Integrated weed management in cereals: Planning for autumn success
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Effective weed management is a year-round challenge – especially with persistent threats like Italian ryegrass, bromes and difficult broad-leaved weeds such as groundsel, poppy, cleavers and many others.
Early establishing weeds can significantly reduce yield, complicate harvest, and impact future rotations. Wet autumns and limited spray windows in recent seasons have only intensified the problem.
A proactive, integrated approach combining cultural and chemical strategies is essential. This includes:
Cultural controls: Delayed drilling, stale seedbeds, variety choice and seed rate, cultivations and crop rotation.
Non-chemical methods: Stubble management and targeted cultivations.
Chemical control: Timely herbicide applications tailored to weed species and appropriate growth stages.
Building an autumn herbicide strategy
A successful herbicide programme begins with clear planning:
- Identify target weeds – Focus on species that threaten yield or crop quality.
- Understand weed biology – Know when each species emerges and competes, and exploit weaknesses in their biology with an effective herbicide programme.
- Select appropriate chemistry – Match actives to weed spectrum and timing.
- Use sequences and mixtures – Combine a pre-emergence spray with sequential follow-up sprays to maintain residual activity and aim to diversify modes of action to reduce selection pressure and support resistance management.
Italian ryegrass is highly competitive grass weed, prolific in seed production, and increasingly resistant to herbicides.
Corteva trials have shown the importance of a strong foundation in the Autumn, by using a good residual such as flufenacet, pendimethalin or prosulfocarb.
A sequenced approach is key. Follow pre-emergence sprays with one or two top-up applications. Pyroxsulam-based products such as Broadway® Star applied at the 1-3 leaf stage offer strong post-emergence control, especially when tank-mixed with residuals. Timing is critical: autumn-emerging ryegrass can produce 23 times more seed than spring-germinating plants, making early intervention vital.
Bromes are increasingly problematic due to reduced tillage, tight rotations, and limited herbicide options. Their physical traits, including leaf hairs, waxy surfaces, and complex architecture can reduce herbicide uptake. Effective control involves a two- to three-spray programme targeting small, emerged plants (1-3 leaf stage).
Key actives include flufenacet, triallate (pre-emergence only), and pendimethalin, with pyroxsulam offering strong post-emergence efficacy when conditions support active growth.
Make the most of all herbicide applications:
- For residual herbicides, timing is critical: Apply an effective pre-emergence spray within 48 hours of drilling onto a firm, fine and moist seedbed.
- Post-emergence contact herbicides: Begin applications once grass weeds reach growth stage GS10 or beyond, making sure the weeds are actively growing and leaves are dry for the best absorption. Always include an approved adjuvant with your spray.
- Pay close attention to application techniques - selecting the right nozzles, adjusting water rates, and choosing favourable conditions can significantly enhance overall efficacy.
Don’t forget about difficult broad-leaved weeds such as groundsel, poppy, cleavers, umbelliferous species, fumitory and volunteer crops.
Groundsel, a fast-growing weed from the Daisy family, was difficult to control last season, due to its rapid growth and high seed return. It can complete its lifecycle in as little as 18 days and germinates year-round, often producing multiple generations per season. Effective control is challenging once it matures, as herbicide absorption decreases. For best results, herbicides should be applied early at the germination to 6 true leaf stage.
Poppies, especially if ALS resistant, must be controlled using a full programme approach.
- Use a pre-em containing pendimethylin followed by Zypar® @ 0.75 L/ha in the autumn @ 2-4 true leaves of the weed.
- Add Picolinafen for difficult or large populations.
Other notable late autumn / early spring weeds that should be prioritised for control include cleavers, chickweed, fumitory and mayweeds. All are controlled by Zypar or Broadway® Star applied late autumn or early spring.
"Effective weed management is a year-round challenge, especially with persistent threats like Italian ryegrass, bromes and difficult broad-leaved weeds. Early intervention and a proactive, integrated approach combining cultural and chemical strategies are essential. At Corteva, we emphasise clear planning, understanding weed biology, and using a sequenced approach to control highly competitive weeds, ensuring optimal yield and crop quality."
Liz Glynn, National Field Technical Manager Ireland.
Useful information
For more info call our Technical hotline: +448006898899 or email: ukhotline@corteva.com
Product information:
Broadway Star
Zypar
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