Cereal agronomy March: T0 rust, black grass top ups and N timing

The reality this month: under pressure, you decide

Growers and agronomists are relying on each other to call the critical passes. It’s wet, spray windows are short, and crops are forward. Bayer Technical Manager for the East, Ellie Borthwick-North’s view is straightforward: don’t let early season hesitation cap potential. If a short, bright window appears, use it; especially for jobs that debottleneck the next fortnight.

“Everything may come at once; nutrition, T0, and in places a spring ‘meso’. Getting the right pass done at the right moment takes pressure out of the system.”

1) Travel & timing: use short windows to ease the bottleneck

• Ground conditions: It’s currently too wet to travel but longer-range forecasts suggest mild spells are on the way. If this happens, then catching that one sunny afternoon can be enough to clear a priority job.

• Workload logic: Target headlands or prioritising field by field now, can help spread the pressure of simultaneous deadlines occurring in the middle of the “perfect” weather window.

• Sprayer organisation: Remember the hidden time costs (washouts, nozzle/tyre swaps, mounted/trailered changeovers). Plan in half day chunks to avoid midday kit changes.

• Prioritise passes: that unlock capacity later (e.g. black grass in the headlands).

Ellie: “If a good afternoon appears, get on. Hitting the right timing now reduces time budget tension later.”

2) Early disease: barley mildew now; yellow rust at T0 (field by field)

• Forward crops: Winter barley is carrying mildew in places. Where you judge intervention is called for, consider mildew active options and timings that limit crop check.

• T0 in wheat: With yellow rust risk on the radar, agronomists will likely be choosing a tebuconazole based T0 in susceptible situations.

• Sequencing: Where a spring ALS grass weed pass (e.g., mesosulfuron based) is also planned, allow a sensible gap (~7–14 days) between that and azole/fungicide work where practical to reduce stress. Always follow label guidance and best practice.

Where certain tools can fit (if you decide they’re called for):

• For barley mildew pressure, mixes that include spiroxamine and azole partners (e.g., Cello®: prothioconazole + spiroxamine + tebuconazole) offer targeted activity.

• For T0 rust where you judge it necessary, tebuconazole options (e.g., Folicur®; or mixed with prothioconazole as in Kestrel®) remain familiar tools.

• Adjust to the season: Keep plans malleable, if the weather turns dry for 4–6 weeks, revisit priorities and sequences accordingly.

Ellie: “We’ll likely need to invest a bit more smartly at T1 than last season because background pressure is higher due to earlier drilling. with commodity prices where they are we can’t afford to let our foot off the pedal in regard to chasing yield.”

3) Black grass: targeted spring mesosulfuron still has a place

• What Ellie’s seeing: Residual stacks generally worked well in the autumn, but early drilled, high-risk fields show isolated escapees, often on headlands.

• Decision lens: Even 30–40% removal of surviving plants can materially cut seed return into the autumn, that’s future pressure avoided.

• Field by field: Don’t generalise one resistance test across a whole block. Populations vary; some are still parts susceptible to ALS chemistry.

• Tactical passes: Headlands only or limited area treatments can be a smart use of a short weather window and reduce workload later.

If you opt for a spring ALS pass: Mesosulfuron‑based options (e.g., Atlantis® OD; Atlantis® Star adds thiencarbazone; Pacifica® Plus includes amidosulfuron + iodosulfuron + mesosulfuron) are familiar tools for targeted clean‑ups where susceptibility and crop condition allow. Observe labels, varieties, spray conditions and interval guidance.

Ellie: “We sometimes assume ‘Atlantis is done’ everywhere. It isn’t. There are still fields and headlands where it contributes, especially if you’re preventing a multiyear buildup.”

4) Nutrition & cashflow: protect potential

• Nitrogen timing: Some fields are already looking hungry; forward canopies will shed tillers without prompt nutrition.

• Budget reality: Input spend is under scrutiny, but protected yield is protected margin in most scenarios. Early under‑investment at T0 and T1 can lock in a ceiling you can’t remove later.

Practical planning tips Ellie emphasises.

• Plan in half day blocks to avoid unnecessary kit swaps.

• Use short windows to clear headlands or single field jobs.

• Sequence sensibly when ALS herbicides and T0 are close (gap where you can; check labels).

• Stay flexible, be ready to pivot if March turns dry.

We’re here to support your judgement

If you want to compare notes on local conditions or sense check a timing/sequence, your local CTM is available for a straight, no pressure discussion. You make the decisions, we’ll back you up with field experience, data and practical options.

Cello® contains prothioconazole, spiroxamine and tebuconazole. Folicur® contains tebuconazole. Kestrel® contains prothioconazole and tebuconazole. Atlantis® OD contains mesosulfuron-methyl and iodosulfuron-methyl-sodium. Atlantis® Star contains mesosulfuron-methyl, iodosulfuron-methyl-sodium and thiencarbazone-methyl. Pacifica® Plus contains amidosulfuron, iodosulfuron-methyl-sodium and mesosulfuron-methyl. Cello, Folicur, Kestrel, Atlantis and Pacifica are registered trademarks of Bayer. All other brand names used are Trademarks of other manufacturers in which proprietary rights may exist. Use plant protection products safely. Always read the label and product information before use. Pay attention to the risk indications and follow the safety precautions on the label. For further information, including contact details, visit www.cropscience.bayer.co.uk or call 0808 1969522. © Bayer CropScience Limited 2026