With autumn 2023 still fresh in minds and harvest likely to fall earlier this year, delaying drilling may prove hard for many, placing additional pressure on herbicide programmes and weed control approaches. CPM hosts this month’s Common Ground discussion to explore further.
“Blackgrass can escalate rather quickly but take years to get back on-track.” JENNY DEAKIN
By Janine Adamson
Conditions during the past few seasons have been extreme – from the waterlogged autumn of 2023 to the prolonged drought this spring – thus having a profound impact on cropping plans and management approaches.
Among the most notable of consequences has been compromised grassweed control, with some growers finding themselves set back around five years. In certain instances this has meant a return to the plough, whereas in others a solution has been found by exploring new chemistry.
Regardless of the tactics deployed, there’s a common theme: taking a zero tolerance view on grassweeds. To discuss this approach further, CPM brings together Doncaster-based farmer, Nigel Durdy; Niab’s regional agronomist for the west,Poppy de Pass; and BASF agronomy manager, Jenny Deakin.
BASIS-qualified Nigel manages 1100ha Ninevah Farm in partnership with his brother Adrian. The farm has a wide range of soil types from blow-away sand to peat, loams and boulder clay. Winter wheat, winter rye, spring barley, vining peas and SFI forms an average cropping rotation.
Integrated weed control
To set the scene, Nigel shared that while he believes the farm is in a good position in terms of grassweed pressure now, that’s not always been the case. “If I look back 8-10 years ago, we were really struggling with blackgrass and losing yield as a result.
“Our cropping was based on winter wheat plus oilseed rape as a break crop, with little spring cropping. Things have changed in many ways since, but one of the key aspects is we’ve adjusted our rotation.”
He explained that as such, the farm hasn’t grown OSR for at least four years, making a shift towards spring cropping, primarily spring barley. “After a blackgrass infested crop of winter wheat, we opted for spring barley which provided a strong start in cleaning that particular field up; that’s been the strategy since.
“Then as an alternative break crop we’ve gone quite strongly into SFI, so when we drill this autumn, we’ll follow that with a summer fallow which should have a positive effect on our blackgrass count. We then add appropriate chemistry such as pre- and post-ems as required, although our cultural methods are definitely helping.”
Poppy added that she’s noted ploughing starting to creep back into more rotations, albeit quietly. “Perhaps some don’t want to talk about it but it’s definitely happening – using the plough to rectify grassweed problems as part of the wider system, rather than dismissed as not required anymore.”
Zero tolerance
Reflecting on the importance of effective grassweed control, Poppy said last year proved a sage reminder due to the increased incidences of ergot. “A lot of blackgrass came through in thinner crops and open canopies, there was then a knock-on effect of ergot. Growers are still cleaning ergot out of crops even at this point now as grain goes out of the shed.
“So from that point of view, zero tolerance is at the forefront to avoid a repeat of that scenario, therefore reducing that weed burden in the seedbank has to be done.
“Looking at crops this year, I’ve found my first ergot in barley, which I’m of course disappointed about. However, it’s brought it to the front of my attention when planning for next year.”
She highlighted that not only do grassweeds impact yield, but they can also waste valuable inputs. “For example, fertiliser that will actually end up feeding a blackgrass crop. All those little things add up and are taking away from your final margin.”
Jenny added that even where pressure is low and rogueable, the seed return can soon multiply. “If we take one plant which perhaps on average has 10 heads – if that was to shed seeds into next year, that will quickly multiply to perhaps 1000 weed seeds. It can escalate rather quickly but take years to get back on-track.
“It may be tempting to take a risk with fewer cultural controls or a less-effective herbicide programme. In these cases though, we’ve seen many live to regret it when a much higher weed count rears its head in the spring.”
This autumn
With the poor autumn conditions of 2023 still relatively fresh in minds, and the prospect of an upcoming early harvest following an arid spring, Jenny said she anticipates some growers may chance drilling in September this season.
“That’s going to be a significant risk because there won’t be the opportunity to achieve adequate stale seedbeds and a good weed seed chit. Planting in September, you may achieve the first flush – which is often the most successful – but that’s still leaning hard on chemistry.”
In response, Poppy explained that she’s trying to keep options flexible for her growers when planning for the upcoming season. “Either way, it’s key to know which blocks of land are lower pressure and harder to drill in wet conditions so you can focus on those first if necessary, and then follow with areas which are more likely to establish successfully later in the season.
“Equally, seed rates are a key measure in combatting blackgrass – are your current rates right or should we push higher to increase crop competition?
“From an agronomist’s point of view, we aim for October drilling onwards to reduce blackgrass pressure, but at the same time, we don’t want crop establishment failure when it’s no longer sensible or possible to travel due to conditions. It’s a compromise of all of those factors and trying to achieve the optimum,” she said.
Poppy highlighted that when comparing fields drilled in September 2024 with those planted in the first week of November, the difference in blackgrass control should prove a good reminder of the importance of drilling date. “The majority of what we’ve looked at this year has been November drilled onwards so it’s been fairly clean, but there are a few early drilled reminders out there, even when input spend has been high.”
Luximo
Moving onto herbicide options, Jenny pointed out that for many, Luximo (cinmethylin) has become the main building block at pre-emergence in a herbicide programme. “It’s delivered high levels of control and been well received, but there are wider aspects to consider in order to achieve those good results and ensure crop safety.
“Factors such as ensuring correct drilling depth, and a good consolidation by rolling – admittedly that’s been difficult the past few seasons due to conditions.
“BASF trials show Luximo consistently provides an uplift in control. It does a lot of the heavy lifting in a programme, so it’s important everything is done to maximise its performance.”
She added that, while it provides the most value as the first product on the ground, as confirmed last autumn, the flexibility of Luximo’s label has proven useful. “There was a small drilling window in September but then there wasn’t an opportunity until November; having that flexibility to go post-em was helpful.
“But, it’s still not going to be a silver bullet if you’re drilling in September. Yes, it will be effective, but it’s not going to fully control all grassweeds present in the seedbank.”
Jenny highlighted the uncertainty surrounding flufenacet. “In the past, growers have relied on flufenacet being a solid mode of action and useful as a top-up for weed control. It’s now up in the air therefore it could be valuable to use the transition period to get used to Luximo and where it fits within herbicide programmes.”
In agreement, Poppy said using contact herbicides in the spring in a bid to control established blackgrass, is often hit and miss. “So the more we can do in the autumn, generally, the better.
“It’s taken a year or two for farmers to get to know Luximo, considering they’ve been using it during some very testing conditions, but it’s very helpful to have another solid building block in the armoury. Equally, due to its effectiveness, it must be used with care when conditions are diminishing.”
Providing a farmer’s perspective, Nigel believes it’s been a game-changer. “We wanted something new, something extra, and when we lose flufenacet we’ll require other products to rely on.
“Equally, I agree that it has to be used properly to be fully efficacious – including attention to detail during application and adequate moisture in the seedbed. But used correctly, it should do the job meaning you have a chance of achieving a fairly clean wheat crop.
“We’ve always managed to apply it in reasonable conditions with the seed depth good enough for it not to show any adverse effect. It’s a good product.”
This article was taken from the latest issue of CPM. Read the article in full here.
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