With potential repercussions of early drilling last autumn raising concerns regarding grassweed control on some farms, how do growers perceive the threat and what have they been doing to keep on top of populations? CPM asks its readers for their thoughts during this year’s grassweed survey.
“How much are our systems being driven by a need to control grassweeds? That is the question.” DR WILL SMITH
By Janine Adamson
For two consecutive years, grassweed control seems to have been effective, but the problem is far from solved, believes ADAS’ Dr Will Smith. For one, a general shift towards earlier drilling last autumn may have somewhat compromised long-term efforts, equally, the pressure to cut input costs continues to weigh heavy.
To better understand the reality on-farm rather than simply hypothesise, CPM and BASF asked a sample of growers and agronomists to share their thoughts by filling in a survey – an annual questionnaire aimed at reviewing current weed management strategies.
While the year-on-year results are both positive and reasonably consistent, Will says the data does indicate the scale may have tipped marginally into the weeds’ favour this past autumn. “30% of growers said they drilled their winter wheat in the second two weeks of September 2025, which would suggest a slight move towards planting earlier than we’ve seen in previous surveys.
“Of course, the fundamentals of weed management indicate the consequence of this can be negative, but equally, the same can be said for those drilling on the edge of too late and into November. The positive is, 68% planted in October, which means messaging regarding optimum drilling dates for grassweed management is still working,” he explains.
BASF’s cereal herbicide business development manager, Stuart Kevis, adds that conditions last autumn were conducive to drilling in September, with many hoping to avoid missing the boat, as experienced in 2023.
“But from a pure weed management perspective, delayed drilling is the most impactful action to help manage grassweeds, otherwise it places a lot of pressure on chemistry,” he raises. “This is especially the case in fields with the worst weed pressure.”
Finding the optimum balance between drilling date and weed control is something that Ceres Rural agronomist Jock Willmott says is underpinned by risk management. “For some, Harvest 2025 was the lowest yielding year on record because the preceding autumn was awful. So when it came to autumn 2025 drilling, growers went for it knowing they’d have to live with the subsequent grassweeds. They just didn’t want to risk not getting the crop well established,” he explains.
Looking at perceived pressure on a per-weed basis, at the time the survey was conducted in July, participants shared that 34% of their winter wheat cropping area had blackgrass present, an increase of 6% on the previous year. Ryegrass came in at 14% (+1%) and brome at 17% (+1%). While relatively minor for the latter two weeds, Stuart raises it does suggest a gradual change.
“Both ryegrass and brome continue to increase in prevalence on-farm. Equally, the rise in year-on-year blackgrass is more significant, and should remind growers that grassweeds aren’t a one-year problem.
“Some fields might not have been winter wheat last year so we may be bringing higher pressure areas back into the rotation. This is because crops such as oilseed rape, barley and beans can easily mask grassweeds under their canopies. Also, it could of course be a result of the increase in earlier drilling,” he proposes.
In a similar question, growers were asked to describe the overall weed pressure in their winter wheat compared with the same time last year, selecting from much higher pressure through to much lower.
Drawing a broad hypothesis, Will says the number of participants that said ‘much higher pressure than last year’ equates to a similar percentage to those who’d share they’d drilled crops in September. “This shows we that we have to balance drilling date versus weed pressure, hence the scale may have been tipped in the wrong direction,” he suggests.
Will also notes that while the blackgrass control ‘recipe’ is well understood, there’s still much to be learned regarding ryegrass and brome. “With these weeds increasing in populations, we probably should reaffirm what it means to keep them successfully at bay.”
For Stuart, a difficult spring may have meant controlling weed survivors with contact chemistry wasn’t necessarily successful. “Most talk during the autumn was that growers were happy with their pre-emergence herbicide applications, but February was wet and then conditions turned dry very quickly. We know in-crop herbicides are less effective anyway, so top-ups may have struggled.
“It’s important to recognise that we also have higher levels of resistant blackgrass in the UK compared with other countries. The weeds are simply tougher,” he adds.
Considering the financial implications, 57% of survey participants shared that they believe they’ve lost winter wheat yield this year due to grassweeds, with 13% strongly agreeing with the statement. Stuart queries what’s understood by yield loss: “Unfortunately, unless 100% control is achieved throughout the growing cycle, yield will have been lost to a degree or so.
“This is because if reactive action such as rogueing or spraying off high pressure areas took place, then the damage has very much already been done. Weeds are competitive with the crop from day 1,” he stresses.
Will agrees, stating that while most growers evidently connect poor grassweed management with yield loss, the discussion is more complex. “How much are our systems being driven by a need to control grassweeds? That is the question.
“The cost of weed management isn’t just the loss of yield in a single year, rather it must include the legacy of not achieving sufficient control – a change in cropping plans or additional cultivations to remove seeds from the system. This larger cost around grassweed management isn’t always fully considered,” he argues.
For Jock, regarding potential yield loss, more will become apparent after harvest. “But even so, more than half of those surveyed are recognising that their grassweed problem equates to competition and therefore potential yield loss, which unfortunately is the stark reality.”
Looking at application timeliness, the survey reveals that in autumn 2025, 81% of growers were able to apply their planned pre-emergence herbicides on-time, compared with 70% from the season prior. According to Stuart, this is unsurprising given the improved autumn conditions.
“I suppose the only query is what products were actually used to achieve an optimum level of control,” he comments. “The first grassweed flush is always the most significant; there’s also the risk that the first application ends up being your only chance if inclement weather then occurs.”
Will advises growers to take time to reflect on what factors came together to enable that timeliness. “Of course external conditions play a key role, but equally, how did you approach this important component of weed management? Did you do anything differently to prepare in readiness for a good spray day? It all adds up and should be factored into the plan so the good work can be repeated.”
When asked about in-crop IPM techniques implemented pre-harvest 2025 versus those used this year, the data remains static across the likes of rogueing, spraying off worst patches, mapping high pressure areas and spraying off whole fields.
However, for preventative IPM measures, it’s a slightly different story. Versus this year, more growers said they intend to delay drilling (+8%) and rotationally plough (+7%) ahead of this upcoming season.
Will notes that ploughing is an effective technique for brome control, while the increase in later drilling is likely in response to current weed pressures. “It’s all relative – drill early and weeds increase, therefore the next year’s crops have to be planted later to maximise the stale seedbed and get back on top of control.”
Jock agrees: “The most effective control method for brome is ploughing, and growers may feel that more of these weed species are starting to creep into rotations. There’s only so much you can achieve with pre-em chemistry for brome, so to me, this is no surprise.”
According to Stuart, what’s most encouraging is that just 2% of those surveyed have no intention of undertaking any preventative IPM measure for grassweed management. “So nearly everyone is aiming to do something, which is very positive. Not only is this having a significant impact on reducing weed populations, but it also reduces the pressure on essential chemistry,” he highlights.
As for specific herbicide products, the quantity of growers using Luxinum Plus (Luximo (cinmethylin)), continues to rise. In fact, 64% of those surveyed said they’d used it in their winter wheat area this season, compared with 60% last year. For Jock, this is again unsurprising. “With the earlier drilling, growers knew the risk and that they’d likely require an insurance policy, in this case, quality chemistry. Cinmethylin-based products are currently the best.”
Stuart believes the product has established itself as the backbone of cereal herbicide programmes. “It’s best-in-class and has consistently been proven as the most effective chemistry for in-crop weed control. Programmes are built around it; for many, it’s a non-negotiable,” he proposes.
He does, however, raise that while it can be downplayed, Luximo is effective at controlling autumn-germinating sterile brome too. “Residual control of these types of weeds is more difficult, but Luximo does offer activity.”
Will adds that he recognises why the product has become a success. “It’s the strongest single component currently available so it’s understandable that it’s become popular. I just wouldn’t lose sight of the importance of supporting it with both cultural control methods and alternative modes of action within the herbicide stack.”
This is a point that Jock reinforces: “We’re lucky to have Luximo in our armoury and we desperately want to keep it that way, so I’m conscious that we don’t break the chemistry,” he concludes.
This article was taken from the latest issue of CPM. Read the article in full here.
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