Interaction of three lucerne cultivars and eleven English isolates of stem nematode (Ditylenchus dipsaci), 'lucerne race'

In pots, 11 English isolates of lucerne race of stem nematode induced hypertrophy in the shoot apices of young lucerne seedlings of the cultivars Europe, Sverre and Vertus. All but one isolate multiplied freely in the shoots of susceptible Europe plants and all isolates multiplied freely in the shoots of supposedly resistant Sverre plants. Some plants of both cultivars appeared resistant cut in the resistant cultivar Vertus, some plants were susceptible to several isolates. There were at least two pathotypes among the 11 nematode isolates used. In selecting for resistance to lucerne s;em nematode, several nematode isolates should be used and the inoculated plants should be grown to maturity.