Performance of j2uazifop-butyl against Elymus repens

The effects of irrigation, four fertiliser rates, fungicide, insecticide + molluscicide, and nematicide treatments were tested on an Italian ryegrass sward sown in May 1983, in a multi-factorial experiment that allowed treatment interactions to be examined. Pests and fungal diseases were monitored over a 2-yr period. No recognised grassland insect pests or slugs were found in the seedbed but there were an estimated 17 300 plant parasitic nematodes/litre soil. Other, non-pest invertebrate populations, e.g. earthworms, were not assessed. In the first year yields were increased most by irrigation. There were also large yield responses to fertiliser over the range 50–900 kg N/ha/yr. Responses to pesticide application were relatively small. However, there were significant yield responses in the first year to nematicide and to insecticide + molluscicide treatments. Yields in the second year were affected more by increased fertiliser use than by irrigation; increases after pesticide use were similar to the previous year, and there was also a small but significant yield gain over untreated plots at the second harvest from those treated with fungicide. Interactions between main factors occurred in both years, affecting yields and nematode abundance. Nematode numbers were decreased in both years where the larger, compared to the smaller fertiliser applications had been made. In the first year these differences were only apparent on irrigated plots. It was concluded that, in this trial, irrigation had the greatest effect on yields of spring-sown ryegrass during its establishment year but that increasing fertiliser rates had a greater effect the year after; that fungi had had little effect on ryegrass yields, and that nematodes were more important pests than insects during establishment but insects were more important subsequently.