In vivo anti-mildew activity of essential oils against downy mildew of sunflower caused by PLASMOPARA HALSTEDII

Abstract

Commercial essential oils (EO) obtained from different parts of black cumin (N. sativa), mustard (S. nigra), St. John's wort (H. perforatum), garlic (A. sativum), grape (V. vinifera), and ginger (Z. officinale) plants were evaluated for in vivo anti-mildew activity against pathotypes '771' and '773' of P.halstedii. The EOs were examined at concentrations of 0.2%, 0.4%, and 0.6% in susceptible sunflower variety '08-TR-003' as seed, foliar, and seed + foliar treatments.It was concluded that seed treatments could be applicable and appropriate, due to the phytotoxic effects of foliar treatments at increasing concentrations. Moreover, it was observed that seed treatments with St. John's wort, mustard, grape, ginger, or garlic EOs at a concentration of 0.6% exhibited anti-mildew activity with a decrease in sporangium quantity above 80% for pathotypes '771' and '773'. Seed treatment with grape EO had the highest anti-mildew activity at a concentration of 0.6% and was found to be the most effective with a decrease in sporangium quantity above 90% for both pathotypes of the pathogen.