Control of common bunt (Tilleta tritici and T. laevis) of wheat (Triticum aestivum cv. ‘Laura’) by fumigation with acetic acid vapour

Abstract

Common bunt caused by Tilletia tritici and T. laevis remains an important disease of wheat, particularly in organic production where effective fungicides are not available. Acetic acid (AA), a potential organic seed fumigant, was evaluated for control of common bunt of wheat. The highly susceptible spring wheat cultivar Laura was inoculated with bunt spores and then fumigated with 2 and 4 g kg-1 AA vapour in 23 L chambers for 1 h at 20°C. Fumigation reduced field infection levels of common bunt in trials conducted at Lethbridge, AB during 2000, 2001, and 2003. The 4 g kg-1 rate was more effective than the 2 g kg-1 rate in reducing bunt infection, although both rates were as effective as Vitavax, the standard seed-treatment fungicide treatment. Some reduction in tiller numbers was associated with the AA treatments especially at the 4 g kg-1 rate. In vitro tests on artificial growth media showed that AA significantly decreased seed-borne mold contamination caused by several species of fungi. Acetic acid fumigation could be an important organic alternative to fungicides for control of common bunt. Key words: Covered smut, organic, seed treatment, stinking smut, vinegar