Spring cereals have plenty to offer – but they move fast, to make them pay, the first 6–8 weeks after drilling are crucial. That’s when weeds compete hardest, and when nitrogen demand begins to build.
Two levers make the biggest difference to final yield and grain quality: weed and disease control and nitrogen timing. Get them right, and you’ll grow tonnes of clean, high-quality grain. Get them wrong, and you’ll be chasing yield all season.
Weed Control: Early Competition Sets the Tone
Cereal crops are competitive once established, but in the first month they’re vulnerable. Weeds that get away early can permanently cut yield potential by shading crops, robbing nitrogen, and pulling moisture.
- Spray early, spray right. Target weeds at the 2–4 leaf stage, while they’re actively growing. Every week you delay reduces control and lets weeds steal yield.
- Coverage matters. Calibrate sprayers, check nozzle selection, and run correct water rates. Patchy coverage now = escapes later.
- Mind your chemistry. Herbicide resistance is a real and growing issue in NZ cereals. Avoid blanket repeats of last year’s product. Rotate modes of action and use mixes to protect chemistry for the long haul.
- Seedbed conditions. Cloddy or dry seedbeds can slow crop emergence, giving weeds a head start. In these cases, even tighter spray timing is essential.
Rule of thumb: a cereal crop that’s weed-free in the first 30 days has the best shot at dominating for the rest of the season.
Nitrogen Timing: Front-Load for Spring Cereals
Spring-sown cereals don’t hang around. Unlike autumn crops that have months to tiller and bulk up before winter, spring crops are racing the clock. That means nitrogen needs to be in the soil early, right from the get-go, to drive canopy growth and tiller numbers.
- At drilling/establishment
Put most of your N on up front. Early vigour sets crop density and tiller survival, which directly drives head numbers per square metre. - Early growth (GS 13–21)
Top up if needed as the crop builds canopy. In NZ conditions, N uptake ramps up quickly as soils warm and crops race through early growth stages. - Stem elongation (GS 30–31)
A lighter split here can keep the canopy green and heads filling, but the heavy lifting should already be done by earlier applications.
Rule of thumb: spring cereals need their fuel in the tank early. If you wait until stem elongation to feed them, you’ve already missed the main window to build yield.
Key Takeaways
- Keep cereals weed-free in the first 30 days to lock in yield potential.
- Spray weeds small, rotate chemistry, and check coverage.
- Apply N early in spring sown crops.
- Calibration of sprayers and spreaders is as important as the products you use.
Want a paddock plan that lines up herbicide strategy with nitrogen timing? Talk to your local Catalyst agronomist. We’ll walk it with you.