As we look forward to longer days and planning for spring herbicide options, now is a good time to evaluate how well the autumn herbicide spray programs have performed.
Generally most Winter OSR was drilled into warm moist seedbeds in August; this was a key factor in getting the crop away quickly reducing the risk of flea beetle damage. Establishment was good nationally; this was good news especially in the Eastern Counties where many crops over the last few years have failed from drought or flea beetle damage.
As crops became well established, there was more confidence to apply early residual herbicides to control broadleaved weeds and many crops have also received a Centurion Max for early black grass contact activity. The key active in residual grass weed control in OSR centres on propyzamide, this active ingredient needs to be used carefully as it is highly soluble but requires moist, cold conditions to perform at its best. Stewardship guidelines need to be followed strictly to minimise run off and leaching into water courses. At the moment the crop has a very dense canopy. What is the best practice for application in current conditions? Over the coming weeks frosty conditions will defoliate the canopy and expose the soil – the target site. However if not, and application is possible, propyzamide can be applied to the foliage and be washed down to the soil. No decision can be made until travelling again is possible.
In cereals the 5 step campaign has led to an increase in the sales of ploughs nationally. Ploughing one year in five buries weed seeds and allows them to deteriorate over this time scale. Drilling later also helps to reduce numbers as stale seedbeds allow early black grass flushes to be controlled. With the continued registration of glyphosate this practice can continue, which will help with longer term improvements to soil management. Wet weather forced late drilling with crops being drilled from early October through to early November. With seedbeds improving the later we drilled, early cloddy seedbeds decisions needed to be made to ensure the residual stacks would perform. Avadex continued to offer an early key role where difficult black grass was an issue, followed by stacks centred round flufenacet. At the time of application there was plenty of moisture and most residual stacks have performed well to date. Any emerged black grass may yet pick up enough residual to either control or suppress growth through to the spring. Further assessments are needed when a contact material may be required to control any grass weeds which have evaded the autumn stack.