Nematode populations and their effects on herbage production in a volcanic plateau pasture

Abstract

Insecticidal rates of carbofuran and oxamyl were applied to a trial at Wairakei to control Argentine stem weevil (Listronotus bonariensis (Kuschel)) in ryegrass (Lolium perenne L.), but herbage responses were greatest in the white clover (Trifolium repens L.) component of the pasture. Autumn samples showed significant reductions in the populations of many nematodes, both vermiform and within roots. Nematodes likely to have been responsible for depressing white clover growth are Meloidogyne hapla, Heterodera trifolii, Paratrichodorus minor, Pratylenchus, and Paratylenchus. Because nematodes were probably largely responsible for the observed response to applied insecticide, care is needed in interpreting results of all such trials. It was not possible' to partition the effects of the various nematodes on pasture production.

Keywords:

• nematodes
• populations
• insecticides
• oxamyl
• pastures
• legumes