BGTF Podcast: Getting prepped for pre-em

Read the transcript of the podcast below.

Dr. Black Grass: This is episode 5 of Dr. Black Grass On Air. We're already in the second half of August, so in today's program, we're going to start to think about herbicides. Mainly pre-emergence, but also a little bit about post-emergence products. These products won't be going on for a number of weeks yet, but getting prepared in advance gives you the best chance of success. In July, I spoke to David Rushmore of Hutchinson's, an agronomist who covers the area near Wisbech. In this area, some soil types are particularly challenging for black-grass control, so they need a robust cultural pre-em and post-em program. David told me more about this.

In this area, sort of Lincolnshire fens, what kind of problems do people experience with black-grass and other grass weeds?

David:  I've said once or twice before, we find that where there's good silt soil or a sandier soil, then we have not such a serious problem. It's more on what we would call 'drummy soil', where there's a high organic or high KD factor. Unfortunately, a lot of the pre-emergence herbicides are not doing quite the job that we were hoping they would do.

Dr. Black Grass:Why is that?

David: I think the product goes on to the field and it gets absorbed by some of the organic material in the soil rather than perhaps doing a full 100% job.

Dr. Black Grass: How does that affect the overall program and the strategy for control?

David: We must try and do more of the scratch and spray technique so we try and get as much black grass to grow before we actually put the seed into the ground. Once we've done this, one or perhaps, two glyphosate treatments, we try and delay drilling so that we've taken off the biggest flush of black grass. Then, we try, obviously, to give it a good belt and braces pre-emergence treatment. In my case, I like the product Vigon, which is a Bayer product, and I usually link with that Defy, about three litres of Defy, and a litre of Vigon. That is holding the black grass fairly well, even in the difficult situations.

Dr. Black Grass: Okay. You don't think it's doing as well it would do on other types of soils?

David:No. On the silt and sand soils, we're finding some pretty good control. Some times this last year, we didn't even have to follow up with a post-emergent. But in most of the organic material soils, we've had to follow up with a very early dose of, in our case, Hatra and Biopower, which is the liquid version of Atlantis. That seems to knock it a second time, but the black grass in some fields did get away.

Dr. Black Grass: Okay. You said an early application of Hatra. What kind of timing where you looking at there?

David:That was just at the early peri-emergence. Sort of one and two leaf of the black grass. The smaller the black grass, the better the chance of controlling it.

Dr. Black Grass:Okay. Would that be sometime in November?

David:Yeah, a lot of it was done either late October or early November and that did seem to help.

Dr. Black Grass: Okay. You said that in your area, there's more and more delayed drilling. How would you say that changed over the last ten years?

David: It's certainly ... Farmers have had to rethink their programs because ... Go back ten years, and a dose of the new product, Atlantis, on a black grass plant meant certain death to that plant. The resistance has built up severely now and so a lot of sites where we've been testing have got up to triple R resistance for post-emergent herbicide, and therefore, there's no magic bullet anymore. Consequently, we've got to be a lot more diligent with the pre-emergence treatments.

Dr. Black Grass: Delayed drilling, diligent pre-emergent treatments are two aspects. What other aspects of cultural control are you starting to see become more and more commonplace?

David: It seems funny, actually, but we had several farmers running away from the plough and doing a minimum tillage. Actually, we're now looking at some returning to the plough. Hopefully, only once every three to four years, rotational ploughing. We are finding that farmers who had decided that ploughing was probably actually giving a worse seed bed and more problems, are actually find that they're having to get back to getting some more cultural control by the plough.

Dr. Black Grass: Okay. Is that on all soil types or are certain soil types more conducive to control from the plough?

David: I think the heavy soils and the more organic soils are certainly seem to be making use of the plough. Does seem to be burying some of these more difficult seeds. I think the lighter soils still seem to be okay with a scratch and spray and minimum tillage technique, really.

Dr. Black Grass: Okay. How are things shaping up this season? Has it been a good year for black grass or a bad year?

David: Thankfully, there was plenty of moisture in the Autumn, and therefore, the residual herbicides do seem to have done a pretty good job. We have concerned on some farms. As I said, on some of these more organic soils, I have gotten nasty patches of black grass in some fields. We've had farmers who have actually burned parts of fields off rather than allow the black grass to seed down. As the old adage goes, "One year's seeding is seven years weeding." So we've tried to control the black grass by post-emergent controlling with glyphosate, but you don't really want to be doing that because you're obviously taking your crop off as well.

Dr. Black Grass: Finally, you mentioned that people have had good control this year. What should they be looking out for this autumn to make sure they can capitalize on getting some good control?

David: I think, certainly as I say, delay the drilling and look for soil moisture. Perhaps, try and make sure the seed bed is as fine as is possible. I like to do drill the crop and roll it, but there are some schools of thought where rolling could actually exacerbate and bring more black grass up. If we can get it rolled and then get the application ... I think the application technique is important. Several growers are going on to a certain nozzle, with an angled nozzle on the sprayer that does give a few more percent. Any few percent is better than nothing. If the job is done accurately with a good 200 litres a hectare and a flat fan nozzle, I think it can do a good job as well.

Dr. Black Grass: As David explained, on the most challenging land, the whole program needs to be well planned and well executed. His pre-em combination of choice was Vigon plus Defy. For those of you unaware, Vigon is a combo of diflufenican, flufenacet, and flurtamone pre-formulated. It is similar to Liberator and Bacara in a tank mix.

What are the best options to use at pre-em? For several years, Bayer has run weedscreens at a number of sites across the UK. One of these sites is at Cawood in Yorkshire. Early this year, I spoke to Darren Atkins and he told me a little bit more about what's going on that this site.

Darren Atkins: Weed screen is a way of us looking at comparative treatments on different grass weeds. What we've got here is grass weeds drilled into a plot and then treatments applied across those plots. We're looking at comparative treatments in an even situation for grass weeds. As you can see, in the untreated, it very much got all the grass weeds, black grass, rye grass, annual meadow grass, bromes, and wild oats. In the untreated, we've got a fair population of everything grown up as you'd expect. So we start looking at pre-emergence treatments really. The base treatment of Liberator at 0.6 applied in a true pre-em situation, has worked very well. We've got reasonable levels of control of meadow grass, black grasses, brome species. There's a few wild oats there, but on the whole, without the over-spray of a post-em treatment. It's done a very good job.

We've looked at various additives to Liberator. We've looked at Liberator plus pendimethalin, Liberator plus Lexus and Liberator plus Defy. All of which, add to varying degrees of control to different grass weeds species. Personally, one of my favourites is Liberator plus 2 litres of Defy. It's elevated black grass control and given us additional control on rye grasses and to some extent the wild oats as well. It's quite useful additive treatment to a straight Liberator.

What we've also looked at is what happens if pre-emergence treatments don't go on a true pre-em timing. We've got delayed pre-emergence treatments which were put on up to a month after drilling and you can see there's a significant drop off in performance where we missed that true pre-emergence timing. I think it's important to plan and apply your pre-emergence treatments within three days of crop being drilled, if at all possible.

Dr. Black Grass: What exact dates did these treatments go on? When were they drilled?

Darren Atkins: Drilling was very late September and the pre-em treatments went on the first of October. They were within three days of drilling. Where we've gone a month after drilling, two months after drilling, three months after drilling, with the residuals, Liberator, we've seen significant drop offs in control. The later you apply, the less control we're getting.

Dr. Black Grass: Okay. What about post-emergence treatments?

Darren Atkins: This weed screen, we are looking at sequences with Atlantis and we're getting reasonable levels of control. But what we're seeing is that the Atlantis really does need a pre-emergence treatment applying before the Atlantis goes on. You need that sequence to get complete levels of control. We've also compared Atlantis to various other products from other manufactures. We've compared it to Unite and we've compared it to Broadway Star. What we're seeing there is, whereas the Unite and Broadway Star are actually quite reasonable on bromes and rye grasses and wild oats, where it comes to black grass, they are not as strong a black grass product as Atlantis or Pacifica is.

Dr. Black Grass: What sort of timing were you putting Atlantis on? What it an autumn time or what you might call a spring timing?

Darren Atkins: We've got a range of timings here for Atlantis. Autumn timing running through from November and December timings all the way though until late March and early April. What we're finding is, where we've got difficult-to-control grass weeds, it's always better to apply Atlantis in the autumn where possible because we're getting elevated levels of control above what we're getting in the spring. Back down at the Chishill site in Hertfordshire, we do drill very resistant black grass down there and we're finding, even more so in that case, it is vital to get the Atlantis on in the autumn because spring applications there onto highly resistant black grass, it’s really struggling.

Dr Black Grass: And if you want to take a closer look at what Darren has just been talking about then visit where you can compare the effects of different treatments and timings by looking at images taken at the weedscreens.

Wheat harvest is finally getting underway despite the heavy rain towards the end of last week.  Early results from the south west and the south east are very good with above average yields and very good quality, although so far it’s been mainly milling wheats that have been brought in, and we wait to see the results from feed wheats soon.

According to ADAS the winter barley harvest is now over 90% complete with yields of 7.2 to 7.4 tonnes per hectare on average, this is up to 14% higher than the 10 year average.  Oilseed rape is 80% complete with yields 5 – 11% higher than the 10 year average of 3.4 tonnes per hectare.  You may remember that a couple of weeks ago we heard from Jonathan Hodgson on his harvest, he now has the results from his oilseed rape yields and they’re very good; they’ve ranged from 4.7 to 5.4 tonnes per hectare depending on the variety.

If you have any news or information on harvest on your farm please tweet us @drblackgrass.  In next weeks programme we’re going to look at how you can plan and prepare for post-emergence sprays by sorting out any drainage problems you might have on the farm, I hope you can listen with us then.  Goodbye

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