Rapeseeds sown (drilled, subcast and autocast) in mid-August before the deluge were emerging well, enjoying the friable soil structure and moisture. Now it’s all change and some rape establishment will be delayed. As yet there is no need to panic, early to mid-September sown rapeseed can perform well as long as seed bed conditions are good and not forced.
With the wet weather forecast, some planned herbicides were delayed until early post emergence. Reasonable weed control can still be achieved from the various metazachlor, quinmeric and dimethenamid combinations if these are applied as the majority of cotyledons expand before the weeds germinate. Later applications may be disappointing.
Struggling rapeseed will appreciate some nitrogen (30kgN/ha). If this application is required don’t delay. To maximise its benefit, apply this early whilst the crop is actively growing and able to utilise the nitrogen.
In these moist conditions cereal volunteers will quickly become competitive, aim to take them out swiftly with the first contact graminicide, this may be necessary soon, particularly where the crop follows barley. Where relevant these graminicides can be mixed with the post emergence spray (always check product labels for compatibility).
Slug activity has been low, but don’t be complacent the situation could change quickly. Monitor traps and observe crops and volunteers for damage.
Be aware of the guidelines for metaldehyde stewardship and plan how best to use the 210g/ha of active on each crop this autumn. Early sown wheats will be planted as soon as work can start again. Focus on how to achieve good seedbeds for winter cereals; thankfully soil structure was in excellent condition before the heavy rain.
Good seedbeds are ever more important as grass weed control becomes more challenging. Residual pre-emergence herbicides work best on fine, moist, friable seedbeds. Fields with a history of moderate to heavy black-grass infestation should receive a pre or peri emergence application which includes flufenacet (Crystal and Liberator). No doubt further comment on autumn cereal herbicides will ensue.