Helicotylenchus dihystera in Australian cotton roots.

We report for the first time in Australia, observation of the plant-parasitic nematode Helicotylenchus dihystera within roots of cotton (Gossipium hirsutum). The incidence of this and other nematodes in cotton roots did not correlate with the incidence of Verticillium wilt that was present within the same crops. The lack of reports of plant-parasitic nematodes in cotton in Australia has previously been attributed to the high clay content of the soils used to grow cotton. Our observations indicate that these heavy soils do not preclude the survival of plant-parasitic nematodes on cotton and reinforce the importance of quarantine and farm hygiene practices.