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Weeds in Winter cereals, May 2019

2 May 2019

Most winter cereal crops are now past the growth stage where annual meadow-grass can be adequately controlled. However, there are still opportunities to tidy up broad-leaved weeds such as cleavers, chickweed, mayweeds and others. ALS herbicides tend to have wide windows of application, often up to the flag leaf stage in wheat and barley.

Most wheat crops are at too advanced a growth stage to control annual meadow-grass.  There are some options available, and after seeking advice from your agricultural or agronomist adviser, remember that these should not be applied to crops under stress.

As crops move into later growth stages and grass weeds become visible above the crop, it is a good time to check that fields are clear of problem grass weeds. A black-grass infestation often starts with just one or two plants going unnoticed. Due to the low dormancy of seeds shed from these plants, the infestation develops rapidly. Now is the time to check fields, because by harvest time up to 90% of black-grass seeds may already have been shed. Plants need to be removed from the field as soon as they are seen in order to prevent any seed return. Prevention of seed return is the key to controlling grass weeds, particularly black-grass. Rogueing weeds such as black-grass and brome species are possible – they need to be pulled from near the soil level then the whole plant removed from the field.

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