Effect of treating seeds infected with an aqueous agave extract in order to control common bunt in wheat and loose smut in barley

Summary

Aqueous extract from the sisal agave, A. sisalana, is known to contain antifungal activity. In two small field experiments we have tested the effect of seed treatment using A. sisalana extract in order to control common bunt, Tilletia caries, in winter wheat and loose smut, Ustilago nuda, in spring barley, respectively. Disease incidence of plants from treated seeds was compared to incidences in plants from non-treated seeds and seeds treated with pure water. In comparison to controls, a reduction of disease incidence of T. caries by 75% was observed in winter wheat and a reduction of U. nuda incidence by 20% was observed in spring barley following seed treatment with A. sisalana extract. The observed difference in efficiency towards these two pathogens is likely to reflect that spores of T. caries are located on the seed surface and there by immediately exposed to this type of antifungal seed treatment whereas the seed-borne stage of U. nuda is located in or near the embryo of the seed, and thereby better protected against antifungal molecules applied from the outside to the seed.