Agri-Food and Biosciences' Institute (AFBI) plant scientists are becoming increasingly concerned about the growing threat posed by Black Grass and Brome Grass infestations to Northern Ireland’s tillage sector.
Both constitute serious problem weeds in England with cereal crop losses of up to 75% being common in areas where it has become established.
According to an AFBI spokesperson, Black Grass reduces crop yields through competition for nutrients, especially nitrogen, adding: “Herbicide-resistant Black Grass has been confirmed in 34 counties in England and has also been detected in Scotland.
In the last couple of years there have been instances of Black Grass reported in crops in Northern Ireland. And it is well established in some areas.
“The most effective methods of control are cultural. These include delayed drilling, higher seeding rates, sowing competitive varieties, spring cropping and fallowing.
“However, there is unease amongst growers, seed merchants and the Ulster Farmers' Union that seeds of Black Grass could come into Northern Ireland on straw from the rest of the UK and Ireland.
Whilst Black Grass already poses a threat, AFBI scientists believe that Brome grasses have become increasingly common as a weed challenge within Northern Ireland’s cereal crops.
There are five species of Brome Grass found in Northern Ireland and as different control measures apply to different species, identification is important.
The AFBI spokesperson said that all species can reduce yield and quality with a density of only three plants per square metre causing yield losses of 2%, or more, in winter wheat.
“Yield reduction from plant competition is the greatest impact but high populations will also cause lodging.
“Un-shed seed will contaminate the combine and baled straw, thereby spreading the problem across the farm and onto other farms.
“Growers at higher risk of a problem developing are those sowing exclusively winter crops and not ploughing.”