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Black-grass can greatly affect yield and cause contamination issues at harvest.  A few weeds one year can become a significant weed burden over a short time frame. While most seeds germinate in the autumn, you only need 12 plants/m2 to lose 5% of yield and resistance is a major problem in black-grass problem areas of the UK.  The best black-grass control strategies should follow an integrated approach, considering cultural control options, herbicide strategy and application technique.

What can I do?

• Consider resistance testing if you are unsure of the status

• Map where you predict grass weed seeds are, based on 5 year cultivations. Try our Culitavtion Insight Tool

• Monitor weather at weed flowering and assess dormancy

• Adapt your cultivation strategy accordingly

• Consider the implications of drilling date, cultivation strategy and soil type on grass weed emergence

• Adapt your herbicide strategy accordingly

• As a guide, aim to apply a pre-em within 48 hours of drilling. Apply a sequence 3 weeks later. Adequate soil moisture is important for good performance of residual chemistry

Cultural controls

Our Barton Black-Grass Innovation Centre, in its fifth year now, has shown that establishment method impacts herbicide strategy.  It’s important to consider where your black-grass seed is in the soil profile, what your resistance status is and what the dormancy level is.  This will help to make informed cultivation decisions and give you the best start of achieving control while managing costs.

Use our Cultivation Insight Tool to help visualise your black-grass seed in your soil profile based on your cultivations.

The best cultivation for black-grass control depends on the seasonal weather and how dormant your black-grass seed is. 

Trials have shown that direct drilling in years where seed is less dormant and germination happens over a short time frame can make black-grass easier to control as it is left on the surface where a robust pre-emergence treatment can be effective. Otherwise, continual germination of high dormancy seed is difficult to control with pre-emergence herbicides.

While min-till offers good seed-to-soil contact, it makes black-grass control more challenging because the soil profile and seed bank is more mixed.

A rotational plough is a good way of burying the weed seed down below the germination zone. This can be especially useful if seed is known to be high dormancy and therefore harder to control or following a significant seed return to establish a ‘re-set’. Effective ploughing should bury almost all seed but ploughing too often can return previously buried seed which is still viable to the surface. 

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Competitive cropping

Spring crops are a great alternative for the management of grass weeds.  Spring barley is more competitive than most spring wheats.

A spring crop needs to be competitive for good weed management.  If you don’t establish a competitive spring crop, you’re possibly losing all you have gained in the extra stale seedbed by allowing too much ryegrass or black-grass to thrive in the crop and return more seed.

 

Herbicide strategy

DEFY is a key part of your black-grass control strategy and is an essential pre-emergence herbicide partner product for both winter and spring cereal crops.  It has proven pre-emergence crop safety in winter wheat, with trials showing no phytotoxicity even at double rate, allowing you to add to your black-grass control.   While we know the aim is always to go on with a pre-emergence herbicide, sometimes conditions don’t allow this.  If this happens, you can adapt rates of Defy to suit your peri-emergence and post-emergence programme.  As a guide, aim to apply a pre-em within 48 hours of drilling. Apply a sequence 3 weeks later. Adequate soil moisture is important for good performance of residual chemistry.

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Dormancy

Seed dormancy describes when a grass weed seed will not germinate even when all of the necessary conditions for germination are met. Dormancy is not fully understood and we are working to learn more about how it impacts control strategies.  What we know so far is that weather conditions during maturation influence the dormancy of black-grass: a hot, dry year results in low dormancy in freshly shed seed, whereas a cool, wet year triggers a higher level of dormancy.

Watch the video and listen to our dormancy soundbite to find out more about grass weed seed dormancy.

Application

Application is more than getting your chosen product onto the crop.  We research and trial application techniques to give you the best advice on how to do this as sustainably as possible, considering weather conditions and the environment to help you get the most out of every drop.

That’s why we advocate to go low, go slow and get covered.  Boom height, forward speed and water volume can all improve your application practice, especially with a drift reducing nozzle in certain situations.

Application can contribute up to 50% of your chemical control so every little improvement in technology or technique can increase control.