Teagasc is appealing to farmers, and the general public, “not to sow wildflower seeds on or near farmland” following the discovery of the invasive blackgrass weed in an experimental plot at Oak Park Research Centre.

Michael Hennessy head of the Crops Knowledge Transfer Department said “all we can do is assume that batch of contaminated wildflower seed was made from similar batches with blackgrass in it” which, he says, poses a “significant threat to the tillage sector”.

“Blackgrass is a weed with enormous capacity to produce thousands of seeds - once it gets going on a farm, because the seeds are so small, it’s very easy to spread.

“Within three years it can be absolutely endemic and very difficult to clear, almost impossible,” he said, adding that the contaminated mix was sourced “in good faith” from an Irish company.

“In the UK it’s costing £150m a year in herbicides to try and control it, never mind yield loss.

“If it’s coming from the UK, a huge amount are extremely resistant to the main herbicides we use. If you get it, there is no chance of controlling it in a arable context.”

He says huge amounts are imported “with almost no regulation”.

“A lot of imported wildflowers are not native to Ireland. We don’t know anything about purity or germination. They’re doing more harm because they’re flowering at the wrong time.

“They might look pretty but they’re not good for biodiversity. If schools or tidy towns plant them beside a tillage crop its potential as a contamination source is huge. If you want them, stick them in a pot outside your house.”

The affected Oak Park plot was since burnt and mowed, with ground cultivation to be monitored closely over the next three years.

No regulation

The Department of Agriculture said there are no EU regulations governing the importation and certification of wildflowers.

“The Department does not receive details of wildflower imports from the trade. While the EU seed regulations cover certain weed and disease species, there are no specific controls relating to blackgrass.”​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​

“This also applies to third countries, including the UK, with which the EU has an equivalence agreement for trade in certified seed for the main agricultural crops.”

The Department has an agreement with the Irish Seed Trade Association to impose “a zero tolerance” for blackgrass, wild oats and brome in certified seed grown in Ireland and is engaging with the industry presently.