Infectious diseases of horseradish (Cochlearia armoracia L.) in Poland.

Poland is an important horseradish grower in Europe, therefore the problems concerning its cultivation and diseases are considered vital. Horseradish diseases can be classified as non-infectious and fungal, bacterial or virus origin. The most important fungal disease is white-rust caused by Albugo candida, which can be responsible for up to 50% loss of yield, in the case of heavy infection. Bacterial diseases are not very important now. Turnip mosaic virus (TuMV), arabis mosaic virus (AMV) and tomato black ring virus (TBRV) were found so far on horseradish in Poland. The most important is TuMV, which was found in almost 100% collected horseradish samples and caused yield loss about 40%. The virus TuMV belongs to the Potyvirus genus (VC57.0.1) from the Potyviridae family (VC57), which is the largest family of plant viruses. It infects many economically important plants. Attempts to eradicate TuMV by means of thermotherapy proved ineffective. At the Research Institute of Vegetable Crops, methods of obtaining TuMV-free horseradish plants (together with methods of its fast multiplication) have been developed in in vitro cultures.