BGTF Podcast: Weed control in spring 2017

Dr. Black Grass:                 Hello and welcome to the first Dr. Black-Grass podcast of 2017. In this edition we're going to be discussing the effects pre-em programmes last autumn and what they mean for control this spring. We'll also touch on spring crops for those people using it as a cultural control of black-grass.

                                                First of all, we're going to hear from four of Bayer's field team. Darren Atkins, Gareth Bubb, Sam Harvey, and Jack Hill. You'll hear them discuss how pre-em has performed in their part of the country and what that means for control ahead.

Darren Atkins:                   Yeah very much down east and inside of the country. We've, this year, seen a sea change swap across very much to later drilling really, a lot of crops on heavy black-grass infested land weren't drilled til mid-October through to mid-November, trying to allow for flushes of black-grass pre-drilling. Those flushes didn't come til late but I believe that the November drill crops will definitely benefit from that extended period where black-grass could flush. It's also given us the benefit that the later drillings got cool and more moist soil so the pre-emergence herbicides should work better.

Gareth Bubb:                     In the last three or four years, we've definitely seen an increase in deliberate delayed drilling for the grass-weeds - black-grass and rye-grass - this season, particularly more-so given how dry it was early so it was a sort of forced arm as well. Which has led to the pre-emergence herbicides being put on later when it's cooler, more moisture availability, and doing a good job and even where they weren't so successful in the very pre- timing, the very early, peri, post timing, appear to be doing a good job. I got a lot of calls about early applications of Atlantis and Hamlet in combination with Liberator, where there was the need for that early post-em activity. So far, outside of the very early drilling in dry conditions, control seems to be, at the minute, to be quite good. But it's early days as we've learned from last year.

Sam Harvey:                       We've got more of a black-grass problem encroaching west. I see it on a lot more farms last year than I've ever seen it before, in fields where I've never seen a problem before, so it's moving over there. I'd say the jury's still out on how well we've controlled it this autumn. But I think I agree with Bubb, the frost would definitely help.

Gareth Bubb:                     I think the fact we've had more frost by the new year than the combined total of the last two years has been a critical need really, whether it be dampening disease pressure, pest pressure, but more importantly preventing the black-grass outgrowing the residual herbicides that we laid down early on in the season.

Darren Atkins:                   I think we've seen a lot more residual herbicide going on this autumn even though the crops are probably drilled later, whereby we've had an initial pre-em timing of a flufenacet-based product going on, probably Liberator. Then we've had the peri-em top going on as well so we've had a quite a high amount of residual chemistry going into the soil, which hopefully will benefit on the long-term for grass-weed control.

Jack Hill:                               The late drilling message has definitely sunk in more this autumn than it has done in previous years. It was well documented that there was going to be very high levels of black-grass dormancy this autumn. Also the openness of the autumn and the dry conditions that we had, guys weren't in a massive rush to get out there with the drill, which is good news from a black-grass control perspective. Because they were drilling two or three weeks later than they would have done in previous years.

Darren Atkins:                   I’d hope that the later drilling and the fact that the grass weeds are growing more slowly, in theory that should mean that the weeds’ roots are in a herbicide active zone for longer, they're growing more slowly through it. So they should be picking up active ingredient for a longer period of time, so you would expect that would mean you would get high levels of control.

Dr. Black Grass:                 Thanks a lot.

                                                Next up we'll hear from another Bayer team member, Jon Helliwell. I caught up with Jon in a field in Oxfordshire earlier this month, where I asked him, "what are the main priorities for farmers at this stage of the season?"

Jon Helliwell:                      They'll be thinking about their post-ems, but personally walking a couple of oilseed rape crops recently, there's still very clear active light leaf spot in some of the varieties, certainly in varieties less than a six. So I'd really urge growers to get out and walk their oilseed rape crops first if they've got any, and check for that light leaf spot. I think that's the first job.

                                                Following that, as growth starts, conditions start to pick up, certainly a post-em application would be on the cards it the weed pressure dictates it.

Dr. Black Grass:                 Okay and what kind of conditions and factors should I take into account before making a post-em application?

Jon Helliwell:                      When looking at post-ems, they're success really is dictated largely by the weather. Historically, growers are focused on temperature, but actually if you've got a day where you've got good sunlight levels, not overcast and not cool, the weed will actively grow. A key indicator really, and one thing we recommend is, just look out your window, look at your lawn, is your lawn actively growing? Because chances are, if you've got active growth of your lawn, the black-grass will actively be growing at that point as well.

Dr. Black Grass:                 Some people who've grown lots of weed crops over the last ten or twelve years and have applied a fair amount of Atlantis or similar products have probably experienced some degree of resistance and at this stage in the season there's often a decision of, "do I apply or not?" What would you say to people in the process of making that decision?

Jon Helliwell:                      Well certainly in that particular situation, where growers have used oilseed rape and wheat in quite close rotations, yes Atlantis will have been extensively used. It's quite clear the effects of Atlantis may be reduced over that scene ten years ago. But certainly looking at some of the control levels that we still get, it still gives a very, very useful level of control in black-grass. It’s worth remembering that actually not all plants are resistant in the same way - it's all about managing that seed return.

Dr. Black Grass:                 Thanks a lot Jon.

                                                For those dealing with black-grass with some level of resistance, opting for a spring crop has proven to be quite a popular option over recent years. In the next section well hear from Andrew Cotton and Paul Drinkwater from last summer's Black-Grass Live events, talking about spring cropping.

Andrew Cotton:                Spring cropping is the answer where you have got resistance as a problem, but it doesn't alter the dynamic. So if you're spring cropping a year or two, with a large seed bank of resistant black-grass you're going to hopefully finish that period with a smaller seed bank but it'll still be resistant. So it doesn't alter the dynamics.

                                                Yes, resistance is a problem in spring crops per se, and how we control black-grass in spring crops is a challenge. For instance, spring wheat, we at the moment don't have any EAMUs for Flufenacet use, and apparently the companies were told to go and get full clearance and that's not yet been forthcoming. And we've lost Avadex use on spring wheat as well. So that's a whole area that I think is vital that we get some movement there. But spring barley, there's some good options there with Avadex, and half-rate Liberator, half-rate Crystal and that's great, and you've got a competitive crop as well.

                                                Spring oats, you don't need herbicides because they do it for you. Maize is very good because we've got Bayer’s MaisTer which has a good go at black-grass that other things don't reach. And obviously there you've also got a competitive crop and I'm sure competitive crops - basically what you must try and avoid is seed return in the spring crop phase. So that in fact you get this 70% to 80% reduction through degradation in the ground, and you get no extra return there, and that's what we’re trying to do.

                                                I've got clients who have spring cropped for three years on severely bad situations. Then perhaps had [inaudible 00:08:45] and are back into wheat now and we can live with it. That's what you're looking at really to get on top of some of these very bad populations.

Dr. Black Grass:                 Before we move on to hear from Paul, I'd like to note that since this was recorded, Liberator has been approved for use in spring wheat. It has a label approval for annual meadow-grass control at 0.3 litres per hectare, up til growth stage 14 of the crop. Liberator is also available in spring barley on an extension of authorization for emergency uses via EAMU.

Paul Drinkwater:              We grow lot of spring crops, we don't grow spring wheat or spring barley at the moment at any great extent. So we've got peas and beans, sugar beet, potatoes and it's a problem in all those crops. They used to be our cleaning crops. If you look historically, we lost the graminicides first, we ended up, we could still manage with the peas and beans because our cleaning crop was actually wheat. Atlantis was so successful that we could live with it that way. Now we've got a problem in the spring crops because a lot of the spring crops we've got are fairly open. Sugar beet we've got Centurion Max which has worked very, very well this year and was pretty much a failure the year before, for whatever reason.

                                                It is becoming more and more of a problem, it's difficult to control. We’re getting more and more spring germinations; that is probably because the seed bank is getting bigger. If black-grass is clever enough to breed resistance to all these chemicals, surely it's clever enough. We've selected out the populations so we've probably got more spring germinating black-grass. So we’re looking at spring barley, and spring barley is fine but I think it's an April drilling to really get the best out of all the cultural controls we’ve got.

Dr. Black Grass:                 Thanks a lot Andrew and Paul, and to all the other contributors to today's podcast. That's all we have time for this month, but you can keep in touch until the next edition by tweeting @DrBlackgrass. Until then, goodbye.


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