Resistance of the white clover variety G49 and its parent lines to stem nematode (Ditylenchus dipsaci)

Abstract

Abstract Stem nematode (Ditylenchus dipsaci) infection of white clover variety G49 was compared to that of other white clover lines in two experiments. The G49 parent lines were also screened for infection in a third experiment. Symptoms of stem nematode infection were assessed at 8, 14, and 21 days after inoculation. The lower infection rate of G49 by D. dipsaci was not sufficient, as a stand‐alone trait, to distinguish G49 from other existing lines. However, G49 had a significantly lower infection rate than Pitau so these can be distinguished for the purposes of a Plant Variety Right application. The variation among the parent lines of G49 indicated scope for further selection to improve resistance. Three techniques for applying inoculum to seedlings were compared; the best one uses 1 ml of nematode suspension placed over a 3‐day‐old seedling lying on the surface of peat‐based potting mix which is then lightly covered.