Formation of microsclerotia of Verticillium dahliae on various crops

In 2 pot experiments, potato (cultivars Element, Mirka, Ostara and Astarte), pea, sugarbeet, onion, flax, spring barley, faba beans, spring wheat and spring rape were inoculated with V. dahliae by root dipping or by growing the plants in artificially infested soil. In both treatments the dry matter yield and formation of microsclerotia were determined for aerial parts. In plants grown in infested soil, the DW and microsclerotia formation were determined in stubbles and roots as well. The highest numbers of microsclerotia per g plant material and per pot in the root dipping treatment were found on potato, flax and barley. The microsclerotia density on potato cv. Element, pea and barley was higher in the root dipping treatment than in the soil infestation treatment. The reverse was true for potato cultivars Ostara and Mirka. Dry matter yield of the harvestable organs of potato cultivars Element and Astarte, flax, sugarbeet and barley was lower in the root dipping treatment than in the soil infestation treatment. The greatest inter-crop differences in the microsclerotia yield/pot were in the aerial parts. Flax gave the highest numbers of microsclerotia/pot, followed by the 4 potato cultivars. The other crops had a much lower microsclerotia yield. It is suggested that the results will be useful for modelling effects of various crops on the soil population at crop and farm level