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In this issue...
Blending success page 31 Talking tillage page 48
Is growing wheat blends worth the hype? Highlights from this year’s Tillage-Live
Seed supply outlook page 72 A final word page 75
Opinion
4 Foreword - A word from the editor.
Volume 23 Number 11
6 Smith’s Soapbox - Views and opinions from an Essex peasant…..
October 2021 40 Nature Natters - A nature-friendly perspective from a Cambs farmer.
75 Last Word - A view from the field from CPM’s technical editor.
Technical
8 Grassweed control - Time after time
CPM takes a look at the lifetime of Avadex on its 60th birthday.
11 Grassweed control - Cost to pay if don’t delay
A look at the implications on grassweed control when drilling wheat early.
14 OSR herbicides - Changing perspective on blackgrass control
Trials indicate there’s scope to manage blackgrass differently in OSR.
18 Pushing performance - Hold on a bit longer
New research shows how adjuvants effect herbicide movement in soil.
22 Adjuvants survey - Understanding adjuvants
Survey reveals room for improvements when it comes to selecting adjuvants.
Acting Co-editors
Lucy de la Pasture Charlotte Cunningham 26 Maize trials - Trialling a route to better maize
Trials in Cumbria are shedding new light on maximising productivity.
Technical editor
Lucy de la Pasture 28 Real Results Pioneers - Soil focus eases blackgrass burden
Machinery editor Tom Sewell has a soil first approach but does this help or hinder blackgrass?
Charlotte Cunningham 31 Wheat blends - Blending success
Writers CPM finds out from growers what makes a good blend and why they choose
to grow them
Mike Abram Melanie Jenkins
Tom Allen-Stevens Rob Jones 34 Theory to Field - Vegetable GIN solutions
Lucy de la Pasture Plant breeders are finding GINs are providing answers to growing problems.
Charlotte Cunningham
Design and production
37 Forward-thinking farmers - An evidence-based approach
Alex Borthwick is trying to farm more efficiently for a sustainable future.
Brooks Design
Publisher
Steve Kendall Machinery
Commercial Director
Angus McKirdy 41 Tractors - Endless options
What are the choices available for something new?
To claim two crop protection BASIS points, send an email to
cpd@basis-reg.co.uk, quoting reference CP/112061/2122/g. 48 Tillage-Live - Talking tillage
Highlights form Tillage-Live as the event returned to its Gloucestershire home.
To claim two NRoSO CPD points, please send your name,
NRoSO member number, date of birth and postcode to 52 Forage harvesters - Go forth and forage
angus@cpm-magazine.co.uk A look at all the latest developments in forage harvesters.
*the claim ‘best read specialist arable journal’ is based
on independent reader research conducted by 56 On farm opinion - A place for the plough
Is there still a place for the plough in the arable rotation?
McCormack Media 2020
Editorial & advertising sales 60 Machinery Masterclass - Investment unlocks efficiency
A look at Grimme’s CleanLoader to see if it lives up to its reputation.
CPM Ltd, 1 Canonbury, Shrewsbury, Shropshire SY3 7AG
Tel: (01743) 369707 E-mail: angus@cpm-magazine.co.uk
Customer Service Innovation
Kelsey Media, The Granary, Downs Court,
Yalding Hill, Yalding, Kent ME18 6AL, UK 64 Digital direction - Another level of accuracy
A new tool within the Omina platform calculates the true cost of carbon on farm.
Reader registration hotline 01959 541444 67 Climate Change Champions - Soil saviours champion carbon call
Advertising copy A summary of all nine finalists to help you choose the 2021 Champion.
Brooks Design, 70 Sustainable farming - Investing in green
Tel: (01743) 244403 E-mail: fred@brooksdesign.co.uk
Understanding Environmental, Social and Governance pressure.
CPM Volume 23 No 11. Editorial, advertising and sales offices are at
CPM Ltd, 1 Canonbury, Shrewsbury, SY1 9NX England.
Tel: (01743) 369707. CPM is published eleven times a year by
CPM Ltd and is available free of charge to qualifying farmers Roots
and farm managers in the United Kingdom.
Copyright Kelsey Media 2021. All rights reserved. Kelsey Media is 72 Potato seed - Brexit impacts seed supplies
a trading name of Kelsey Publishing Ltd. Reproduction in whole or in A look at the implications of the ban on import and export of seed potatoes.
part is forbidden except with permission in writing from the publishers.
The views expressed in the magazine are not necessarily those of
the Editor or Publisher. Kelsey Publishing Ltd accepts no liability for
products and services offered by third parties.
crop production magazine october2021 3
CPM (Print) ISSN 2753-9040 CPM (Online) ISSN 2753-9059
able to do so is somewhat of a encourage you to do the same
luxury, but after 107 articles so this month. Originally hailing from
far this year across various titles I often meet farmers who tell Devon, Charlotte
–– equating to in the region of me the only day they’ve had Cunningham is now based
190,000 words –– as well as the off in their working life is their in Warwickshire and when
PR projects I work on on the side, wedding day. The prospect not busy filling the pages of
a rest seems warranted. (And seems criminal and leaves CPM, can be found in the
also the fact that I realised lately scope for so much to pass garden, or exploring the
that I can’t retire until 2062 before you without you ever countryside with two crazy
–– and if I even want to make it really realising. Food for spaniels in tow.
to that point, something has thought, hey? @charcunningham
to give!) In an industry where time off
Filling the pages of agricultural or away is still looked down
The winds of magazines largely mimics the upon, I truly believe a change
change blow farming calendar. Autumn comes of attitude is needed. We talk I apologise for not leaving
and combines are swapped out constantly of the troubles with you with something more
for cultivators and drills, then you recruiting and retaining staff, technical, but with columns
A gust of wind rushes past my blink and all of a sudden we’re but with a work-life balance often an insight into the inner
office window and as I peer talking about T1’s and shortly often scoffed, is it any wonder workings of a writer’s mind, this
out, I notice several big russet after, pre-harvest safety again. why some choose to settle for is mine this month.
leaves float delicately to the The nature of farming doesn’t a simple 9-5? A career in Change can be refreshing,
ground. allow for much of a break –– agriculture is one that can be and as the winds continue to
With September temperatures something that generations of incredibly rewarding, but those blow, I wanted to remind you
remaining largely above 20°C farmers and farming families in it have to be rewarded too. of just that.
and October getting off to a have come to accept. But does
similarly warm start, it’s quite that make it right?
hard to believe we’re already I think we often patch over Slowing down means no longer missing out on the little, but significant, parts
into the autumn –– albeit it difficult times. Like when you get of life – like spending time with my family, or walking the dogs in daylight.
doesn’t feel like it just yet. Life a good crop of oilseed rape after Pesky dogs in question Flex and Molly.
seems to be passing before my years of being beaten by the
very eyes. pesky beetle. For me, every time
The autumn brings more the load feels a little heavy, I visit
change to CPM, as the a wonderful farmer or business
magazine welcomes new and get an instant dopamine hit
consultant editor, Charles Abel, which reminds me of how much
and says a very sad goodbye I thrive on my job and the
to Lucy de la Pasture who has masterminds and inspirational
poured her heart, soul and figures it allows me to meet.
unmatched knowledge into the But slowing down and taking a
pages of CPM over the past six break means no longer missing
years –– which I know will be out on the little, but significant,
missed by readers. parts of life –– like spending time
I too will be reducing the with my family, or walking the
frequency of my byline in the dogs in daylight.
magazine, after making a COVID has forced life in
conscious decision to reduce general to change pace and
my workload in a bid to achieve direction, and I think for many
that work-life balance we all talk it’s an opportunity to rethink and
about. I appreciate that being reassess and so I wanted to
farming does feel as if there are the farm down to ‘black gold’.
less ‘known knowns’ than there Guy Smith grows 500ha of
But five miserly millimetres of
combinable crops on the north
once was. Somehow everything rain from mid-August to
east Essex coast, namely
feels a bit more risky when it mid-September put pay to that St. Osyth Marsh –– officially the
comes to cropping plans for on all but the kindest land. driest spot in the British Isles.
the forthcoming year. The At least I didn’t have to go Despite spurious claims from
annual blackgrass battle through the torture of playing others that their farms are
–– that’s now starting to roulette in the cabbage stem actually drier, he points out
feel like the thirty years war cotyledon casino. None the less, that his farm is in the Guinness
–– means second wheats Book of Records, whereas
Looking a gift crop sown in the autumn are at best
the dearth of drilled oilseed rape
others aren’t. End of.
plants on the farm, together with
in the mouth a gamble and at worst sheer the cost of the lost opportunity is @essexpeasant
recklessness. causing me to lose one or two
So a mediocre harvest, made It wasn’t that long ago that marbles. had four or five true leaves at the
profitable by high prices, is second winter wheats were an I’m now looking at the 40 equinox.
put to bed and the grinding established part of the rotation hectares of self-sown plants If I lose my nerve with this
progress towards harvest 2022 on this farm, but now they seem behind last year’s crop through current bout of bravado, at least
begins. In a world that seems like some sort of dangerous an increasingly warped lens. As I’m preparing the ground for a
less predictable, I suspect I’m indulgence. So that leaves us with I know to my own cost in the past, crop of wheat which would be
not the only one who seeks more break crops or more spring and as many have reminded me, my usual preference behind a
some comfort from the annual sowing. With the rapeseed price self-sown OSR crops seldom give crop of OSR. With forty acres of
pattern that is the turn of the so astronomically high that it’s decent yields. They seem to grow this self-sown free gift, I could
farming seasons. nearly matching the fertiliser OK into the spring but then go hedge my bets and leave half of
Having said that, arable price, our plan was to put 30% of downhill rapidly as they approach it with the other half ripped up.
harvest and various diseases At the very least it will give me
start to bite. That old adage that something to write about in
you reap what you sow takes a CPM. Watch this space…
new version in the sense that And I haven’t yet mentioned
you seldom get to reap what that this crop is so ‘on message’
sowed itself. when it comes to zero till and
But this year the question is –– carbon capture that it positively
if prices remain around the £450 makes the latest direct drill look
mark, then how bad would the as sinful as a plough.
yield of a self-sown second OSR
crop have to be before it became
If rapeseed prices remain around the
a mistake to keep it? I’m mindful
£450 mark, then how bad would the
we’ve got to the autumn without
yield of a self-sown second OSR crop
spending anything on it. That’s
have to be before it became a
£50 to £100/ha of saved
mistake to keep it?
cultivation, seed and spray cost
added to the margin before we’ve
started. So to my mind, even 2t/h
wouldn’t be a crop of regrets next
July. Indeed it could give me a
gross margin of around £300/ha,
depending on how miserly I
manage to get with the inputs.
So as I write I’m devising ways
to significantly reduce the plant
count, which is about 300%
too high by 200 plants/m2 ––
otherwise known as ‘thick as
cress’, not that I grow much cress
nowadays. Our first attempt to
uproot a couple of hundred
plants/m2 is putting the subsoiler
through the growing crop, which
6 crop production magazine october 2021
“ There can’t
be many examples of a
herbicide which has
stayed approved for
60 years.
”
Technical
Grassweed control Time after time
Though a number of crop
oat herbicide for cereals and sugar beet. It market, the launch of Avadex Factor marked
protection products have was a brand-new herbicide launched as a an end to a major formulation challenge,
come and gone from the liquid formulation, applied pre-emergence whereby growers could apply a liquid which
of crop and weeds. If there was a downside, didn’t require any additional input,” he notes.
market over the past it was that it required incorporating “It required the use of novel technology to
60 years, Avadex has immediately after application.” create a specialist encapsulated formulation
This challenge was addressed and so that the capsules released the product
remained a constant feature. Avadex BW 10G (10% triallate) –– a into the soil to mimic the behaviour of the
CPM takes a look at the microgranule formula –– was introduced granule formula.
to the market. “This marked a major “This allowed for a wider adoption of
lifetime of the product breakthrough as it solved the challenge Avadex, specifically by users who didn’t
and the ever-changing of having to incorporate the product,” have access to their own microgranule
explains Barrie. applicator or a contractor who had one.”
weed picture. Not only has the product itself evolved
Research and development over that time, but so has the usage,
By Charlotte Cunningham. The research and development of the continues Barrie. “In the 1960s, we saw
product continued through the 1970s and Avadex taking off –– which was really the era
1961 –– the year that saw the demise of 1980s, and in 1994 Avadex Excel 15G (15% of widescale herbicide adoption across the
the farthing as legal tender, Yuri Gagarin triallate) was launched. “This was a more board.
became the first man in space, and also concentrated, precision formulation which “But around the late 1970s, this dipped
the launch of the residual herbicide, reduced handling and logistic issues seen in
Avadex. the previous versions, he adds. “In fact, we
Launched first as a diallate, followed saw the application rate go down from
soon after as its triallate formulation it’s 22.5kg/ha with 10G down to 15kg/ha with
become known for, Avadex has arguably the new 15G –– which made a huge
been a staple product in the crop protection difference to both farmers and distributors.
armoury for many years, and its Even today, this remains our key product,
performance –– to date –– hasn’t faltered, applied through specialist applicators.”
says Barrie Hunt, UK and Ireland technical Ten years later, Gowan purchased Avadex
manager at Gowan. “There can’t be many from Monsanto. “At the time, Gowan’s focus
examples of a herbicide which has stayed was really on the opportunity presented by
approved for 60 years.” blackgrass but also the rise of integrated
Looking back on its history, 1954 marked weed management –– and the potential for
the discovery of the herbicidal properties of Avadex in that slot,” adds Barrie.
the ‘-allate’ thiocarbamate chemical family, Gowan continued the development of the
which soon expanded to include diallate and product and were finally able to crack those
triallate, explains Barrie. “In 1960, the first initial Avadex challenges –– launching
The launched of Avadex BW 10G was a major
Avadex UK trials were carried out by Boots Avadex Factor in 2016, a liquid formulation
breakthrough as it solved the challenge of having
on behalf of Monsanto. A year later in 1961, which didn’t need incorporating. “It wasn’t
to incorporate the product, explains Barrie Hunt.
Avadex launched in the UK as a new wild just a case of putting a new product out to
8 crop production magazine october 2021
back slightly following
the introduction of post-
emergence wild oat herbicides.
Understandably, at the time the
reality was why would growers
faff about trying to incorporate a
product when a simpler option
was available.”
However, the rise of wild oat
resistance and the spread of
blackgrass meant the popularity
of post-ems were short-lived, with In 1961 Avadex launched in the UK
many growers reverting back to as a new wild oat herbicide for
Avadex once again, explains cereals and sugar beet.
Barrie.
Avadex usage faced
challenge in the early 2000s, effective man standing ––
following the launch of flufenacet coinciding with a rise in
and Atlantis (mesosulfuron+ blackgrass resistance and a
iodosulfuron). “This suddenly put greater focus on integrated weed
control back in the hands of management, an area where
growers, giving them the ability the product slotted in perfectly,
to control blackgrass post-em, adds Barrie.
but also gave growers a different Fast forward to today, and
method of application –– which against all odds, Avadex is still
didn’t require a microgranule providing effective activity
applicator, or incorporation.” against wild oats in particular ––
What happened next needs with just two cases of resistance
no real explanation, leaving logged across the products’
products like Avadex the last entire lifespan. “This is despite
resistance noted in other modes
of actions and products. Namely
this includes ACCase-inhibitors
(A/1), ALS-inhibitors (B/2) and
antimicrotubule mitotic disrupters
–– across both winter wild oats
(Avena sterilis ssp. ludoviciana)
and spring or
Gowan purchased Avadex from common wild oats (Avena fatua).
Monsanto in 2004, with the aim of “One of the reasons triallate is
using the product as part of an relatively low risk is because it’s
integrated weed management a multi-site or multi-enzyme
strategy. herbicide active against a range
of very long chain fatty acid
▲
Avadex – how it works
Avadex’s mode of action is enzyme,” explains Barrie. “Like
inhibiting the synthesis of very long fungicide chemistry, this is valuable
chain fatty acids, e.g. fats and in resistance management.”
waxes. In terms of its site of action,
Specifically, triallate is believed triallate only enters the grassweed
to interfere with the activity of a through the coleoptile where it
range of lipid elongation enzymes. inhibits seedling development.
Because triallate acts against a “It usually kills the germinating
range of these enzymes, it’s seedling so that it never
considered to be a multi-site emergences through the soil,”
herbicide. he adds. “The important thing to
“This multi-site activity is in remember is that once the leaf
contrast to the majority of herbicide is up and out, it’s too late for
groups which target a single triallate.”
Grassweed control
controlling wild oats and managing
blackgrass –– as well as other bromes
and ryegrasses.
Common wild oats themselves have been
around for almost as long as agriculture,
however, the nature of the weed has evolved
over that time, explains NIAB’s John
Cussans. “Winter wild oats are much more
of a recent problem. The first UK reports of
species was in 1910.”
Fast forward to today and the UK has just
come out of a really terrible year for wild
oats, he adds. “Primarily what seems to be
happening in the field is that the A. fatua In a 2019 survey, 30% of all wild oat populations
type –– those really late emerging spring were found to contain the ‘ludo’ type, explains
oats –– are resurgent, along with difficult John Cussans.
Avadex is still providing effective activity against conditions which make control a challenge.
wild oats – with just two cases of resistance “When it’s cold and dry and you don’t more within diverse rotations with spring
logged across the products entire lifespan. have active growth from the weed, you’re in cropping.
this situation. You’ve got an application “That said, it’s an association and not a
elongation enzymes. Target-site resistance
▲
window on the basis of the weed size you requirement and as such, the ‘winter’ and
is highly unlikely as so many elongation want to hit –– but you don’t have weed ‘spring’ common names need to be
enzyme mutations would need to occur growth. So we’ve had an awful lot of control treated with caution. Spring wild oats can
in the target weeds to stop the product failure –– not because of resistance but due occur and thrive in winter cropping, and
working. However, like many pre-emergence to poor conditions and late germination.” winter wild oats can equally be found in
herbicides, the threat of enhanced But winter wild oats are becoming an spring crops.”
metabolism resistance is always a concern.” increasing issue too. “In a 2019 survey, 30% So the challenge is clear, but alongside
For wild oat control Avadex continues to of all wild oat populations were found to the use of something like Avadex –– what
prove its power. “Across 47 trials, Avadex contain the ludo type,” explains John. “In the else can growers do to manage the growing
15G has given a mean wild oat control of central band across England, it was in well weed burden?
92.7% across both spring and winter over 50% of the samples. “The key things here are no-till, fallow and
cereals,” explains Barrie. “Meanwhile, “Where it occurs, the winter wild oat is non-cropped periods,” explains John. “Then
Avadex Factor across 11 trials delivered reported to be more of a growing problem there’s biosecurity to consider –– particularly
average control of 84.5%.” than spring wild oats. It seems that winter around the spread of the winter type. Crop
Bringing focus to today’s challenges, wild oats are associated with winter cereals, competition also has a roll to play. These
Avadex remains an incredibly useful tool for but the common/spring wild oat is seen factors together form that essential
integrated weed management approach.”
Getting the most from Avadex. John explains that wild oats are one of the
few weed seeds that are actively predated
To maximise control with Avadex Excel 15G, by granivores, and data has shown that due
there are a few important practical measures to seed predation, germination and fungal
to consider, says Barrie. attack, huge reductions in viable seeds can
“Firstly, we always promote Avadex as part result from leaving wild oat seeds on the soil
of an integrated weed control programme,” surface. “Conversely, cultivation soon after
he notes. “From a practical point of view, it’s harvest will increase wild oats in following
essential to consolidate loose puffy seedbeds crops.
before drilling and to make sure drilling depth “As well as this, wild oat seeds can
is correct. Remember, for wheat this should emerge from much deeper than other
be 4cm.” weeds –– such as blackgrass –– so
It’s also vital to apply within 48hrs of drilling, to soils with more than 10% organic matter or effective cultivations to bury seeds need
he adds. “With regards to the applicator, be consolidating after application if seed depth is to be deep and ideally use inversion.”
sure to check the ‘pipe work’, deflector plates likely to be affected. In terms of biosecurity, although the
and calibration regularly. “Remember to also consider the weather majority of wild oat seed is shed pre-harvest,
“Specifically, keep the deflector plates clean –– if it’s too windy to spray, it’s too windy to combining is a major cause of seed
and at the right angle. As a side note, Avadex apply granules.” movement –– both within fields and
Excel 15G can be applied during the frost, light From a rotational point of view, it sounds potentially in field, he adds. “Studies have
snow or rain provided the deflector/spreader obvious, but Barrie stresses the importance of shown a greater than 142m spread of wild
plates can be cleaned.” not undersowing grass species –– or sowing oat seeds by a combine.
When it comes to what not to do, applying oats/grass –– within one year of applying “What’s more, any farm-saved seed also
pre-em to very cloddy seedbeds is top of the Avadex Excel 15G. “Remember, some cover needs to be free from wild oat seeds to
list, adds Barrie. “We also advise not applying crops include oats.” prevent this spread further.” ■
10 crop production magazine october 2021Cost to pay if “ When it
comes to drilling,
don’t delay? low disturbance
is key.
”
Technical
Grassweed control
establishment will have reduced seed return intention to sow early. Good seedbed
Delayed drilling is the by a factor of 10 compared with conditions will give the potential for better
backbone of grassweed autumn-established situations.” and more rapid establishment –– not only of
In contrast to 2019, many more wheat the crop but also for grassweeds.”
control programmes, with crops were in the ground last autumn but That could leave growers with a tricky
mid-October the ideal in residual herbicide input was severely grassweed problem to manage, with a
impacted due to a turn in the weather which higher dependency on herbicides, he says.
blackgrass situations. put the kybosh on application. “Drier seedbeds reduce the efficacy of
But with drills moving from residual herbicides, so the optimum
mid-September, where Significant seed return utilisation of the these must be given serious
“Herbicide treatment was applied consideration to counter the emergence
does that leave grassweed post-emergence at best, but in some cases periods of grassweeds this autumn.”
no treatment went on in the autumn at all. While blackgrass has been the number
control. CPM finds out. Where a herbicide was applied, sequences one enemy over the past 20 years, there’s
were rarely possible and this has lead to also a new kid on the block to consider and
By Lucy de la Pasture a significant return of blackgrass seed,” that’s perennial and Italian ryegrasses.
he says. “The fear is growers are so focused on
Cam suggests growers should start to blackgrass that they may be blindly walking
The hum of combines was an intermittent plan their grassweed management this into the hurricane that is ryegrass. Why the
sound during a mainly dull and dank autumn using a traffic light system to rank concern? Well, if you’ve had the pleasure of
August which delayed harvest progress for fields from green to red, with fields in the dealing with resistant ryegrass then you’re ▲
many. But a kinder September means a red zone requiring spring cropping to
significant area of early wheat drilling has re-establish control.
taken place in reaction to the impossible “Earlier sowing obviously has the
conditions experienced in autumn 2019 consequence of reduced germination time
and again in 2020, believes Hutchinsons’ for any treatment of weeds prior to autumn
regional technical manager Cam Murray. sowing. Where crops were cleared relatively
So how is this scenario likely to impact early, a reasonable degree of soil moisture
weed emergence, competitiveness and the may have encouraged some growers to
application of both cultural and chemical produce stale seedbeds immediately
control measures? post-combining in the hope of encouraging
“The consequence of two extremely wet significant germination during August and
establishment periods means that many early September.
were forced to abandon winter crop “However, it’s been clearly established
plantings and revert to spring options, the that the majority of blackgrass doesn’t
majority of which were sown in March or germinate until late September, with the first
early April. This resulted in a significant 10 days of October being the optimum The majority of blackgrass doesn’t germinate
reduction in grassweed seed return,” germination period, so we can expect the until late September, with the first 10 days of
says Cam. same scenario in 2021,” he comments. October being the optimum germination period,
“Even where blackgrass is present, the “Planting winter wheat likely commenced explains Cam Murray.
very fact that it was restricted to spring from mid-September where there was the
crop production magazine october 2021 11Grassweed control
with graminicides, can also be useful ––
providing there’s no ACCase resistance
present,” he advises.
Cultivations are another important
consideration. “In non-inversion systems,
grassweeds love this philosophy and
ryegrass will proliferate in this environment.
So, as in crop rotation, use a cultivation
rotation –– the plough still has a place in this
instance –– even if it’s every few years,”
he believes. September drilling means there’s less opportunity
Wrong footing a lower population of grassweeds
“When it comes to drilling, low to make use of glyphosate to produce a stale
emerging into a competitive wheat crop, coupled
disturbance is key. Just as with blackgrass, seedbed.
with a spread of herbicide applications could have
the more you move the soil, the more
advantages, says Dick Neale. liquid formulation, dry seedbeds are
ryegrass will germinate.”
Knowing whether herbicide resistance a serious hindrance to the efficacy of
already well versed in the battle.”
▲
is present, and what type, is important Avadex Factor. Like diflufenican, aclonifen is
Should you take a zero-tolerance knowledge that will underpin herbicide a predominantly a broadleaf weed killer, but
approach? Cam’s fairly emphatic that the programmes so testing is a must, says Cam. it’s synergistic to grassweed herbicides ––
answer is yes. “If you have the chance of “If you suspect ryegrass isn’t being offering in excess of 10% improvements in
stopping ryegrass problems early on then controlled, then get it tested. Half the battle control when partnered with flufenacet. But
make sure you do.” is knowing what you’re fighting in the first that improvement in efficacy can only be
One of the key elements for controlling place –– time spent on reconnaissance is utilised in damp and cooling seedbeds,”
grassweed species is crop rotation. “As with never wasted. says Cam.
blackgrass, spring crops –– and in particular “Prosulfocarb (Defy) at the full 5.0 l/ha
spring barley –– are very competitive. Pulse Last line of defence (4000g ai/ha) rate is highly effective ––
crops, where you can get at the grassweeds “Chemical controls are the last line of however, you have crop caveats at that
defence in an IPM strategy –– not that you rate. Triallate (Avadex) is a highly useful
want to rely on herbicides too much –– but addition, followed up by flufenacet. But with
plan to attack any plants when they’re flufenacet’s resistance issues becoming
small.” more pronounced, caution is needed and it’s
Mixing modes of action is another important to test and know your resistance
strategic move, suggests Cam. Aclonifen status.”
(Bandau), launched last autumn, has shown Increasing the elements of the pre-em
promising results on ryegrass in its first stack will have little impact in dry seedbeds,
real season of use on UK crops, he so spreading applications through late
highlights. September and October to maintain the
Triallate and aclonifen all have active dose as emergence occurs will be
pre-emergence approvals. “These are far more effective, he believes.
key products for successful control of Wrong footing a lower population of
Increasing the elements of the pre-em stack will blackgrass, ryegrass and bromes, so dry grassweeds emerging into a competitive
have little impact in dry seedbeds, so spreading seedbeds will see them compromised from wheat crop, coupled with a spread of
applications to maintain the active dose as the off. herbicide applications could have
emergence occurs may be more effective. “Avadex 15G is well known to be among advantages,” adds Dick Neale.
the most effective in drier seedbeds but as a “It’s likely to be no less effective than
12 crop production magazine october 2021Grassweed control
The early versus late debate
Bayer is expecting a large area of winter wheat range of weeds, including difficult populations of “It also has some contact activity against
to be sown this autumn, provided the weather blackgrass and ryegrass. Trials show improved smaller weeds. High workloads and large areas
holds, as the current buoyant wheat price ryegrass control (up to 37% in one trial) and an of wheat to drill may mean there’s some
encourages planting and forward selling of grain. average of 10% more total blackgrass control, additional germination just before drilling which
Like last year, there’s a debate around the he explains. aclonifen can help tidy up.
merits of drilling wheats early, says Tom “Adding aclonifen also helps prevent the “Trials in potato crops using a slightly lower
Chillcott, Bayer herbicide campaign manager. development of resistance to flufenacet, which rate of aclonifen have shown good control of
On the plus side it ensures a large wheat area has been the mainstay of many pre-em small germinated broadleaf weeds and annual
gets put into the ground but on the other hand, programmes for over a decade but there are meadow grass,” he comments.
delaying drilling helps with grassweed control, signs of resistance developing. It’s really “But I would stress that this is very much
septoria and BYDV. important that we work to protect and prolong ‘plan B’ –– ensuring there’s a completely clean
“There is no right answer but based entirely the efficacy of flufenacet, which is an effective seedbed before drilling is a better option. It’s
on long-term weed control, it’s best to delay. and easy to use active.” also important to note that aclonifen should
However, we know that all sorts of factors will Aclonifen itself has a couple of features that only be used before the crop emerges.”
push farmers to go earlier, in which case it’s may make it particularly important this season, There are other options for farmers looking
vital to squeeze every bit of control out of he adds. “It’s persistent, with a half-life of over for a pre-em with some contact activity, adds
pre-emergence herbicides.” 115 days, so it continues to control weeds into Tom. “Octavian Met and Alternator Met (both
This season Proclus (aclonifen) is widely winter. This may be particularly helpful in earlier metribuzin+ flufenacet+ diflufenican) provide
available to tank-mix with Liberator (flufenacet+ drilled crops which require longer protection some control of emerged weeds because of the
diflufenican) to provide better control of a wide against weeds. metribuzin component
sowing in early October –– with a crop then strong crop that does compete with The rules to beat grassweeds have not
finding itself emerging into the optimum blackgrass emerging later underneath it. changed, emphasises Dick. “But given that
period of grassweed emergence, with little Delay only a bit to early October, having some people will ignore the rules by drilling
chance of offering a robust competitive created stale seedbeds earlier, and the crop early, it’s important to understand the
defence. will emerge with the blackgrass and lack consequences for grassweed control and
“Drilled in September, you get a big competition to beat it.” how best to minimise the impact.” ■
crop production magazine october 2021 13“ The majority
of detections (65%)
were after 1 February
and 10% were over the
0.1ug/l limit.
”
Changing perspective on
OSR herbicides blackgrass control
Technical
Could blackgrass in oilseed
spite of industry stewardship commitments,” “The idea was to explore whether more
rape be managed differently she explains. reliance could be put on clethodim to help
to reduce the losses of “The abstraction monitoring data shows control blackgrass. This shift in strategy
a steadily increasing trend in propyzamide could enable growers to follow up later in the
propyzamide to water? Some levels at river abstractions over the past six season with a reduced rate of propyzamide,
work being conducted by years. The average detection moved from if required, particularly at low grassweed
0.22 ug/l (2015) to 0.43 ug/L (2020) and the populations or where there’s a high risk of
Stephen Moss on behalf of scale and number of peaks have increased leaching,” he says.
water companies seems to over this time, according to Water UK data. The thought of using an ACCase inhibitor
“Significant peaks, as occurred in 2017 herbicide to control blackgrass may make
suggest it’s possible. CPM and 2021, overwhelm available treatment some growers throw their hands up in horror
finds out more. capacity in the short-term and in the longer because of the target site resistance long
term pose a risk of contamination to associated with this group of chemistry. But
By Lucy de la Pasture reservoirs.” Stephen points out that clethodim is less
affected than other herbicides with the same
Significant detections MoA and resistance develops at a slower
As autumn gradually creeps towards The trouble with propyzamide is that it isn’t rate, so it can still be used to improve the
winter, oilseed rape growers will be just a problem that occurs in the window of overall control of blackgrass.
keeping a keen eye on the temperature use, which legally closes by 1 February “A worldwide research review considered
and ground conditions to catch the according to statutory label requirements. clethodim to be the lowest resistance risk
optimum window for propyzamide “Propyzamide detections at abstractions ACCase-inhibiting herbicide as it found only
application. The stalwart OSR herbicide between January and May 2020 showing a two of the 11 known target site mutations
takes the last curtain call before the significant level of detections occurring confer high resistance,” he says, adding that
spring, with a tricky spot in terms of beyond the commencement of the closed there is also no evidence that it’s affected by
timing. The soil temperature ideally needs period,” comments Rebecca. enhanced metabolic resistance.
to be 100C at a depth of 30cm, which “1123 detections were recorded between Stephen explains the project set out to get
typically occurs around 10 November 1 January and 30 April 2020 and, of these,
when field conditions can be more 161 (15%) were above the 0.1ug/l legal
difficult to travel. drinking water standard for an individual
But growers are being asked to consider pesticide. The majority of detections were
drinking water supplies when propyzamide after 1 February –– 729 (65%) –– of which
is applied because it’s one of the pesticides 10% were over the 0.1ug/l limit.”
of most concern to the water companies, Despite a significant fall in OSR area
explains Rebecca Carter of Anglian Water. over the past few years and stewardship
“When present in high amounts, measures already well established, the rising
propyzamide can overwhelm the water trend for propyzamide in water is a worry. In
treatment work processes. Although an effort to find a solution, Anglian Water and
propyzamide can be partially removed using Affinity Water have been looking at ways
conventional treatment processes, unlike growers could reduce their reliance on Levels of propyzamide in drinking water has not
metaldehyde, peaks in levels cause the herbicide for blackgrass control in field been improving in spite of stewardship measures,
operational problems and the issue has trials carried out by blackgrass expert, explains Rebecca Carter.
been getting worse rather than better, in Dr Stephen Moss.
14 crop production magazine october 2021Propyzamide trend 2014-2020
Source: Water UK, 2021
an idea of the levels of resistance carried out on a field-by-field
to clethodim in the field and how basis. The good news is that,
it varied. The results confirmed even where relatively high levels
that blackgrass resistance has of resistance were found, the
much less effect on the field efficacy of clethodim in the field
efficacy of clethodim than was still very good in the trials,”
cycloxydim. he says.
“There was a lot of variation in Once their resistance status
results between samples –– from was established, three OSR field
different farms and even fields on trials were carried out to test 14
the same farm –– which shows different herbicide treatments
that resistance testing should be and the resulting blackgrass
▲
How does propyzamide move?
Propyzamide is strongly adsorbed
in soil and not readily desorbed,
explains Corteva’s Edward Bardsley,
and adsorption increases as soil
organic carbon content increases.
“Because propyzamide isn’t readily
mobile in soil because of its low
water solubility and strong soil
binding, the majority of chemical
remains in the top 5cm soil.”
Even so, some is finding its way
into water through surface run-off
and subsurface field drainage.
“Heavy rainfall events can cause One of the pathways by which
run-off by soil erosion with propyzamide gets into water is by
increased risk where there is soil surface movement due to soil erosion
compaction. as seen in this field ‘catch pit’.
“Losses via field drainage is
probably more important where soil the biggest risk will be dependent
structure allows a direct route from on soil type, slope etc,” he explains.
the surface to the field drainage “The overland flow noted in
system. Where applications to Stephen Moss’s work has been
saturated ground are made and are seen by farmers and agronomists
followed by persistent rain, this anecdotally, for example one of the
keeps propyzamide in solution trial host farmers showed Stephen
and allows water containing where he had applied propyzamide
propyzamide to be drained off. But and it had run into his grass buffer
whether run-off or field drains pose strip,” adds Becky.OSR herbicides
“We found an average benefit
of 10% (range 6-14% across the
Sensitivity to clethodim
three sites) from using X-Change.
Interestingly this was regardless
of water hardness so it’s possible
that acidification of the spray
solution is more important in
increasing clethodim efficacy,”
suggests Stephen.
Propyzamide used alone was
applied at 500g/ha, 750g/ha and
850g/ha (full label rate). It also
Field trials indicate there may be an substantially reduced blackgrass
opportunity to reduce the rate of populations at both the Twyford
propyzamide without compromising and Loddington sites. The two
blackgrass control, when it follows Clethodim was applied to different blackgrass populations in petri dishes at
herbicides used in sequence
a clethodim application, says 1 ppm and the % reduction in blackgrass growth was assessed.
gave the most consistent control
Source: Stephen Moss, 2021
Stephen Moss. of blackgrass, but the trials
indicate there may be an Herbicide trial results
control was assessed. Each opportunity to reduce the rate
▲
treatment had four replicates in of propyzamide without
a randomised block design to compromising blackgrass
minimise the effects of in-field control, says Stephen.
variation. “There was no evidence that
“We found clethodim alone, the higher dose of propyzamide
applied in September/October, gave more benefit when used in
gave good control of blackgrass sequence with clethodim. The
(75-87%) at all sites.” lowest rate tested (500g/ha) gave
The trial also investigated how similarly good control as 850g/ha
much difference the additions of at both sites.”
a water condition (X-Change) But what about the duration
made to the efficacy of clethodim, from control propyzamide if the
which is generally considered to rate is reduced? Stephen doesn’t
be affected by hard water –– it’s believe this is an issue. Twyford blackgrass populations (Feb/April 2021) after different herbicide
common practice to recommend “Propyzamide is applied approaches in OSR.
clethodim together with a water during November/December Source: Stephen Moss, 2021
conditioning treatment. when the majority of blackgrass
Stewardship guidelines What does Corteva say?
Fields at high risk include those ● Use companion cropping CPM asked Corteva whether there “While recognising the vital role
that have underdrainage or slope ● Consider CS options for wider was trials information to support of research in this area, it’s
down to a watercourse. High-risk buffer strips to protect water reduced rate propyzamide. A Corteva important that findings are robust
fields may also include those that courses and where fields slope spokesperson said: “Kerb Flo 500 and backed up by numerous studies
have problem levels of blackgrass down to watercourses, buffer and AstroKerb are extremely carried out in different locations,
or other grassweeds that require strips of 12-24m wide should be important products for arable varying weather and across a range
a programme of herbicides to considered. Where fields include farmers with OSR in their rotation of soil types and conditions to
maintain control. long, steep slopes, consider who have to manage grassweeds meet regulatory standards.
● Minimise soil and water establishing fallow strips along –– especially blackgrass –– and “Growers already have flexibility
movement by drilling across the the contours to reduce downhill broadleaf weeds to protect yields. on the label, which allows them to
slope or not putting in tramlines flow “Label recommendations, including modify the rates of propyzamide
● Use low ground pressure tyres ● Check if you are in a water the maximum use rates and applied appropriate to the
● Lift tramlines to reduce safeguard zone by going to maximum number of applications on grassweed population, species and
compaction MAGIC maps. If you are, then labels, for applying all crop protection resistance status. All growers,
● Avoid high risk fields e.g. sloping speak to your local water products are achieved from a robust advisors and manufacturers have
fields with watercourses company to see if they have any regulatory procedure and years of a responsibility to promote and
● Consider infield grass buffer locally specific advice relating to trials work under a wide range of use crop protection products
strips- good for beneficials and propyzamide usage or are conditions to ensure chemistry appropriately to maintain efficacy,
will help slow the flow across the running any campaigns to remains effective against the reduce the risk of resistance and
field reduce pesticide losses target species and safe to the the impact on the environment of
● Retain surface trash
environment and users. these vital active ingredients.”
16 crop production magazine october 2021OSR herbicides will have already come through. overland flow was also at play. There was little evidence of late “Some trial plots showed emergence in the trials where substantial lateral movement of reduced rates of propyzamide propyzamide, either surface or had been used. The impact of sub-surface, due to a slightly reduced propyzamide rates on sloping site. One trial was ‘lost’ broadleaf weed control must not because of this movement,” be ignored, but there are more he comments. A reduced rate of 500g/ha propyzamide (on right) following an earlier alternative options now.” In light of these findings, what application of clethodim gave good control of blackgrass in the Essendon Stephen believes that should growers do to help reduce trial compared with the untreated (left). applying a well-timed application the passage of propyzamide into of clethodim would allow growers water? Rebecca believes it’s Rebecca also points out that It will also look at water quality to assess how well it has worked about doing everything possible any propyzamide product should and, eventually, this will help us before any decision about to reduce both soil and water only be applied once per assess whether this approach propyzamide application has to movement overland to reduce one season. She encourages farmers can be incentivised in target be taken. “If it has worked well, of the pathways of propyzamide to reconsider using different catchments. and drone monitoring can be flow. propyzamide products in “Some agronomists and useful when assessing this, then “These include using cultural sequence, at rates which would farmers may not be keen on you can start to look at reducing controls as a first port of call –– result in exceeding the statutory the idea of reducing rates of propyzamide rates –– particularly which means thinking about maximum dose per season of propyzamide. However, our in areas of the field which are at blackgrass control as part of a 850g/ha. field trial data suggests a a high risk of leaching or longer-term rotation, crop type, Affinity Water are funding more targeted approach of reducing where there’s a low density of cultivations, mechanical chitting, field trials in 2021/22, says the propyzamide dose rates in blackgrass.” stale seedbeds etc. company’s agricultural advisor, sensitive catchments could be One of the interesting “Then make use of the full Danny Coffey. “These will include one way of safeguarding observations made during range of blackgrass chemistry a larger scale field trial to drinking water supplies, the trial was that downward available, making sure if investigate whether the use of maintaining effective blackgrass movement of propyzamide propyzamide is used then it’s at reduced rates of propyzamide control and protecting the future isn’t the only way it can move the right time, right place and can be upscaled and successful use of propyzamide by applying into water. Stephen noted right rate.” blackgrass control maintained. it in a more sustainable way.” ■
Hold on a bit longer
“ The greatest
slowdown in the
movement of both
clomazone and
pendimethalin was
observed when applied
with Backrow.
”
Technical Pushing
performance
Keeping herbicides where young crop roots scavenge for nutrients pre-em herbicide active substances ––
they need to be is crucial for during the early growth stages. clomazone and pendimethalin.
“For weed control success, the herbicide The two herbicides were chosen for their
weed control, crop safety and must also be located in the top 5cm and be different properties. Clomazone represents
for minimising potential retained in this later so that there’s still a herbicides with high mobility and medium
lethal dose present to prevent subsequent adsorption onto soil particles, so its retention
losses to the environment. flushes of weeds that may germinate over in the top 5cm is most affected by rainfall
CPM digs into new research time. A longer presence of the herbicide in and wet soils. At the opposite end of the
this soil layer contributes to better uptake of spectrum is pendimethalin, which has low
which shows not all the active substance by germinating weeds, mobility and very high adsorption onto soil
adjuvants have the same which ultimately increases the effectiveness particles, hence its efficacy is most affected
of the herbicide,” he says. by dry soils.
effects on herbicide Soil cores (30cm deep, 6.7cm diameter)
movement in the soil. Reliability and safety were taken from an arable field in Wroclaw in
Herbicides vary in their physical properties, Poland using a Van der Horst core sampler.
By Lucy de la Pasture which means some are more prone to The cores were analysed and the soil texture
leaching down the soil profile than others. was found to be 73% sand, 21% silt and 6%
Stuart believes many pre-em herbicides clay, with a pH of 6.8 and maximum
Unpredictable weather patterns have often require additional support to keep water-holding capacity of 67.8%.
made herbicide applications more like them in the weed germination zone, The soil cores were treated with the
Russian roulette over the past two particularly during heavy rainfall events herbicide plus adjuvant mix in a stationary
autumns. For those drilling later to combat and in light soils.
blackgrass the game has become even “Adding an effective adjuvant partner to
more deadly, with the odds stacking up in the mix could offer the reliability and safety
the weather’s favour as herbicide spraying required and this has been confirmed in
opportunities diminish. trials where it’s been reported that some
Even if the game of chance has been adjuvants could help retain an active
survived and the pre-emergence is on and substance in the top 5cm for longer,
ready to do its job by sensitising or taking compared with when the herbicide is
out weeds as they attempt to push through applied alone.”
the herbicide layer, the weather can still Research conducted in the Netherlands
upset the applecart. during 2017 has already shown Backrow’s
Keeping residual herbicides in the top ability to retain both herbicide and moisture
5cm of the soil is more than just nice to in the surface layers of the soil, says Stuart.
have, it’s a must for safe and effective Earlier this year, new research was
weed control at the pre- and peri-em spray commissioned by Agrii and carried out
timings, says Stuart Sutherland, technical by the Institute of Soil Science and Plant Stuart believes many pre-em herbicides often
manager at Interagro. Cultivation in Poland. The aim was to require additional support to keep them in the
“The surface layer of the soil (0-5cm) is evaluate the effects of different adjuvants, weed germination zone, particularly with
particularly important as it’s the germination which included Backrow and two competitor increasingly frequent heavy rainfall events.
zone for many weeds and it’s also where the products, on the movement of two main
18 crop production magazine october 2021top performer, says Stuart.
“The addition of Backrow
significantly increased retention
of clomazone and pendimethalin
in the top 5cm of the soil. The
level of clomazone retained by
Backrow in the top 5cm had the
knock-on effect of reducing the
amount of active substance
found at 5-10cm and at 10-20cm
–– more of the clomazone was
Soil cores were taken to a depth of held higher up in the soil core
30cm from a sandy soil in Poland profile,” he says.
using a Van der Horst sampler. “With pendimethalin, the
percentage of active measured
spraying chamber in a water at 5-10cm was also increased
volume of 200 l/ha using a TeeJet significantly by the addition of
XR 11003-VS nozzle. After 20 Backrow, thereby also significantly
hours, irrigation was applied at reducing the amount of
20 l/m2 over a one-hour period to Pendimethalin lost lower down
simulate heavy rain. The soil at 10-20cm.”
cores were then extracted the So what’s the significance
next day and cut into samples to of these findings? Stuart says
represent soil layers of 0-5cm, the research draws out the
5-10cm and 10-20cm. differences between the two
The core samples were initially herbicides on this soil type.
frozen, then thawed prior to “Pendimethalin is
analysis and the core sections characterised by its lower
mixed, with three replicates taken mobility into the soil under the
to give statistically significant influence of rainfall compared
results. The residue analysis with clomazone. This was borne
was performed according to the out in the results which showed
procedures developed at the approximately 10% more
Institute, which consisted of three pendimethalin remained in the
basic steps –– extraction of the surface layer of the soil, which is
herbicide active from the sample a direct consequence of its
matrix; purification of the extract; chemical properties.”
and lastly analysis using gas Perhaps of most interest was
chromatography for the the difference between the
pendimethalin core samples and adjuvants in terms of their
liquid chromatography for the effect on the migration of
clomazone treatments. both herbicides through the
So what did the results show? core profiles.
The adjuvants varied greatly in “The greatest (statistically
their influence on the retention significant) slowdown in the
of both herbicides, with movement of both clomazone
Backrow standing out as the and pendimethalin was observed
▲
Percentage herbicide residue, 0-20cm
Source: Prof Mariusz Kucharski, Institute of Soil Science and Plant Cultivation National Research
Institute, Wroclaw, 2021.You can also read
