Isolates of Phytophthora cryptogea Pathogenic to Wheat and Some Other Crop Plants

Abstract A fungus of the genus Phytophthora , frequently isolated from diseased spinach roots and also from field-grown wheat plants in an area in the south of Sweden, was identified as P. cryptogea on the basis of morphology, growth characters and cardinal temperatures. Mycelium or zoospores applied as inoculum in a series of pathogenicity tests induced symptoms in spinach, sugarbeet, wheat, cucumber, oil-seed rape, pea and oats. These ranged from death of all (spinach) or some inoculated plants (sugarbeet and wheat), to only slight root symptoms (oats). Successful re-isolations from all plants tested, confirmed infectivity in all cases. This is the first report of the occurrence of P. cryptogea in Sweden and, as far as we know, of pathogenicity of this fungus to wheat, oil-seed rape and oats.