Recent wet weather has caused the first flush of black-grass in many fields, but with rain set to continue, it is also increasing the pressure on some growers to consider drilling sooner than perhaps planned.
That will potentially increase the pressure on black-grass herbicides, and make an effective pre-emergence programme even more important.
Black-grass typically has two autumn flushes, the first at the end of September and another from mid-October. In ideal conditions, the best time to drill is after the second flush but wet weather may cause a change in tactics this autumn.
Bayer commercial technical manager Darren Adkins thinks that some farmers may drill earlier than recent seasons to deal with the risk from wet weather.
"We had 100mm of rain in Lincolnshire at the end of September and further rain in October. There is a balancing act between drilling later to control black-grass and drilling earlier to ensure there is a good acreage of winter wheat crop, which on many farms is the most profitable crop,” he says.
“It will partly depend on the forecast, but I think the mindset has shifted to ‘when can I drill?’ from ‘how long can I wait?’. Particularly on heavy land farms I expect drilling to begin at the next break in the weather.”
Further south in Oxfordshire, Bayer’s Ben Giles reports a similar situation but as there has been less rain, he is more confident that farmers will still delay.
“Black-grass flushes finally began at the end of September after 50mm of rain fell in 7 days, I expect most growers will delay until after mid-October because they have first-hand experience of the difference late-drilling makes,” he says.
Another factor to consider is the ADAS black-grass seed dormancy forecast.
It is predicting a higher-dormancy year, most likely pushing the second flush of black-grass towards the end of October. Consequently, even in later drilled crops, there is a danger of further germination, so managing the risk with herbicides and establishment technique is essential.
“The herbicide programme is going to be absolutely critical this season as the weather and dormancy are working against us,” says Mr Adkins.
“Proper timing makes a lot of difference at pre-em. Applying within 48 hours of drilling consistently achieves the best control from Liberator in trials. In a wetter autumn, the big danger is drilling but not being able to spray because it turns wet, so make sure you can get back within 48 hours to spray.”
Other options to manage the risks this autumn include upping the seed rate to encourage establishment of a competitive crop, while minimising disturbance at drilling can help to limit the amount of black-grass germination in the crop.
Early drilling could also have implications for BYDV control says Mr Adkins.
Earlier-drilled crops have more time to accumulate the necessary degree days to require multiple insecticide treatments.
Growers should keep this risk in mind when making the final decision about when to drill.