In vitro evaluation of botanicals against ralstonia solanacearum causing bacterial wilt of potato

Abstract

Bacterial wilt or brown rot of potato, caused by Ralstonia solanacearum, is a limiting factor of potato production worldwide. The management of the disease is difficult, and the chemicals are least effective and hazardous. Hence, it is needs to develop alternative methods to control this deadly disease, which is effective and eco-friendly. Aqueous and ethanolic extracts of eleven plants were evaluated for the antibacterial activity against Ralstonia solanacearum in in-vitro by well diffusion method. Out of the eleven crude aqueous extracts tested, maximum inhibition zone was observed in bulb extract of Allium sativum (30.21mm) followed by Psidium guajava (25.11mm), Curcuma longa (17.77mm), Tagetes erecta (16.21mm), Carica papaya (14.55mm) and Azadirachta indica (13.77mm). Whereas on evaluation of eleven crude ethanolic extracts, maximum inhibition zone was observed in bulb extract of Allium sativum (29.77mm) followed by Psidium guajava (22.88mm), Tagetes erecta (19.77mm), Carica papaya (15.11mm), Azadirachta indica (14.88mm), Ocimum gratissimum (14.10) and Curcuma longa (11.33mm). After screening, four aqueous extracts of botanicals (Allium sativum, Psidium guajava, Curcuma longa and Tagetes erecta) and four ethanol extracts of botanicals (Allium sativum, Psidium guajava, Tagetes erecta and Carica papaya) which showed inhibition zone ≥15mm were evaluated against R. solanacearum at 1%, 5%, 10% and 15% concentration. Among them, garlic showed superiority over all the plants extracts at all the levels of concentration.