Weed control authority, Dr Stephen Moss urges growers to assess the grassweed status of their fields each summer to review and adapt their management in a thorough integrated way every season.
“Black-grass is clearly becoming an issue for growers wherever they are in the country,” he insisted. “What’s more, you can virtually guarantee a degree of resistance in all populations.
Italian rye-grass is even more problematic than black-grass in some parts of the UK; brome is an increasing threat; wild-oats should never be ignored and couch remains widespread.
“Both increasing herbicide resistance and a decreasing chemical armoury are adding to the grassweed challenge. Gone are the days when you could reliably control these threats with herbicides alone. Instead, you need to take advantage of every cultural and chemical control opportunity you have in a thoroughly integrated, systematic way, field by field.
“We know that the key to annual grassweeds is to prevent seed return. Numerous on-farm studies show the black-grass seedbank can be reduced by 74% a year by doing this. If black-grass has one weakness, it’s the relatively short persistence of its seeds in the soil. We need to capitalise on this vulnerability. Theoretically, we should be able to decrease weed levels by as much as 99.9% over a five year period.
“Preventing seed return is easier said than done, though. It requires an understanding of the weeds involved, the discipline to keep up the pressure on them over several years and sufficient management flexibility to make the most of the full range of control tools available.”