Make the best of opportunities to get an early start on weed control in Spring Cereals

April 24, 2020

Robin Bolton and Leigh McClean CAFRE Crops Team

Good weather and favorable ground conditions from late March has allowed good progress with spring cereal sowing. Crops sown into warm soil, combined with sufficient moisture should see crops germinate quickly. Achieving good weed control should then be the next focus. With resistance to certain broadleaved weed herbicides widespread e.g. Chickweed resistance to ALS inhibitors (Sulphonylureas) the opportunity to use different modes of action in pre- emergent herbicides should not be missed.

Pre and early post emergent herbicides generally bring two benefits to spring cereal weed control. Firstly they help combat the buildup of resistance through introducing different modes of action on broadleaved weeds. Secondly they provide the best opportunity to control annual meadow grass in spring cereals. To get the best results from these products it is best to apply them to damp, firm seed beds and performance is best when used pre-emergence of the weed. Good application is important when applying pre –emergent herbicides. Angled nozzles can help to ensure good coverage of the soil surface, including any clods, and when spraying keep booms low (ideally 50cm from target) and work at slower forward speeds (below 12KPH).

It is important to ensure you comply with all the regulatory conditions when spraying and this especially important when applying pre-emergent herbicides to spring crops. Very few products have full label approval for use pre-emergent on spring barley with Liberator being an example of one that does. Other products e.g. Crystal can be applied under an Extension of Authorisation for Minor Use (EAMU). If applying under these conditions you should have a copy of the EAMU available and comply with any conditions on it which may be different from those on the product label.

Some labels also differ for early post emergent use for example Liberator can only be used post emergent under an EAMU but as already mentioned has full label approval for pre-emergent use. Your Basis agronomist should be able to provide the necessary detail to keep you within the law. Pre-emergent herbicides are available for other spring sown cereals but again many will be under EAMU and they will vary between products so it is always worth checking that the product is recommended for the crop you are using it on. Note of caution any product applied under an EAMU is done so entirely at the growers risk.

For more information on herbicide resistance see herbicide resistance action committee (HRAC) website http://www.hracglobal.com/Home.aspx

For the most up to date information on approved products and extension of authorisation for minor use see the HSE pesticide register search page
www.pesticides.gov.uk/pestreg/prodsearch.asp