Abstract
A new disease has arisen in field grown Chinese cabbage (Brassica campestris ssp. pekinensis) in Denmark. The soil-borne causal agent was shown to be Pythium tracheiphilum Matta, a little known pathogen of lettuce. Until now, outbreaks of the disease in Chinese cabbage were generally attributed to Phytophthora porri Foister, since symptoms of the disease in the field resemble those caused by Ph. porri in Chinese cabbage in cold stores. In some severely affected crops harvest losses in 1994, directly attributable to P. tracheiphilum, were estimated to about 50%, corresponding to a market value of up to $ US 20000 per ha. Outbreaks of the disease coincide with the heading of the crop, while juvenile plants or seedlings are apparently not attacked. It appears that the outer leaves are infected directly from the soil. Mainly above ground parts are affected and colonized by the pathogen, and indications of infection via the root system have not been observed. This is the first record of P. tracheiphilum as a pathogen of Chinese cabbage.
Published Version
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