Farm Ireland

Sunday 25 February 2018

New study aims to curb the threat of blackgrass weed

Darragh McCullough

Darragh McCullough

A new study to tackle Ireland's most problematic weeds is to commence this autumn.

Teagasc, along with the Irish Seed Trade Association, is funding research into the four most difficult weeds for cereal farmers: sterile brome, blackgrass, canary grass, and the ubiquitous wild oat.

"I've seen crops being wiped out by these types of weeds, and the shame about it is that it can all be avoided if the farmer reacts early enough," said Teagasc tillage specialist, Tim O'Donovan.

Weeds such as blackgrass are a potential nightmare for farmers because they are resistant to almost every type of herbicide that cereal growers routinely rely on.

"I wouldn't go as far as describing them as super-weeds because they can be controlled but it's a problem that farmers can do without," said Mr O'Donovan.

"Blackgrass is resistant to everything except glyphosate, and so it has got to the stage where it has wiped out crops in the UK.

"It's actually been found in pockets of northeast Leinster for many years, but farmers would still need to be very vigilant about introducing it to their farms.

"One of the biggest risks is the importation of straw, seed or machinery from the UK.

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"If farmers are careful to intervene now before it gets out of control, they can save themselves a lot of money," said the Teagasc man.

Wild oats

While both blackgrass and wild oats are at static levels, Teagasc's tillage unit has noted the spread of canary grass and sterile brome to more farms around the country.

"That's part of the reason behind this project. We've no information on the resistance status of weeds like this.

"The solution for most farmers is to mix up their cultural methods for a few years, by switching from min-till to a deep plough every three years, or switching from winter cereals to a spring crop.

"But this may not suit everyone, especially if a guy is set-up for min-till only," said Mr O'Donovan.

UK growers report increasing severity of blackgrass infestation, with a massive 30,000ha of cereals lost last year due to the weed.

One in five growers report spending over €120/ha for its control. In winter wheat yield losses of 63pc can occur where just 50 heads/m2 are present, according to UK agronomist, Sarah Cook.

She presented a paper on blackgrass control at Teagasc's tillage conference in Kilkenny last week.

The event drew a large attendance, and heard papers on winter wheat, beans, rotations, and the benefits of discussion groups for tillage farmers.

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