Testing clubroot-resistance of turnips in the netherlands and the physiologic specialization of plasmodiophora brassicae

摘要: 1. Clubroot is the main disease of fodder turnips in Netherlands. Growing resistant varieties only practical means control. 2. Sowing seeds first half July more efficient for selection clubroot resistance than sowing normal period, early August. 3. Artificial infestation a field soil may have advantages over naturally infested selecting resistance. “Furrow infestation” i.e. putting from heavily diseased farm fields into furrows before turnips, seems practicable method. 4. Ten strains Plasmodiophora brassicae were distinguished Netherlands and Belgium on basis infection spectrum large set differential hosts. Seven them originate where are frequently grown. Each strain represents group isolates with similar spectra. 5. Turnip included 39 th Dutch Descriptive List Varieties Field Crops (1964) can be divided three groups based their reaction to strains: 1) V-group, comprising which very susceptible nearly all fields, 2) M-group, fairly most 3) E-group, Netherlands; however, they just as V-and M-group number Belgium. In addition fourth distinguished, viz. L-group, some not mentioned “List”. These moderately Netherlands. 6. Races fungus aggressive apparently been prevalent certain many years. other these races gradually increase during years when A mixture different likely occur every field. above also has regarded races. 7. Turnip found abroad usually turn out Only Belgian proved our country. few countries. Clubroot occurring turnip foreign countries, therefore, generally appear those