There is little doubt the exceptionally wet autumn and winter in 2019/20 will be remembered for years to come. The national winter wheat area was approximately 35% lower than harvest 2019. But in the worst-affected parts of the Midlands, Yorkshire and Lincolnshire entire farms had no winter cereals.
After such a difficult season, farmers will be keen have a large area of winter wheat this season, but should they drill early or does it simply increase the risk from black-grass and barley yellow dwarf virus (BYDV)?
“The winter wheat area was approximately 1.1 to 1.2 million hectares in 2019/20, a drop of about 650,000 hectares from harvest 2019,” says Graham Redman of The Anderson’s Centre. “Similar dips were seen after other difficult autumns; with a drop of half a million hectares after 2000, 300,000 after 2008 and 400,000 after 2012. Nationally, the weather from September to February was poorest this year compared to these other years.”
Winter wheat is consistently the best-performing crop on many arable farms. According to Farm Business Survey data, recent gross margins range from £641/ha in 2015 to £959/ha in 2018 mainly driven by global grain prices. After a difficult 2019/20, some farmers are understandably concerned about cash-flow, so planting a large area of the most profitable crop is a logical step for securing farm finances.
Last autumn, large areas of wheat couldn’t be drilled in October because of rain and many crops that were drilled struggled to establish properly. With this in mind, starting to drill wheat earlier in the autumn is an obvious step to reduce the risk of crops not getting drilled at all.
In addition to the peace of mind gained from planting the crop in early autumn, there are potential yield benefits. Research based on 82 AHDB Recommended List trials in Eastern England from 2010–2014 showed a 0.27% yield loss for every day drilling is delayed after 1 September in a weed-free situation with no other agronomic issues. In a farm situation, this means an 8.1% yield loss from delaying from 20 September until 20 October, equivalent to approximately 1 tonne/ha.
Without grass weed pressure and the threat from barley yellow dwarf virus (BYDV), earlier drilling would be a more straightforward decision. But farmers have pushed back drilling dates for a reason, so pulling them forward again is risky as the possible benefits may well be dwarfed by the likely losses from a combination of black-grass, BYDV and increased disease pressure.
Cambridgeshire Farmer Leonard Stamper has successfully managed the black-grass problem with later drilling and shallower cultivation. However, to ensure wheat area he expects some land will be drilled earlier than ideal for black-grass control this autumn.
“We only got a small percentage of wheat drilled last year because of the wet weather. We drilled spring beans and spring barley instead, but this year we are intending to drill a large area of wheat. We need a better year in 2021 to get some cash in the bank, so a good wheat crop is essential.”
Agronomist Peter Brumpton thinks that farmers need to be wary of extensive early drilling. Working in the East Midlands he was in one of the worst affected parts of the country. “The advice for black-grass control hasn’t changed; drilling wheat from mid-October onwards is hugely beneficial.
“Last autumn was about as bad as you can imagine in this part of the country, so I understand why farmers may be thinking about drilling earlier to ensure they have a large wheat area next year.
“But if you plan to drill early on black-grass land, prepare to drill twice because a bad infestation will mean it is not worth keeping the crop. Also, where the crop does come through without excessive black-grass, you may have to spend more on herbicides and BYDV control, so it’s questionable whether it is the most profitable time to drill.”
Research findings reinforce this view, especially in bad black-grass areas. An AHDB commissioned study from 2016 showed that 100 black-grass heads/ m2 causes 1.08 tonnes of lost yield. As black-grass typically has 5–10 tillers, plant counts of just 10–20 /m2 are enough to lose more than 1 tonne in yield, thereby wiping out any potential benefit from earlier sowing. There is also a long-term dimension, increased black-grass numbers from early drilling will result in higher seed return and greater potential problems in future.
A second benefit of later drilling is that pre-emergence herbicides typically perform better at later applications dates. Increased soil moisture improves mobility of actives like flufenacet in the soil and residual herbicides persist for longer in cooler temperatures. Pre-ems are still beneficial for crops following earlier drilling, but suitable application conditions are important.
“Where cereals are drilled in September, a good quality seedbed to ensure good establishment and pre-em performance is vital,” says Mr Brumpton. “Herbicides need to be applied at the true pre-em timing to give the crop a chance of competing with weeds.”
Despite a difficult 2019 where no winter cereals were drilled, Leicestershire farmer Ben Stroud is sticking with what worked in previous years to control black-grass. Since he returned to work on the farm about 10 years ago, he has managed to get control of black-grass by using a traffic light system to score fields and keep a record of black-grass problems.
“Oilseed rape and lucerne both failed and once the wet weather set in from mid-September, we didn’t attempt to drill winter cereals. Lots of farms in this area were in a similar position due to soil type and the sheer quantity of rain.
“The whole farm was drilled in spring and we decided to treat the situation as an opportunity for grass weed control rather than bemoan the situation. Obviously, we need profitable winter wheat back in the rotation, but spring crops are the best way to sort out grass weed problems in my experience.
“We don’t drill winter wheat until the 15 October across the whole farm to make sure black-grass doesn’t become more of a problem. I always monitor stale seedbeds and the main flush of black-grass seems to be between 5–10 October.”
Throughout autumn, Mr Stroud drills cleaner fields first and the most problematic last, which can switch to a spring crop if the weather turns. “Even after repeated spring crops, I don’t think you can consider a field ‘clean’; black-grass seems to come back. That’s why I look at my records to get an idea of the historic grass weed pressure.”
Once wheat is drilled, Mr Stroud keeps the herbicide relatively simple. “We aim for a robust herbicide at the right time, well applied with good soil moisture.
“Liberator (flufenacet + diflufenican) has been our go-to option in recent years. I don’t think you get a huge amount of additional benefit from stacking numerous products; cultural controls are far more useful overall, so we focus on one effective herbicide application.”
This article is adapted from an article that appeared in Bayer Crop Focus magazine.
The AF Group / Bayer joint 5x5 Project to monitor black-grass control is coming to a close later this year. The project has helped the participating farmers find rotations that keep black-grass under control.
At Bayer, we’re committed to giving you the best advice, insight and support to help you get the most from every crop. And this autumn we’re bringing together all the information you need to gain a critical advantage on all aspects of your winter cereals.