Control of seed-borne snow mould (Gerlachia nivalis) of winter wheat with warm water

Warm water treatment of seeds of winter wheat cv. Runal under practical conditions was compared with a laboratory warm water treatment, a chemical seed dressing, and an untreated control in field and laboratory experiments in 1997-1998. The treatment under practical conditions was performed as follows: seed lots (350 kg) were dipped into water (45°C) for 2 hours in a bin for cheese production, then air-dried (40°C) during.4 hours. For the laboratory treatment, seeds were dipped into water (45°C) in a water bath, then dried at 350C during 5 hours. For the chemical seed dressing, Beret 050 FS (4,8 % fenpiclonil) was applied with a Hege spraying seed dressing machine. The seeds were naturally infected by Gerlachia nivalis (18 % infestation).<br>The practical worm water treatment significantly reduced G. nivalis seed infection from 18 to 1 %. Seed germination was increased by 10 % compared to untreated seeds. In the field experiments, carried out in various regions of Switzerland, the practical warm water treatment significantly increased the numbers of plants/ m2 as well by 73 % compared to the untreated control. Similar results were obtained with the laboratory warm water treatment and the chemical seed dressing.<br>Preliminary results from a dry storage of warm water treated and untreated seeds of the spring wheat cv. Lona during one year at 1O°C showed no difference in control of G. nivalis in the field and in seed germination when compared to unstored seeds. More data should be obtained on the effect of various storage conditions on winter wheat seeds.<br>It is concluded that warm water treatment of winter wheat seeds is an alternative to chemical seed dressing against G. nivailis for organic farming.