Key Points
- Nortron (1.5l/ha pre or post emergence) gave the best control of Poa
- Glyphosate was more effective in controlling Poa at 300ml than 200ml. Neither rate appeared to have a major effect on ryegrass dry matter or seed yield
- The formulation of glyphosate did not influence Poa control or level of damage to the ryegrass
- Glyphosate may complement Nortron for Poa and volunteer cereal control
- Ryegrass cultivars may differ markedly in response to rates and timings of Glyphosate
- All spring applied herbicides reduced the incidence of Poa in a low weed pressure situation. None of these products, except Glyphosate, appeared to have a detrimental effect on ryegrass
- Moddus reduced the incidence of Poa to similar levels as the herbicides and may be useful as a spring treatment if applied after an autumn application of Nortron
- Moddus also increased ryegrass seed yields and, as a result, diluted the percentage of Poa in the seed line