Effect of seed treatments with EM (Effective Microorganisms) in control of common bunt (Tilletia tritici) in wheat

Common bunt is one of the most important diseases in winter wheat, and one of the most intensively pesticide treated diseases in regions, where this pathogen occurs. When pesticides are not used in seed propagation, i.e. in organic agriculture, this disease is normally a serious problem. EM1 (Effective Microorganisms) is a product used in Kyusei Nature Farming, containing a bunch of different microorganisms against various fungal plant diseases. In order to develop methods to diminish pesticide use, and to improve organic agriculture, the potential of EM to regulate this pathogen was investigated. In 1996 seeds contaminated with teleutospores of Tilletia tritici were treated with two levels of EM1, two levels of acetic acid and two levels of milk powder. A combination of EM1 and milk powder were tested as well. EM1 had a significant effect on disease rate (87.6% reduction) when applied in high dosages (150ml/kg seed), but in this dose germination vigour and field emergence were also negatively affected. The use of the same dose of autoclaved EM1 had almost the same effect on disease rate and germination vigour. This might indicate, that the causative agent in the EM1 product are not the effective microorganisms themselfs, but the metabolites of the organisms, most probably lactic acid. Using acetic acid (1.22M, 30ml/kg) it was possible to get a better control of the pathogen with no significant harm to germination. Based on these trials it can be concluded, that EM1 is not an optimal control agent against common bunt. However the use of EM1 did reduce the disease rate, and this can therefore be a positive side-effect if EM1 is used as a seed treatment for other reasons