Resistance testing is essential - it determines which herbicides are still effective and which are not, allowing for informed decision-making and where necessary, the implementation of strict zero-tolerance measures, writes Vijaya Bhaskar, Teagasc Weed Researcher.

As part of the DAFM-funded EVOLVE project, Teagasc is offering a free weed seed resistance testing service for a limited time. We strongly encourage growers and industry to take advantage of this opportunity to test weed populations that are suspected or difficult to control.

For successful testing, good sample collection is crucial (Figure 1). You can access the Herbicide Resistance Testing Application Form here, or by scanning the QR code at the end of this article.

Figure 1: Viable seeds from all weed populations will be grown in a glasshouse and sprayed using a precision track sprayer. The full label rates of ACCase, ALS, hormone or glyphosate herbicides will be applied at the 2-4 leaf stage for grass weeds and the 4-6 leaf stage for broadleaf weeds. Test results will then be provided directly to the grower or agronomist who submitted the samples, enabling informed, tailored weed management decisions. The full process typically takes 8 to 10 weeks, depending on the quality of the samples.

To date we have confirmed herbicide resistance in nine weed species (5 grass and 4 broadleaf) with varying resistance patterns (see Table 1).

Table 1. Confirmed herbicide-resistant grass and broadleaf weeds in Ireland

Act now to ensure effective weed management for the next season and beyond.

You can access the resistance testing form by scanning the QR code below.