BLACKGRASS REPORT - (Alopecurus Myosuroides) THE BATTLE THAT IS BLACKGRASS

Introducing Agri-Linc’s official 2018 report on the best way to deal with the nemesis weed of every arable farmer, compiled from several months of research, collecting information from our own insights, the industry itself, and our customers themselves.  Though this report should be helpful for the future, we have also worked to make sure that what is written here can particularly help you respond to an extraordinary growing season, which only calls for extraordinary measures.

INTRODUCTION:

Overall, it’s clear that there is no total panacea that can be credited for the eradication of this weed.  This report promises no cure but suggests practices that will best control blackgrass where possible.  We have found that what works best is a holistic approach, that is swift to change and adapt.  It is also key to remember that no two farms are the same, so the same combination of cultural and chemical approaches will not work for everyone.

Dick Neale, in an Anglia Farmer article published in August 2018, said that this season ‘phenomenal patience’ is required in beating blackgrass.  According to Agronomist & Arable Farmer, 2018 is ‘showing itself to be the worst year for black-grass seed return since 2012’, thanks to an exceptionally early harvest. One single approach will not work - Ben Coombs of Bayer has said in a recent FWI online article that ‘blackgrass control needs to be about adding together different elements for marginal gains to get to the point where you are successful’. Rather than settling for zero-tolerance of blackgrass, it is probably more reasonable to say that blackgrass is a part of every arable farmers life. While perfection may seem unattainable, we have some advice that may get you close to the mark.

WHAT IS IT?

Black grass is a native weed found particularly on heavy soils with poor drainage – the weed is only found occasionally on other soil types, but evidence of the weed has begun to appear in chalk soils. About 80% of blackgrass seeds germinate between August and October, and in a hot and dry summer such as this one has largely been, germination will occur earlier. Blackgrass is proven to significantly reduce overall yield, and cause grain contamination in cereals.

WHY HAS THERE BEEN A GROWING ACCUMULATION OF IT IN THE UK IN RECENT YEARS?

Firstly, the majority of blackgrass now emerges amongst a crop, rather than before drilling (as before), which means that it is harder to destroy.  What’s more, herbicides now offer no real means of control, since herbicide-resistant strains of blackgrass now occur on virtually all farms.  Many herbicides are seen as harmful for the environment, so risk being withdrawn (if they haven’t been already) from the farmer’s armoury against the weed.  As farmers have become more desperate to tackle the problem, they have relied more heavily on herbicide control, which has only served to increase herbicide-resistance.

OUR INSIGHTS

In the time since 1924, when our business first began, we have developed products that are aimed at minimising the effects blackgrass can have on yield, and we have met many farmers who are well-acquainted with the problem.  It’s not unusual for one of our customers, before receiving one of our machines on demo, to ask where the machine has come from, as they fear the dispersal of blackgrass seed from field-to-field via the machine.  To any of you readers who aren’t familiar with the scale of the problem, that may seem bizarre, but Bayer has denounced blackgrass as the ‘biggest agronomic challenge facing most UK arable farmers’, since it has been estimated that even 12 plants per metre-squared can reduce yield by 5%.  Maybe then, such a request from one of our customers seems reasonable.

POSSIBLE SOLUTIONS:

TO PLOUGH OR NOT TO PLOUGH?

Use of the plough is debatable – though it is advised every four to five years, if used every year or thereabouts, growers will struggle with blackgrass problems, because they are resetting their soil structure each year, and bringing to the surface buried blackgrass seed from previous years.  However, a report published by ADHB in 2014 suggested that ploughing on an irregular, occasional basis offered farmers 69% blackgrass control, by burying freshly shed seeds so far from the surface that they were unlikely to emerge – that being a depth lower than 5 cm.  Ploughing essentially acts like a reset button in terms of blackgrass, and should be used as a rotational tool, as opposed to a yearly institution.

One school of thought would be to leave stubble uncultivated and operate a min-till/no-till strategy which would allow the seed to be exposed and to germinate.  With the dry 2018 harvest, shallow tillage seems to be the preferred option.  Intensive Cultivations may bury seed underneath the surface, which could increase the seeds dormancy, which means that the seed may recur a couple of seasons later when the soil is disturbed, damaging a crop.  Extended dormancy makes the ‘dormant’ population very unpredictable for a farmer to manage.  However, failure to control black grass using minimal inversion methods could result in seriously damaging and rapid blackgrass infestations, against which heavy inversion like ploughing would be a preferred option.  Overall, it’s clear that the general feeling is to turn to ploughing once blackgrass infestation has gone past a manageable level.

This year, blackgrass dormancy has been hailed as very low, so perhaps minimum-tillage is the best option, which could mean that blackgrass control will be easier to achieve, because the grass-weed is likely to emerge quickly, which would enable its removal before drilling.

CROP-ROTATION & SPRING CROPPING

Autumn-sown cropping is lauded by many schools of thought as the blameworthy reason for increasing black grass, besides ensuing other problems like pests such as flea beetle, (see my blog : https://www.agri-linc.com/blog/flea-beetle/) which farmers have struggled to combat this year.  Spring-sown crops have consistently good reduction in weed infestation compared to autumn-sown crops.  However, spring-crop establishment is more of a challenge compared to the choice of autumnal-sowing.  In recent years, spring crops have tended to outperform some blackgrass infested wheats, as spring drilling breaks weed patterns effectively.  Either way if one thing’s clear, it’s that weeds favour predictable rotation patterns, and patterns of that nature will only increase herbicide resistance.

BENEFITS OF MOLEDRAINING

Typically, cloddy and heavy land associated with poor drainage is also associated with poor blackgrass control.   Poor drainage can be easily remedied with the use of a combatant mole-drainer such as those PROFORGE stock. See PROFORGE’s best-selling mole-drainer here : https://www.agri-linc.com/proforge-monomole-mounted-beam-mole-plough-new.html .

HAND ROGUEING IN THE SUBSEQUENT JUNE

This is admittedly rather a cumbersome task, and is probably only feasible in areas of low-weed population.  The timing of hand-rogueing is critical – you won’t want to be returning to fields before harvest to pick out plants that have grown in the time between first-rogueing and harvest.  On the other hand, left too late, the plant will disperse their seeds, which can cause extensive damage.

DELAYED DRILLING

Delayed drilling is favoured by many farmers as being a suitable choice for blackgrass control, but it should be delayed no later than the end of October, otherwise crop establishment may be hampered.  Research also shows that pre-emergence herbicides are more effective when applied in later-drilled crops.  Blackgrass also tends to produce fewer seeds and be less competitive when emerging in later-drilled crops.  Early drilling of winter cereals will lead to mass infestations, as it coincides with peak blackgrass emergence, so the best option is to delay drilling, and eradicate a flush of blackgrass emergence beforehand.  However, we realize that this year, farmers are keen to drill earlier, because of the unusually early harvest.

HERBICIDE USAGE

It’s sound advice to spray off any particularly bad areas of blackgrass infestation with correct doses of glyphosate, and make sure powerful pre-emergence and post-emergence programmes are applied, both including residual elements.  Mix and vary herbicide treatments, to avoid high levels of resistance, and always use full dosages.  It is hoped that recent rain will have a positive impact on the effect of herbicides, but as a general point, growers are advised that good seedbed preparation is key to getting successful herbicide results.

NEW HERBICIDES COMING TO THE MARKET?

Agrochemical company Bayer will launch a new pre-emergence herbicide in 2019, that promises 10% improved control of blackgrass in winter wheat, compared to their current highest-performing chemical weed-killer, Liberator (which is currently only minorly effected by herbicide resistance).  The addition of metribuzin to the mix (a third residual element) is what will set the new pre-emergence herbicide apart.  Any weeds not killed by pre-emergence herbicides should be targeted by rogueing or post-emergence herbicides prior to harvest.

EXPERTS IN THE FIELD

While preparing our report, we came into contact with Mark Tucker at agrochemical company YARA, who told us that currently, bad blackgrass infestations are resulting in a yield penalty equivalent of up to ‘2 tonnes per hectare’.  He feels that ‘early winter sown’ crops are worst off from blackgrass damage, and YARA’s recommended solutions were ‘delayed drilling and spring cropping.’

CONCLUSION

We hope that one of these solutions can work for you and your farm.  As we’ve already said, it’s clear that patience is paramount, particularly this season. Please let us know how you are tackling blackgrass on your farm, we’re always glad to hear from you.

We would like to say a special thanks to Mark Tucker of Yara UK Ltd for his contribution to this article, you can check out Yara’s blogpost on blackgrass here.  Also we would like to thank Cameron Holmes, James Hopley and Alistair for their contributions to this article.