The effect of clover stem eelworm on the establishment of pure swards of white clover

A comparison was made of establishment of five white clover lines sown as pure swards on soil infested with stem eelworm ( Ditylenchus dipsaci ) and on uninfested soil. On infested soil two lines found to be resistant (Morocco × ‘Grasslands 4700’ and Ladino × ‘Grasslands 4700’) showed most rapid establishment and least production loss due to poor establishment. A very susceptible line from Israel suffered severe loss due to eelworm attack, and the varieties ‘Grasslands Huia’ and ‘Grasslands 4700’, known to be of intermediate susceptibility, showed an intermediate loss of production due to the effects of eelworm on establishment. All except the Israeli line recovered from the initial effect of eelworm attack on newly germinated seedlings and within 9 months from sowing were producing as much forage dry matter in the presence as in the absence of eelworm. Recovery was possible by virtue of the sprawling nature of the white clover plant, the rate being related to the proportion of seedlings which survived eelworm attack. This recovery phenomenon may explain the absence of apparent economic eelworm effects in established New Zealand pastures.