There are no simple answers to the problem of black-grass, according to Frontier Agriculture’s head of innovation and knowledge exchange David Robinson. Any approach to the problem must be multi-faceted and designed for the particular conditions on-farm.
David Robinson says some growers may be tempted to ‘rest on their laurels’ following a good performance by residual herbicides last autumn, but warns: “Residual herbicides definitely performed well in the autumn, but this result needs to be treated with caution, and we cannot rely on the conditions being the same going forward.”
Frontier has been exploring a wide variety of approaches and it believes success will depend on getting the combination that is right for your farm.
He says resistance to black-grass has become a problem across the UK due to a number of factors including increased winter cropping, earlier drilling, misidentification and consequent slow response to infestation, increasing resistance to actives, and physical movement of seed.
It is not just the direct problems black-grass brings either. Infestations can lead to an increased risk of ergot.
While achieving zero black-grass is an admirable target, it has little or no chance of success. However, Mr Robinson believes it is possible to prevent significant increases, or ensure consistent reductions year-on-year.
He says: “Chemical control can still be effective and there are new actives in development but it is a slow process. There is a new residual herbicide in trials at the moment, but in the meantime, the pressure on current actives is immense. I believe every field of barley or wheat will have seen flufenacet at some stage and this is putting a lot pressure on this active.
“Our trials show the rate of flufenacet application is increasing in order to sustain acceptable levels of efficacy. This is a clear indication that selection pressure is beginning to take its toll.”
Mr Robinson says when it comes to chemical control there are no half measures. To ensure any degree of control, full rates of application are required and a comprehensive programme which starts at pre-emergence and goes all the way beyond post-emergence. Stopping at any point in the process risks a rapid increase in black-grass seeds. The days when control through herbicides alone could be achieved are past and Frontier is exploring a number of other strategies.
For instance, the company has demonstrated the use of certain water conditioners has improved the efficacy of contact herbicides, particularly in hard water areas. For example, Aquascope, which improves the performance of clethodim applied to blackgrass in oilseed rape.
Frontier is also looking at other regimes which will help support the use of chemical controls. These include pre-drilling cultivations and the use of glyphosate, drilling dates, crop competition and rotational changes.
The company has been involved in trials with ADAS, AHDB and other industry partners looking at the use of glyphosate in stubble and pre-drilling cultivation which explored application at various stages of black-grass growth and different levels of application, as well as cultivating or not cultivating.
In this trial, two sequential applications of glyphosate at 1.5 l/ha (applying a total dose of 1,080g/ha active), achieved the best result. These applications were made as black-grass reached leaf stage 2.
When it comes to exploring how different rotations, methods of cultivations and timings of drilling can affect black-grass, Frontier has been able to do pioneering work on a site with high black-grass infestation at Staunton in the Vale. The trials there are part of the company’s ‘3D Thinking’ - its research and development programme which splits its regional sites into Discovery, Development and Demonstration sites.
At Staunton, trials have been ongoing since 2012, with 10 different regimes being used to assess their impact on black-grass numbers and yield.
Evidence to date shows some of the most effective strategies are spring cropping, use of fallow years when treatments can be applied, and late drilling – with the latest possible dates providing the best results.
Christine Lilly, Frontier’s national technical and research manager, says: “We realise these strategies might not suit everyone. Where farmers are on their own land, leaving it fallow is an option, but it won’t appeal to those on rented land.
“Equally on some soils drilling in November may be difficult, but it can bring real benefits, as can a move to spring cropping. While this will reduce yields, there is a quid pro quo in terms of a dramatic reduction in black-grass, and the possibility to return to winter crops in due course.”
Mr Robinson says those who do decide to move to spring cropping should not ‘jump the gun’ but wait until around the third week in March to drill.
For those concerned about whether they have resistance on-farm, Frontier has been doing work with Newcastle University on a test which could soon make it easier to get answers. The test, which measures non-target site resistance, is simple to do. Using just a few leaves, the ‘pregnancy’ type test produces an indicator of non-target site resistance within minutes.
Another piece of pioneering work is the research being carried out by Frontier into the use of a ‘chaff deck’ at harvesting to control the return of grass-weed seed.
Paul Fogg, crop production technical lead for Frontier, says concerns the technology, which has been developed in Australia, might not work in the UK have proved unfounded.
He says: “Initial results are very encouraging and we are really pleased the chaff deck demonstrated improved control of seed return. Perhaps even more significant is the chaff deck was not hindered by a single blockage during harvest. We knew chaff deck could work to control grass-weeds because of its extensive use in Australia, but there were question marks over its value under UK conditions, particularly in black-grass situations.
“Based on one year’s results there are now some positive indications its mainstream success in Australia could be replicated in the UK. Sustainable black-grass management requires a fully integrated approach. However, harvest weed seed management and the use of chaff decks for tramlining is one additional novel approach we may be able to add to our tool box.”
As a result of the success of the trial in 2017, Frontier has announced it will roll it out to more farms for trial in 2018.
Watch David Robinson talk more about the pioneering work being done on black-grass control in the video above (top right).