THE ALTERNARIA leaf spot fungus cause a serious problem for …….anise (Pimpenella anisum) cultivation in Egypt. The aim of this study was to examine the possibility of using some essential oils as alternatives to synthetic fungicides inhibiting Alternaria radicina growth. The effect of those essential oils (EOs) on growth and productivity of anise was also investigated in two successive seasons of 2010/2011& 2011/2012. In vitro experiments were carried out using six essential oils of thyme, caraway, clove, mint, rosemary and lemongrass with three concentrations of 1, 5 and 10 μl ml-1. Complete inhibition of growth of the pathogen was obtained by lemongrass oil at 5μl ml-1 .Oils of thyme and caraway were inhibitory at relatively higher concentrations (10μl ml-1). Oils of lemongrass, caraway and thyme, gave pronounced protection of anise plants against invasion of leaf spot pathogen. The maximum reduction of disease incidence (DI) and severity (DS) of leaf spot along the growth period in both growing seasons was observed by lemongrass at both concentrations (5 and 10 μl ml-1), and by caraway and thymes oils at 10 μl ml-1 concentrations.
Vegetative growth of anise
i.e. plant height, number of branches and number of leaves/plant and yield components i.e. fruits and essential oil yield were responded positively to different essential oils application. Significant increases in the photosynthetic pigments of anise leaves were determined as a result of different essential oils application. Lemongrass essential oil at 10 μl ml-1 increased seed yield per plant with 77.38 % over control plants followed by, thyme oil at 10 μl ml-1 reordering 66.85 % increment (average of two seasons) while, caraway oil at 10 μl ml-1 ranked thirdly. The maximum reduction of disease incidence and severity of leaf spot along the growth period was observed by lemongrass at both concentrations (5 and 10 μl ml-1) followed by caraway and thymes oils.
This study has demonstrated that the EOs are promising antifungal agents, which could be used widely as natural fungicides in the protection of anise against
Alternaria radicina and improving plant growth and productivity.