Efficacy of Some Fungicides, Commercial Plant Oils and Bio-Agents against Drechslera Graminea Inciting Barley Leaf Stripe Disease

Abstract

The antifungal activity of 5 fungicides, 3 commercial plant oils and 2 bio-agents were tested in vitro and in vivo against Drechslera graminea (Rabenh. ex. Schlech) Shoemaker (telemorph: Pyrenophora graminea Ito and Kuribayashi, the causal organism of leaf stripe disease on barley (Hordeum vulgare L.). Among fungicides tested, Opus at 1µl/L and Switch at 1mg/L concentration and Bellis at 2mg/L showed 100% mycelia growth inhibition of D. graminea. The results of commercial plant oils tested in vitro revealed that the coriander showed highest inhibition of mycelial growth at 15%. The dual culture technique revealed that fungal bio-agent (Trichoderma harzianum) was better than bacterial bio-agent (Bacillus subtilis) in inhibiting the growth of D. graminea. Greenhouse and field experiments were carried out to evaluate the efficacy of all tested treatments on disease incidence, yield components, enzymes activity and phenolic compounds. The tested fungicides, plant oils and bioagents applied as seed dressing showed an effectiveness to large extent for controlling leaf stripe disease expressed as a reduction in disease incidence and increased yield components in comparing with the untreated plants. As well as, the all treatments caused an increment in activities of peroxidaxe, polyphenol oxidase and chitinase enzymes and increasing in phenolic compounds compared to control treatment. Although the five tested fungicides were more effective in reducing the linear growth of the pathogen (D. graminea) in vitro and suppressing the disease in vivo than the plant oils and bio-agents, they are considered environmentally safe and can be used as alternative substances in disease management.