Efficacy of Plant Oils against Xanthomonas axonopodis pv. punicae

Pomegranate is an important tropical fruit crop, and the juice from the pomegranate is one of the most powerful antioxidants. Since 2002, pomegranate is severely affected by bacterial blight disease caused by Xanthomonas axonopodis pv. punicae. The occurrence of bacterial blight disease was noticed in all the pomegranate growing areas of Tamil Nadu. A bacterial pathogen was isolated from the infected plant parts and identified as Xanthomonas axonopodis pv. punicae through cultural and biochemical characterisation. With the aim of developing eco-friendly management of bacterial blight of pomegranate, different plant oils such as neem, mahua, thyme, clove, eucalyptus, lemongrass, pungam, peppermint, wintergreen, citronella were screened. Among these plant oils, thyme oil (10 per cent) recorded maximum inhibition (1.9 cm) of Xanthomonas axonopodis pv. punicae followed by lemon grass oil (1.85 cm). The Eucalyptus oil recorded an inhibition zone of 1.6 cm. No inhibition zone was observed in neem oil, pungam oil, mahua oil and winter green oil. Among these plant oils, thyme oil and lemon grass oil effectively retarded the growth of pomegranate bacterial blight under in vitro condition.