Influence of repeated oxamyl application on nematode populations beneath 4 ryegrass cultivars on a yellow-brown loam

Abstract

Plots in a grazed trial in which 4 ryegrass cultivars received regular insecticidal applications of oxamyl were sampled at about 2-month intervals from September 1981 to May 1983 and generic nematode populations assessed. Significant treatment, sampling time, block, and cultivar effects were found. Oxamyl reduced most nematode populations, including Heterodera, Meloidogyne, Heticotylenchus, Paratylenchus, and Pungentus, possibly contributing to increased herbage production and influencing sward composition. The greatest cultivar effect was depression qf Paratylenchus beneath the low-yielding ‘Grasslands Manawa’. There was no evidence of nematodes developing tolerance to oxamyl, and population reduction occurred to 90 cm depth.

Keywords:

• nematodes
• populations
• ryegrass
• cultivars
• insecticides
• nematicides
• Paratylenchus
• Horotiu soil