Effect of root nematodes on the growth of seedling and established white clover on a yellow-brown loam

Abstract

The effects of the parasitic root nematodes Heterodera trifolii (clover cyst nematode) and Meloidogyne hapla (root-knot nematode) on ‘Huia’ white clover were investigated in two greenhouse experiments on Egmont brown loam, a yellow-brown loam from Taranaki. Nematodes had a marked effect on the growth of seedling white clover. Over a 50-day period dry matter yield in unsterilised soil was 20% in the 0 to 10 cm soil depth, and 30% in the 10 to 20 cm soil depth, of clover grown in soil that had been sterilised with methyl bromide. The effects of nematodes on white clover at establishment were alleviated in part by the addition of lime equivalent to 2.2 tonnes of CaCO3 per hectare. White clover that had been established in sterilised soil in the absence of nematodes and then transferred to unsterilised soil was also susceptible to attack by nematodes. Over an 80-day growth period dry matter production of white clover in the presence of nematodes was 50% of that of clover grown on sterilised soil. These results are discussed in relation to the field establishment of white clover. An outline of the life history and effects on plants of these two nematode species is given in the Appendix.