growing areas of northern Karnataka revealed that incidence of black rot of cabbage was observed in all district surveyed. The maximum disease index of 23.36% was noticed in Belagavi district, followed by Dharwad (20.17%) and the least disease index was observed in Haveri (18.65%). The severity of black rot was highest at heading stage compared to vegetative stage. Prevalence of fluorescent pseudomonads was observed in all districts surveyed and wherever fluorescent pseudomonads were present in those locations the disease occurrence and severity was less compared to location where pseudomonads were they were absent. Eight fluorescent pseudomonads such as GRG- FP, HGK- FP, LKR- FP, KKL- FP, KBG- FP, KBG- FP, SKP- FP, MKH- FP and ARB- FP were identified based on their morphological characters, physiological and biochemical tests.