Early weed control: setting spring barley up for success in dry conditions

As our Head of Crop Production, Mike Thornton, explains, timing and attention to detail can make a real difference.

“With as little as 110 days between drilling and harvest, spring barley doesn’t have time to recover from early competition,” says Mike. “Weeds will quickly rob crops of light, water and nutrients – and can reduce tiller numbers at a critical stage.”

Start clean, stay clean

Ideally, crops are drilled into a well-prepared stale seedbed with minimal weed pressure.

“The majority of spring barley should go into a stale seedbed that’s free from active grass and broad-leaved weeds,” Mike explains. “But we know that’s not always the reality.”

Where problem weeds like blackgrass or annual meadow grass are present, a strong pre-emergence approach is essential.

“In those situations, a multi-active pre-emergence product such as Tower is key,” he says. “Post-emergence options for these weeds are limited, so it’s important to get that early control in place.”

Earlier applications, better results

For weeds that can be tackled post-emergence, our advice is simple: don’t wait.

Studies consistently show the value of early intervention.

“Applications made between GS13 and GS24 deliver the best results,” says Mike. “In fact, treatments at GS13 have shown an average yield benefit of around 2% compared with delaying until GS24 or later.”

That early timing helps remove competition before it impacts crop development – but it’s also about understanding the weeds you’re dealing with.

“Weeds that emerge from depth are less affected by residual chemistry, so early post-emergence treatments become even more important,” he adds. “Later-emerging weeds, on the other hand, are often outcompeted as the crop thickens up.”

Don’t let dry conditions catch you out

Dry springs bring an added challenge – reduced herbicide efficacy.

“In dry conditions, weeds can develop thicker wax layers and keep their stomata closed for longer, which limits herbicide uptake,” Mike explains. “At the same time, slower metabolism reduces the movement of herbicides within the plant.”

That makes early applications even more valuable, while weeds are still small and more susceptible.

We also recommend paying close attention to application technique:

• Spray early in the morning when stomata are more likely to be open
• Avoid cutting rates – robust doses are key in tougher conditions
• Include an adjuvant oil to improve herbicide uptake

“It’s about giving the chemistry the best possible chance to work,” Mike adds.

Choosing the right chemistry

Product choice will depend on weed spectrum, resistance risk and rotation considerations – but there are several strong options available.

“Quelex is a go-to in many post-emergence situations,” says Mike. “Its twin actives provide robust control across a wide range of weeds, including some that are resistant to ALS chemistry.”

For broader spectrum and persistence:

“DP911 SX can extend control, but growers need to be mindful of metsulfuron’s persistence, particularly where oilseed rape is in the rotation.”

Another flexible option is:

“Supreme Max, which brings good activity on species like field pansy and speedwell, with fewer concerns for following brassica crops. It’s also a very useful tank-mix partner.”

For those looking to avoid ALS chemistry altogether:

“Pixarro is a strong alternative and can be paired with a phenoxy product to avoid any issues with following crops,” Mike explains.

And where grassweeds such as ryegrass or wild oats are a concern:

“We’d look to include Kanaster at full rate,” he says. “Timing is important — it can be applied one week before or three weeks after a broad-leaved weed treatment, up to GS41.”

Alternatively:

“Foxtrot is another option, but it has an earlier cut-off at GS31 and needs to be applied on its own.”

Thinking longer term

Even with the best-laid plans, there may still be situations where weeds escape control.

“If patches of weeds aren’t controlled, don’t be afraid to take them out before they set seed,” says Mike. “In some cases, that may mean using glyphosate on problem areas.”

It’s a decision that pays back over time.

“Preventing seed return is critical,” he adds. “Some weed seeds can persist in the soil for 10 years or more, so stopping that cycle is a big win for future crops.”

Setting crops up from the start

In a fast-moving crop like spring barley, early decisions have a lasting impact. Getting weed control right — from pre-emergence through to early post-emergence — is key to protecting yield and maintaining crop momentum.

Ready to tighten up your weed control strategy?

Every field presents a different challenge — from weed spectrum to soil type and drilling conditions.

Speak to your local ProCam agronomist to build a tailored, effective weed control programme and give your spring barley the strongest possible start.