10 July 2026

Weed Watch 2026: Final chance for free herbicide resistance testing

Harvest 2026 is an opportune time for cereal growers to collect suspect weed seeds for their own resistance testing - a unique free service from Oak Park. As part of the DAFM-funded EVOLVE project, this is the final opportunity for widespread testing of suspected grass or broadleaf weed populations, according to Teagasc’s Vijaya Bhaskar.

Results from resistance testing since 2019 show a worrying trend:

79% of Italian ryegrass and 64% of blackgrass populations were resistant to ACCase (eg. Axial, Falcon, Stratos, Centurion) and/or ALS (eg. Pacifica, Broadway) herbicides
Three cases of glyphosate-resistant Italian ryegrass have been confirmed
55% of wild oat populations were ACCase-resistant, with one population showing multiple resistance to ALS herbicides
ALS resistance has been confirmed in meadow grasses and a rye brome population
Resistance to broadleaf-active (eg. Cameo Max) or broad-spectrum ALS herbicides has been confirmed in poppy, chickweed, common field-speedwell, corn marigold, and pale persicaria

Growers, agronomists and advisors who currently have identified or suspect grass or broad-leaved weeds in their fields use this unique free testing to determine population status and mitigate using correct herbicide and integrated strategies, including where necessary, drastic actions. Pay attention: especially, where Italian ryegrass, wild oats, blackgrass, rye brome or poppy is present.

A flyer with images of grass weeds in cereal crops overlaid with text: Are your weeds herbicide resistant? Avail of free resistance testing to know best control options to control your suspect weed (grass or broad-leaved) in your tillage crops. For further information, contact your advisor or scan the QR code.

Follow the instructions on the Weed Watch flyer to collect seed samples for testing. For accurate and quick results:

Collect ripe seeds and ensure they are fully dry before storing them in a paper envelope.
Complete the resistance testing form.
Send the completed form and seed samples to Vijaya Bhaskar, Teagasc Crops Research Centre, Oak Park, Carlow.
For queries or if you want your weed population sampled, contact Vijaya Bhaskar (M: 087 060 9409) or Gelu Crisan (M: 086 011 3138).

Don’t ignore the problem. Identifying resistance early will help protect herbicide options and support effective weed control for future seasons.

Map showing the prevalence of herbicide resistant grass weeds, illustrating areas where resistance has been identified in spring wild oats, blackgrass, Italian ryegrass, meadow grass and rye brome

Access the Herbicide Resistance Testing Application Form (PDF)