Screening of winter barley varieties (Hordeum vulgare) for resistance against loose smut (Ustilago nuda) and covered smut (Ustilago hordei) in Germany

Summary

Up to now organic farmers depend greatly on conventionally bred and produced varieties of barley. A turning point was set in 2004 by EU regulation No. 1452/2003 restricting the use of conventionally propagated seed and planting material for organic agriculture. Concerning smut fungi in barley, conventional seed producer's attention was rarely directed to plant resistance due to the possibility of chemical seed treatment (controlling the diseases completely). A main problem for organic seed producers is that organically produced seeds have to fulfil the same regular phytosanitary requirements like conventionally produced seeds. For the production of certified seeds not more than five ears infected with Ustilago hordei (Uh) and/or U. nuda (Un) are allowed on an area of 150 m² in Germany (RUTZ 1998). Though warm or hot water treatment can give excellent control of Un and Uh in organic farming (WINTER et al. 1996), the effect is not sufficient for seed production. Even biological control agents (for example Tillecur®) cannot reach the demands of the guidelines reliably. As an effective way to keep the restrictions remains the cultivation of resistant varieties. Aim of the presented study was to screen winter barley varieties for their degree of smut resistance in Germany. It started in 2000 (KLAUSE & SPIESS 2003) and is sponsored within the Federal Organic Farming Scheme since 2002.