How to get to grips with herbicide-resistant wild oats
Posted 2 weeks ago
Tales of the chaos caused herbicide-resistant black-grass have been commonplace within the UK’s tillage industry for many years: hence the attempts made by Ireland’s cereal sector to prevent the importation of these ‘uber’ weeds in the first place.
However, it seems that we already have a resistant weed within our midst; one that is capable of drastically reducing cereal across the country.
The culprits come in the form of specific wild oat variants that have mutated in ways that make them resistant to most or all available herbicides.
Advice on herbicide-resistant wild oats
Tillage advisors specifically highlighted the scale of the problem confronting spring barley growers at the latest crops management webinar, hosted by Teagasc this week.
The alignment of the terms ‘spring barley’ and herbicide resistance automatically brings Ireland’s most value added cereal to the front and centre. Malting barley is an inherently profitable crop to grow.
So it makes absolute sense to find ways of dealing effectively with any problems that could be impacting on the sustainability of these enterprises.
How can growers deal with herbicide-resistant wild oats?
Step one is to ascertain if the problem exists in the first place.
This can be achieved by using a standard herbicide approach to deal with the problem. Wild oat plants that survive this approach should be suspected as being resistant.
Confirmation of this can be achieved by sending ripe wild oat seeds to Teagasc Oakpark, where they can be scientifically tested for resistance to a range of herbicides.
This work requires the seeds submitted to be germinated in a laboratory.
Testing work carried out by Teagasc in 2019 confirmed that 20% of the wild oat samples submitted were confirmed with herbicide (ACCase) resistance.
The first problem of this nature was identified in 2016. Significantly, resistance across a range of herbicides has also been identified by Teagasc scientists.
Eliminating the problem, once identified, may require one of a number of approaches to be taken.
Small infestations within a crop can be dealt with by hand, rouging individual wild oat crops before they shed their seed.
However, in fields where heavy infestations of resistant wild oats exist, the only solution is to introduce a number of break crops within a cereal rotation.
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