Antifungal activity of plant extracts against Diplocarpon rosae causing black spot of rose

Abstract

Rose (Rosa spp), one of the most commercially valued flower crops, is extensively cultivated all around the world. Black spot caused by Diplocarpon rosae Wolf. is a most devastating and widespread disease in rose plants. Due to its severe infection during rainy conditions repetitive application of chemical fungicides becomes necessary for its control. Frequent application of synthetic fungicides leads to deteriorated quality and fragrance of flowers and hence its market value gets reduced. To overcome this problem, a study have been conducted to evaluate the antifungal activity of plant extracts against Rose black spot disease causing pathogen Diplocarpon rosae. Aqueous extracts of Coleus forskohlii, Lantana camera, Leucas martinicensis, Withania somnifera, Sargassum muticum, Ulva lactuca, Zingiber officinale, Allium sativum and neem oil were screened against the pathogen by poisoned food technique at 10 and 20 per cent concentration. The result revealed that three plant extracts - Allium sativum, Leucas martinicensis and Zingiber officinale showed significant antifungal activity against D.rosae. According to the obtained result, these plant extracts can be used as biological fungicide against rose black spot disease at field.