Phenotypic diversity in phytopathogenic Dickeya zeae associated with rice and maize in Punjab

Dickeya zeae is known to cause soft rot diseases in a wide range of crops. Under Punjab condition this pathogen is known to cause stalk rot of maize and is now emerging as a pathogen of rice causing bacterial foot rot. During the surveys conducted in this study, bacterial stalk rot of maize was found to be invariably present in all the districts with maximum incidence in SBS Nagar during 2018 (12.7%) followed by Jalandhar (12.0%) and Gurdaspur (6.5%) during 2017. Disease severity was highest in Jalandhar (10.0%) during 2017. The incidence of bacterial foot rot of rice was highest in Gurdaspur (7.3 and 6.2% during 2018 and 2017, respectively) followed by Patiala (5.8%) during 2018.The disease severity was also highest in Gurdaspur (5.7 and 4.9% during 2018 and 2017, respectively) followed by Patiala (4.1%) during 2018. The pathogen was isolated from different locations and a total of forty isolates were obtained. These isolates were differentiated on the basis of a set of biochemical tests. The numerical analysis of these tests revealed six major groups of the isolates associated at 60 per cent similarity coefficient. Isolates were also subjected to antibiotic resistance test and most of the isolates (82.5%) were found to be sensitive to neomycin and all were resistant to ampicillin.