Abstract

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Vernonia galamensis ssp. galamensis var. ethiopicais a new annual industrial oilseed crop. ‘vernonia oil’ used in the chemical (glue, paint and plastics), pharmaceutical and agro-industrial industries. Powdery mildew caused by Erysiphecichoracearum is major problem of Vernonia production in southern parts of Ethiopia.It causes severe wilting, death of leaves, premature defoliation, and growth reduction andpermanent damage of the crop. It may occur at any time during the growing season; however, it is usually most severe in the late summer months. Therefore, the aim of this study was to evaluate the efficacyof some registered fungicides for the management of powdery mildew on Vernonia. The experiment was laid out in randomized complete block design (RCBD) with three replications. A plot size of 3m × 3m with 50cm × 50cm spacing between plants was used. Fungicides cymoxinil + copper oxychloride, Propiconazole, Mancozeb, Spiroxamine 500gm/lt and Thiophanate Methyl were applied at recommended rate as treatments and untreated control.Data on disease incidence, severity, disease control, seed yield and oil yield were recorded.Foliarapplications of treatments were made 2015 and 2016.Among treatments, the degree of powdery mildew control ranged from 66.33 to zero (untreated control); however, all treatments significantly reduced disease severity compared to untreated plants. Among all products tested for the control of powdery mildew; Cymoxinil + Copper oxychloride and //.Thiophanate Methyl were higher than the rest of chemicals tested.Highest significant disease severity (p≤0.05) was also achieved with these fungicides which reduced the disease severity to 8.8 and 9.13% respectively as compared to 24% in control. Therefore, Cymoxinil + Copper oxychloride and Thiophanate Methyl were more effective for management of powdery mildew in field conditions.

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