Fifteen years of organic cereal seed health analyses at Agroscope ART

Investigations on organically produced cereal seed over the past 15 years have shown the importance of the control of seed-borne diseases. Although disease pressure depends on annual fluctuations caused by the weather, infestation with common and dwarf bunt (Tilletia caries/T. controversa) has increased in the last few years, with the former primarily occurring on spelt and the latter on wheat. On spelt, the cultivar «Oberkulmer Rotkorn» seems to be particularly susceptible to common bunt. Since the disease can spread very quickly through contaminated seed, it is important to use non-infested starter seed. In winters with abundant snow fall and persistent snow cover (2008/2009), dwarf bunt also occurred in lower altitudes. Problems with snow mould occurred primarily on rye, with over half of the examined seed samples frequently exceeding the threshold value. Effective seed dressings registered for organic farming are only available against common bunt on wheat and spelt; they are only partially or insufficiently effective against snow mould (Microdochium nivale/M. majus) and dwarf bunt.