Slender foxtail, Black twitch
Bluish-green, short, flat and hairless. Usually rough with a well-defined keel and usually rolled.
Tall, erect annual. Compact flower spike 3 - 13 cm; narrow and pointed, often tinted purple. Seedling leaf sheath often purple.
About 80% of shed black-grass seed germinates in the autumn and consequently it is mainly a problem in winter crops. Under wet and saturated conditions, dormancy can remain unbroken until the spring when further germinations affect early sown spring crops.
The bulk of black-grass seed only survives in the soil for two years, serious infestations generally being associated with intensive winter cropping – winter wheat and barley and winter beans.
Increasingly a major problem throughout England and worsening through herbicide resistance. Yields of winter cereals can be reduced by 1,260 kg/ha. Black-grass can carry over the take-all fungus (Gaeumannomyces graminis), further exacerbating the impact on yield and nullifying the beneficial effects of a rotation in containing the disease.
Controlling black-grass is a year-round task, requiring cultural and chemical controls.
June and July are the best times to check black-grass populations and plan your control programme.
Black-grass plants are visible above the crop canopy, so you can take the time to note black-grass hotspots and count the number of plants per square metre. This, combined with testing seed for herbicide resistance gives you an idea of the extent of the black-grass problem and how to tackle it.
Immediate steps include patch spraying, hand-rogueing and harvest weed seed management. Looking further ahead, there is the opportunity to plan crop rotation, cultivation and establishment for the coming season.
For a more detailed blueprint on how to manage black-grass, read our detailed guide, Black-grass: The definitive Resource