Black grass and other weeds in crop fields


New Member
Hello! To being with, I am not a farmer nor a biologist, but I am a researcher who works with plants and I need your help.

I know that BG (not to mention other weeds) is a big problem for UK farmers and we are all looking for solutions. I was wondering if you could let me know in which crop fields BG is the most common and has the biggest issues (e.g. winter wheat). In addition, I would be grateful if you could let me know what other common weeds are commonly encountered in these fields besides BG.

Any information is appreciated.


New Member
Blackgrass is worst in winter wheat.

Other weeds suited to the same land type as blackgrass would be cranesbill & cleavers. Lesser weeds in similar soils are charlock, redshank and black bindweed. Lesser grass weeds would be wild oats and sterile / great brome. Those who have grass in their crop rotation might consider ryegrass a problem weed.


Blackgrass is a major problem in winter cereals, because both the crop and weed are grass species, therefore herbicides have to be more selective to control the weed. For controlling broad-leaved weeds in cereals, there is much more chemistry and control is generally much easier. Blackgrass is a problem mainly in UK, northern France and Germany. In the rest of Europe Apera species are the main grassweed (mainly central and eastern Europe), or ryegrass (mainly southern Europe).
In spring cereals, grassweeds are less of a problem, because often grassweed is allowed to germinate and grow over winter, to then be controlled by non selective herbicides before drilling in the spring. With winter cereals there is a much shorter time between harvest of the previous crop and drilling of the winter cereal crops, so there is less time for this to occur.
Of the winter cereals, wheat is the largest crop grown (both in terms of area and output), therefore blackgrass is the greatest problem in this crop.

The problem with blackgrass in the UK, is that there is a major resistance issue. Traditionally 'fop' and 'dim' chemistry have been used to control blackgrass, but over time most populations have become resistant to this chemistry. About 20 years ago SU chemistry (such as Atlantis) was launched; this was very effective and a lot of people used it (particularly since 'fops' and 'dims' very much less effective. Unfortunately, this reliance on one product and the modes of action is used, meant that resistance has now developed to this chemistry.

Currently, there is no major new chemistry in the pipeline, so people with resistant populations are having to use other products which alone do not give adequate control, but mixed together or in sequence are the best alternative. At the same time in cereal crops other non chemical methods and non selective herbicides between cereal crops are also being used. In non-grass species crops, there are is other chemistry available, but this is not completely relevant if you are interested in control in cereal crops.

Ultimately, blackgrass is a difficult weed to control, and chemical options alone are not enough, and so an IPM approach of both chemical and cultural methods must be used.

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