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Black-grass

Key learns from Barton Black-grass Innovation Centre

The key insights from Barton come from overlaying weed control tactics over multiple years, and monitoring both weed control and margins. The site is now in its fourth year and we have begun to establish some interesting principles.

Know what you're up against

1. Population

2. Resistance

3. Dormancy

Know what you're up against

1. Population

2. Resistance

3. Dormancy

Dormancy

Seed dormancy is the term used to descirbe when a grass weed seed will not germinate even when all of the necessary conditions for germination are met. 

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.

At Barton, dormancy tests have shown high dormancy in all seasons except 2018/19, following the hot summer of 2018.

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

Cultivation matrix - establishment

At Barton, in our matrix field, we have crossed both cultivation technique and crop species to look at the effect of population, resistance and dormancy across the rotation. The work will continue for 5 years to enable to effects of the rotation to become evident, for both grass weed control but also margin over input costs across the rotation.

Three year cultivation strategy findings

Our findings suggest that using the same cultivation year on year isn’t the way to achieve the best margin or black-grass control. We found:

Best margin: DD/Min-till/DD

Best control: DD/Plough/DD

Worst margin: Plough/DD/DD

Worst control: Continuous min-till

Three year cultivation strategy findings

Our findings suggest that using the same cultivation year on year isn’t the way to achieve the best margin or black-grass control. We found:

Best margin: DD/Min-till/DD

Best control: DD/Plough/DD

Worst margin: Plough/DD/DD

Worst control: Continuous min-till

Cultivation & black-grass control

This table shows the effect of each cultivation on black-grass control in each season.

Cultivation & margin

This table shows the effect of each cultivation on margin in each season.

How seasonal context affects margin & control

As you can see the cultivation strategy that has given the best ‘control’ (or reduction) in black-grass over the 3 year period is DD/Plough/DD. This is despite the Plough giving the best control on average in both years one and two when considered as individual seasons. Best control was seen in a situation where the previous year’s plough offered a ‘re-set’ before direct drilling, meaning there was only one season’s seed return to contend with. Due to the low dormancy of that freshly shed seed residual herbicides worked well where that seed was on the surface in the direct drilling. The position of the plough in the multi-year strategy is something we are interested to understand further as the project progresses.

The best margin came from a DD/Min-till/DD strategy where there was a balance of moisture retention in undisturbed soils in dry summers and good establishment in the wet autumn of 2017.

Black-grass herbicide strategy

Cultivation method, drill date and soil type all have an impact on when black-grass seeds will germinate. This has implications for your stacking versus sequencing approach and timing of herbicide application.

Where black-grass emerges from affects herbicide performance

Our data shows that where black-grass emerges from (due to cultivation) affects herbicide performance. In autumn 2018, leaving seed on or very close to the surface helped with pre-em control. In this low dormancy year, black-grass seed germinated quickly and the large stack was the best option in a direct drilled situation. Where weeds emerged from deeper, they emerged over time and the sequence showed an advantage over the large stack.

However, in the high dormancy year of 2016, seed on the surface germinated over a longer period of time, and there was an advantage to sequencing herbicides, even in the direct drill situation.

Where black-grass emerges from affects herbicide performance

Our data shows that where black-grass emerges from (due to cultivation) affects herbicide performance. In autumn 2018, leaving seed on or very close to the surface helped with pre-em control. In this low dormancy year, black-grass seed germinated quickly and the large stack was the best option in a direct drilled situation. Where weeds emerged from deeper, they emerged over time and the sequence showed an advantage over the large stack.

However, in the high dormancy year of 2016, seed on the surface germinated over a longer period of time, and there was an advantage to sequencing herbicides, even in the direct drill situation.

A spring crop needs to be competitive for good black-grass management

In the crop rotation matrix poor establishment of spring barley due to the dry 2019 spring gave poor yield, return and the worst black-grass levels.

If you don’t establish a competitive spring crop, you’re possibly losing all you have gained in the extra stale seed bed by allowing too much black-grass to thrive in the crop and return more seed.

A spring crop needs to be competitive for good black-grass management

In the crop rotation matrix poor establishment of spring barley due to the dry 2019 spring gave poor yield, return and the worst black-grass levels.

If you don’t establish a competitive spring crop, you’re possibly losing all you have gained in the extra stale seed bed by allowing too much black-grass to thrive in the crop and return more seed.

Actions

1. Map where you predict grass weed seeds are based on previous cultivation strategies.

2. Monitor weather at weed flowering to help understand dormancy for the coming season.

3. Adapt your herbicide strategy accordingly, using stacks or sequences for best control.

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

5. Start spring cropping in the autumn by preparing seed beds to achieve good crop establishment.

More about Barton

Find out more from Barton Black-grass Innovation Centre

Pre-em application

Find out how to get the most out of your pre-emergence application