Ragwort control with herbicides and fertilisers: first year's results

Abstract

<jats:p>Several combinations of N, P and K fertilisers and the herbicides 2,4-D or glyphosate were tested in conjunction with conservation tillage for ragwort (Senecio jacobaea) control in a low fertility hill country pasture. The trial started in March 1988 and assessments have been made for 12 months. Results so far have shown that development of a dense competitive sward by adequate fertiliser is essential to miuimise the ragwort infestation. The combination of 2,4-D and phosphate fertiliser resulted in the best sward composition and growth, and allowed the least re-invasion of ragwort into the pasture. Keywords Senecio jacobaea, 2,4-D, glyphosate, fertilisers, NPK, chemical control, herbicides, dairy pastures, pasture renovation</jats:p>

Optimising pasture production to minimise weed growth

“…The latter treatment is comparable to a set stocked sheep grazing, while the longer treatment resembles a fast rotational grazing with dairy heifers. Similar effects of pasture height (or residuals) were obtained by Edwards et al (2000) for Californian thistle and by Wardle et al (1992) for nodding thistle, while Thompson & Saunders (1986) and Rahman et al (1990) made similar observations for ragwort in combination with fertilisers. Maintaining a strong sward in autumn when most seedlings emerge (Popay & Thompson 1980) proved a highly effective method to control nodding thistle populations.…”

“…This can be overcome by maintaining pasture heights (residual dry matter) at slightly higher levels to prevent the soil from being exposed to direct radiation and also leaves the plant with more leaf area, speeding up pasture regrowth. Maintaining higher dry matter residuals after grazing is an effective means of preventing weed seedlings from establishing (Rahman et al 1990). The impact of different pasture residuals has been studied over the years for several weeds, eg.…”