The inhibitory effect of some plant crude extracts against Podosphaera xanthii the causal agent of cucumber powdery mildew

Ghasemi,; Zare,; Bahraminejad,; Abbasi,

	The inhibitory effect of some plant crude extracts against Podosphaera xanthii the causal agent of cucumber powdery mildew
Euphrates Journal of Agriculture Science
Article 1, Volume 3, Issue 0, 2011, Pages 152-155
Authors
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Abstract
Abstract : Powdery mildew caused by Podosphaera xanthii and Golovinomyces cichoracearum, is one of the most destructive foliar diseases of cucumber. It has been found that P.xanthii is the main agent of this disease in Iran. Application of fungicide is the most effective method for the disease control. However, regarding the problems created by synthetic pesticides application, environmentally safe methods are needed to replace chemical pesticides or reduce their consumption in the ecosystem. Therefore, in this study, the antifungal activity of plant natural extracts was investigated against P.xanthii. The crude extract of 15 plants was obtained using methanol as a solvent. The extract (50 mg/ml) was sprayed on cucumber seedlings at the second true leaf stage. Twenty-four hours after spraying, the seedlings were inoculated with a conidial suspension at concentration of 5×104 spore/ml. The experiment was conducted as a completely randomized design, with four replicates. Twelve days after inoculation, the severity of powdery mildew was evaluated based on number of spores produced over the first true leaves of each plant. The results of the experiment showed that seven out of 15 plants were effectively reduced the severity of the disease. The most active plant extracts against P.xanthii were Synzygium aromaticum, Carum copticum and Hypericum perforatum with 99, 98, 97 % inhibition, respectively.Key Words: Powdery mildew, plant extract, Synzygium aromaticum, Carum copticum

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