The RPA Podcast - Episode 15

Welcome to the fifteenth episode of The RPA Podcast. In the latest episode, we look at a topic that generated a lot of interest when we covered it on the RPA blog in May last year, Integrated Pest Management or IPM.

Last year we explored the research being done to help farmers tackle pests, weeds and diseases more sustainably and the funding available to help farmers get involved. Since then a lot has been happening putting these practices into action, both in the research field and on farms.

On this episode of the podcast we talk to four guests to find out how things have moved on - Dr Sam Cook and PhD student Charlotte Robb, from Rothamsted Research. And farmers Chris Gemmill and Fergus MacGregor, who have been working with the team at Rothamsted, sharing their experience on how they use IPM, as well its cost effectiveness and the challenges they face on their farms. 

The discussion covers Rothamsted’s research into IPM, pesticide resistance and its future, flowering field margins, and the range of digital tools available to farmers to help plan and implement IPM.  

The RPA Podcast is an opportunity to engage with farmers and land managers in a new way, and we encourage you to contact us with suggestions of particular topics that you’d like us to cover with our subject experts. You can email us at External.Affairs@rpa.gov.uk.

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Transcript

Transcript – The RPA Podcast episode 15 

Caroline: Welcome back to the RPA Podcast. I'm Caroline Ling and today we're returning to a topic that generated a lot of interest when we covered it back in May last year, Integrated Pest Management (IPM).

Last year we explored what IPM is, the research being done to help farmers tackle pests, weeds and diseases more sustainably and the funding available to help farmers get involved.

A lot has been happening since then, both in the research field and on farms putting these practices into action. Today we've got four brilliant guests to find out how things have moved on.

We have Dr Sam Cook and PhD student Charlotte Robb, both from Rothamsted Research, who've been working on some fascinating research into natural pest control and how farmers can reduce their reliance on pesticides. We're also joined by two farmers who've been putting IPM into practice on their own land, Chris Gemmill and Fergus MacGregor. Both have been working with the team at Rothamsted and have some really valuable on the ground experience to share. Charlotte, let's start with you. Can you give us a quick introduction to yourself and your work at Rothamsted Research?

Charlotte: I'm a third year PhD student studying regenerative agriculture for mustard, with a specific focus on integrated pest management. This research is funded by Unilever and the work's carried out at Rothamsted and at Reading University. My work looks at how implementing different regenerative techniques can reduce insect pest damage naturally while maintaining yields, therefore reducing the need for harmful synthetic chemical pesticides. Ways that this insect pest damage is reduced is by encouraging more natural enemies to the field or by diverting the insect pests away. It's all about working with nature rather than against it. This is beneficial for many reasons - it's more cost effective for the farmers, it means pest control is more resilient and it's also more environmentally friendly.

The regenerative principle that I'm mainly focusing on is crop diversification and I have two experiments that are looking at companion planting. One is looking at the effects of under sowing on mustard cultivation and the other is looking into potential trap crops for mustard.

Caroline: It was interesting you touched on that because last year's blog highlighted how your team's research into companion crops and natural pest predators is helping farmers protect mustard crops most sustainably. Can you give us an update on how that research has developed since then?

Charlotte: I've got a field trial currently underway at Rothamsted looking at the effects of under sowing oats in mustard crops. The hypothesis for this is that under sowing mustard crops with oats will reduce cabbage stem flea beetle infestation and will also support beneficial insect populations, therefore increasing biological control. This field trial has 32 plots which cover white, brown, spring sown and autumn sown mustard - all the different variations of mustard that people grow in England. Half these plots are under sown with oats and half aren't. I'm monitoring insect pest and natural enemy abundance on each plot using pitfall traps - cups in the ground that ground-dwelling insects run and fall into, and water traps - yellow bowls on sticks with water in that flying insects go into. This trial is still ongoing. It's on the field right now. I don't have the results yet, but watch this space.

Caroline: We will have you back to find out the results. Thanks, Charlotte. A question for Sam. Your work also looks at encouraging natural pest predators and the use of trap crops alongside mustard. Can you explain what that means in practice and whether there's been any progress in understanding how farmers can create the right conditions for those predators to thrive?

Sam: I've been working on trap crops for a long time. Back in 2006 we started this work on cabbage stem flea beetle and we found that if you surround the oilseed rape plots or fields with turnip rape, which is a close relative of oilseed rape, the cabbage stem flea beetles actually prefer that species to oilseed rape, so they're lured towards that and go to eat the turnip rape, lay their eggs and they leave the oilseed rape alone. We found we could reduce the number of larvae, so farmers didn't have to spray those plots and also reduced the damage caused if we had turnip rape surrounding the outside of the fields. We've started to look at the best position for trap crops and our research has shown that they can be used to reduce pollen beetle pests in oilseed rape if you plant a border of turnip rape around the outside of the field.

But for cabbage stem flea beetle, it seems to work best if you put the trap crop in the middle of the field. There's quite a lot of work we still need to do, but Charlotte's work is really trying to apply what we understand and know about turnip rape or trap cropping in oilseed rape and transfer that to mustard because it's got a different phenology and slightly different pest complex. It may or may not work, but so far it looks like it could reduce the insect pests. Another thing we found with turnip rape trap cropping was that the trap crop flowers much earlier than the oilseed rape crop and that attracts all the natural enemies, the predators, particularly parasitic wasps of the pests. They are attracted into the area much earlier, so by having trap crop situations, farmers could bring those really beneficial insects into the field to control their pests naturally.

Caroline:  Pesticide resistance is another area you're working on, and it's something the UK government has been taking seriously, as reflected in the UK Pesticides National Action Plan published last year. DEFRA have been funding work looking into how to develop a more robust resistance monitoring scheme. How significant a challenge is pesticide resistance right now in mustard and brassica crops and what role does IPM research play in addressing it?

Sam: Pesticide resistance, particularly pyrethroid resistance, is a massive problem. Pyrethroids are the most commonly used insecticides in the UK and since the revocation, or the banning of the neonicotinoid seed treatments and sprays back in 2013 and 2014, farmers of brassicas in particular have nothing left to use to control pests in their crops because of high resistance to pyrethroid insecticides. Resistance in cabbage stem flea beetle is something we've been studying since 2019. My colleague Caitlin Willis published her PhD on this subject and showed that pyrethroid resistance was quite widespread in the UK. Myself and my colleague Patricia Ortega-Ramos have been studying this, taking it forward since 2019 and we've now shown that pesticide resistance to pyrethroids in cabbage stem flea beetle is pretty much countrywide. There are some areas of Scotland that don't have any resistance, but everywhere else has very high levels of resistance to pyrethroids. Unfortunately, this means that farmers don't have anything to use to control those pests, which makes other IPM tactics really useful. We've been running a scheme where we've been asking growers of oilseed rape and brassicas to send us samples of their live flea beetles from their harvest bins and that's what we've been using to gather these data. But at the same time, we've been looking at the parasitisation of the cabbage stem flea beetle. There's a parasitic wasp that lays its eggs inside the beetle. The larva develops inside the beetle and kills it when it exits the host and when it's ready to become an adult. So those parasitised beetles are already dead and don't need killing with pyrethroid insecticides. We've been running this monitoring scheme since 2019 and have shown that this parasitic wasp, Microctonas brassicae, is also widespread across the UK and parasitisation levels can reach 10 to 15%, so it's really important that we really understand what we need to support this parasitoid in the environment so farmers can boost the beneficial biological control that's possible on their fields, which will negate the use of pyrethroid insecticides.

Caroline: Sam, I've heard that flowering field margins can attract beneficial insects into a farmer’s main crop. I wonder if you could tell us a little bit more about this?

Sam: Flowering field margins started to become popular because it was realised that they attract beneficial insects, particularly pollinators, to the agricultural environment. But we did quite a lot of research and we also showed that not only do they attract more bees and butterflies and pollinators, but they also attracted the natural enemies of crop pests. We were really interested in trying to develop a bespoke flower rich margin that would help pest management in oilseed rape crops and this is some work that DEFRA funded a few years ago from 2015 to 2018. We found that because most of the natural enemies of oilseed rape and mustard crops are brassica specialists, if those flower-rich margins have brassicas in them, then they really did attract those natural enemies into the crop. 

As I've already mentioned, turnip rape attracted the parasitic wasps into the field when they're planted as trap crops, but flowers in flower-rich margins can also play a really important role in luring those natural enemies into oilseed rape and mustard crops, particularly forage rape and the radish species. So, if any farmers are growing flower rich margins, I would encourage them to think about including those species into the mixtures. And I know it's not quite related to flower rich margins, but a lot of farmers are growing cover crops at the moment before their spring crops and Charlotte and I are investigating the role of the brassicas in those cover crop mixtures to provide trap crop services. They're luring in the cabbage stem flea beetle, again like the turnip rape trap crops, to feed on them and lay their eggs and then of course those cover crops will be destroyed in February before the flea beetle can complete its life cycle. This is work that's funded by AHDB and DEFRA are playing a part in that. 

Our partners are ADAS and NIAB and Harper Adams University and we hope that within the next year we might have a really good answer to give to farmers as to the role that cover crops can play in attracting natural enemies to the agricultural fields to help in pest management.

Caroline: Moving back to Charlotte, for farmers who might be listening and wondering whether research like yours translates into practical advice they can use, what would you say to them and how does working collaboratively with farmers like Chris and Fergus shape what you do?

Charlotte: My work prioritises working with the farmers and this is so I can learn from their expertise in farming and also understand things from their perspective. I really want to ensure that any advice or recommendations I give are practical and can be easily implemented on the field. The very first thing I did in my project was survey the English Mustard Growers Group to determine what their perspectives and experiences of regenerative agriculture were. And since then, I've based all my work on the results from that survey. Additionally, I've been monitoring insect populations on eight different farms in England, covering white, brown, autumn sown and spring sown mustard to create a timeline of which insect pests and natural enemies are present in different types of mustard at different crop growth stages. This work is still ongoing and I'm visiting the farmer's fields monthly. It should be a two-way process - the farmers inform the research and the research supports the farmers.

Caroline: From a research perspective, Charlotte, what are the biggest gaps or unknowns that you're still trying to answer?

Charlotte: In terms of mustard, integrated pest management is still relatively unexplored. The questions that my project specifically is hoping to answer is what insect, pests and natural enemies are present in mustard crops at different times across the whole growing season. Does under sowing with oats affect insect, pest and natural enemy abundance? And what crops can act as effective trap crops to protect mustard from pest damage? Here are a few examples of really interesting areas to look into - how does zero tillage versus reduced tillage versus conventional tillage affect insect abundance? How can the implementation of wildflower strips most effectively support natural enemy populations and how does the incorporation of organic matter affect insect populations? But the key thing to remember here is that all farm circumstances are different, so will require different practices to effectively control their insect pest populations. It's not a one-size-fits-all approach and in fact, what I think is really important is that we encourage farmers to explore and try out different techniques on their own farm and see the results for themselves.

Caroline: From your perspective working with farmers, do you think there's enough support out there for those farmers who want to transition towards more IPM-based approaches?

Charlotte: Reducing pesticide use can feel like a big risk for farmers and that's why I think that clear evidence is needed. I think ways to get that clear evidence is more research into IPM-based approaches, specifically field trials that can be more applicable to the farmers’ situations.

Caroline: To finish on a forward-looking note, Charlotte, what are you most excited about in terms of where IPM research is heading in the next couple of years?

Charlotte: I'm really excited about developments in digital insect monitoring, including the use of AI to automatically identify insect species. This is great because it would save the taxonomists in the lab so much time identifying insects so we could do more research overall. Also it would hopefully mean that we no longer have to kill the insects, especially the beneficial insects to monitor them.

Caroline: And now to farmers, Chris and Fergus. Thank you so much for joining us today. Perhaps we could start with you each telling us a little bit about your farms and how you first got involved with IPM and the work at Rothamsted. 

Chris: I'm Chris Gemmell, farm manager for Law Farming, which is a 2,000 hectare mixed farming business on the Hampshire border. We're mostly combinable crops and sugar beet. And we're predominantly light to medium soils all over chalk in the area around here. We first got involved with Charlotte in early 2025 when she was looking for some farms to host her insect traps and monitoring in the mustard crops. As we were relatively new to growing mustard, we thought it was a good opportunity to try and learn a bit more about the crop and what sort of insects and pests we might be facing and expand our knowledge.

Fergus: I’m Fergus MacGregor. I work at the family farm at MacGregor Farm Partnership in Reedham, Norfolk. We're a 500-hectare mixed arable and beef farm. We're organic, so we grow most of our cereal crops organically. We also have a 100 hectare conventional farm on the other side of Reedham, so we're very mixed in what we do. We are fully irrigated on reasonably light land growing, which we also grow some veg on, as well as our cereal crops. We grew mustard for two years, and it was second year that Charlotte came over to get involved. We thought it'd be interesting to see what pests she could find in our crop. And it's been an interesting experience checking the traps and seeing what's in there and learning more about the insects on the farm.

Caroline: Chris, when we think about IPM as a whole farm approach, using all available methods to prevent, monitor and control pests, weeds and diseases, it's one thing to understand the concept and quite another to actually implement it. Can I ask what IPM looks like on your farm on a day-to-day basis now?

Chris: In the broader context of IPM, it's involved in every decision we make and before any crop goes in the ground, we're looking at crop rotations, varietal choices, in their known weed or disease or insect pressures that we may face around the farm.

It’s an ever ongoing evolution of that and a continued monitoring process throughout the year, seeing how things change through the growing season and how that picture changes and what tools we have available to deal with that. The last approach is a chemical application, but there's a lot that goes into the planning to try to minimise that wherever possible.

Caroline: And Fergus, what about you? Has your approach evolved over the past year or so? Have there been any particular changes or practices you've introduced that have made a noticeable difference to your mustard seed crops?

Fergus: Being organic we were already using biological controls and we have a fairly extensive CS scheme. And we also have an involuntary companion crop in all our fields through the weeds being organic! We find that compared to the conventional farm, we don't have as many insect pests because there's an abundance of predators. We weren't particularly worried when we grew the mustard in terms of pests coming in.

I suppose we haven't really changed our practices at all, but it has been a very interesting process finding out about what's actually living in the field.

Caroline: Mustard crops can face some real pest pressure at different stages of the growing season. Coming back to you, Fergus what are the most significant pest challenges you're dealing with when it comes to your mustard seed crop? And has working with Rothamsted changed how you approach managing them? I'm then going to ask the same question of Chris.

Fergus: The farm has been organic for 27 years and we don't really see having pests as a problem. We obviously have issues with disease, but that then comes down to drilling dates, etc. It's more obviously trying to grow a good crop. We find that having hedgerows and other spaces allowed for the propagation of a great variety of insects.

Caroline: And Chris, have you found that any of the research coming out of Rothamsted has directly changed your decision-making around pest management in your mustard seeds?

Chris: Not necessarily in our mustard as yet, but as Fergus said, it's been really interesting seeing the abundance of insects in the crop and how that changes through the growing season. Certainly other things came out of Rothamsted over the years - their aphid forecasting which we use in the mustard to get a view on aphid pressure and Virus Yellows, that's used very readily so there's a lot of tools and research coming out of these institutes which is really useful.

Caroline: One of the things that has really developed in recent years is the range of digital tools available to help farmers plan and implement IPM. Sam, can you tell us about some of the tools that are out there, things like the ADAS and SRUC IPM planning tool and how they can help farmers like Chris and Fergus.

Sam:  As you mentioned, the IPM planning tool, which was a collaborative research effort between ADAS, the NFU, SCRUC and the voluntary initiative. And this IPM planning tool tries to help farmers to fill in the form. It tells you how to set up and produce a plan, how to produce the reports needed and it also gives interesting and useful advice on IPM in general, in arable systems, grassland and horticulture. And there's some written guidelines on IPM in different crops, including brassicas and on oilseed rape specifically. I would encourage farmers to check ipmtool.net. Also, quite a few commercial companies have now got monitoring tools, which I won't mention, but just do a quick web search, but I would also point people to the AHDB website. There are quite a few tools on there that are freely available, for example, the Sclerotinia Risk Monitor, the FOMA Risk Assessor, the Barley Yellow Dwarf Virus Risk Assessment monitor, which helps farmers to understand whether they're likely to need to spray those crops against pests, weeds and diseases. 

I think IPM digital monitoring is exploding at the moment. There are lots of companies and research institutes that are working towards this, so monitoring and digital planning for IPM is going to become much easier. At Rothamsted, we've got a couple of projects and I've got a PhD student who's trying to automate the process of understanding how much leaf area has been lost to flea beetles. The current damage threshold is that if 25% of the leaf area damaged has occurred, then farmers should spray their crop with pyrethroids. But it's really difficult to assess whether or not 25% of the leaf area has been lost. You’ve literally got to crawl around in the mud to do that accurately. So digital tools where you can point your camera at the crop and it'll tell you whether or not you've surpassed the threshold, will really help. We're also trying to develop tools so farmers can automate larval infestation monitoring practices. We're working with a company called BugBug who are trying to automate hearing insect larvae inside the stems of plants, so hopefully, farmers will be able to predict whether their thresholds have been breached or not. There's all sorts of things - automated precision, accuracy on farms - so really understanding where the pests are in the field and only spraying those areas where there are hot spots of pests are coming soon. Hopefully those systems will also be able to notify growers when there are enough natural enemies in the field so that maybe they don't need to spray insecticides.

Caroline: A lot of these tools, are these genuinely accessible to farmers who perhaps aren't particularly tech confident?

Sam: Good question. Quite a lot of the tools do need some computer literacy. Some of them need quite a lot of farmer details and data. They are still revising some of the systems using farmer data, which some farmers might not be comfortable with. I would urge farmers to check the small print before signing up that they're happy that their data is used. But the IPM planning tool is relatively easy and is a really great place to start, and even I can do that one!

Caroline: For those who haven't come across it, the ADAS and SRUC IPM planning tools are designed to help farmers and growers monitor, prevent and control pests sustainably with a strong focus on reducing pesticide reliance. It covers things like crop rotation, planning, biological controls and pest forecasting. Chris, have you been using any of these tools on your farm and have you found them useful?

Chris: Definitely. They're very useful tools for planning and seeing a broader overview and having to plan rotation and things like that. There's a lot of useful tools out there to help with this decision-making process and quite often this is done in people's heads naturally, so it's good to get it into a more structured format.

Caroline: And Fergus, what about you? These tools are also increasingly relevant for meeting assurance standards such as Red Tractor. Has that been a driver for you in terms of getting to grips with IPM planning tools?

Fergus: We don't use any planning tools but I think they would be useful for us to implement. We've done carbon audits across the farm for some of the veg that's grown here. We've had a look at biodiversity surveys, etc., and I think we should be using them more often and do a little more research, and again, it comes down to time. We have a small team, so it’s about looking at what's most useful for us in the short term. I was just thinking about it when listening to Chris's response; we don't worry about the pests as it's something we can't do anything about being organic. 

Caroline: IPM sounds great in principle, but it's not without its challenges. A question to both of you. Has there been anything that hasn't gone to plan or anything that's been harder than you expected?

Chris: Yes, and I think Fergus put it quite well. Sometimes you can plan for all these things and they still don't quite work and so sometimes you manage how much you worry about them. It's certainly hard to get everything right and the weather plays a big part in that. You can make all the plans in the world and the weather changes and they're all thrown out the window. Weed and disease control is always very easy with hindsight and knowing when the perfect time to go drilling was, or that it wasn't going to rain for another week and you could have held off and got another flush of black grass or flush of weeds. There’s always one where it goes wrong occasionally and you often don't see your mistakes until about six months after you did them.

Caroline: Fergus, farmers are under real financial pressure. Is IPM actually cost effective or does it require a long-term leap of faith?

Fergus: That's a good question. I'm probably not the correct person to ask, being organic, but I would say that every time we go in with a sprayer or we put any kind of controls in place, that creates a cost. But if you don't know the mistake until you've made it or it's six months or a week later and you say I won't go and put on that biological control, or  that insecticide, but you don't know whether that's going to pay off until you harvest the crop. It might mean that you lose a crop or you think it's a risk management game that you've got to work out is it worth doing. And with SFI, all the organic farm is down at IPM4. We don't spray at all for the organic regulations. We do use some of the companion crops, which is IPM3 companion cropping. And we have done some of that in the past and it has worked. But organically, in most fields there's not just the crop growing, there's a plethora of weeds, even though we use mechanical weeding in our fields. 

I think it's a very individual farm decision as to whether they're going to, and you also have to look at the local environment. It might be that the pressures where Chris is are different to where I am. Our decisions are going to be totally different because it's based on your soil type, weather, environment and as Chris said, it might be raining where he is now and it's sunny where I am. And it might be that the decision today was the right decision, but tomorrow it's the wrong one.

Caroline: Chris, if you were speaking to a farmer who is curious about IPM but hasn't taken the plunge yet, what would your advice be?

Chris: Definitely look at planning tools. It just helps you get a bit of structure into what you're doing. I think most people would probably find that they're already doing more than they realise. Every decision they've probably made up to that point or their agronomist has made would have some basis of IPM behind it, whether that's monitoring thresholds, or as Fergus just said, a sort of a risk management profile on these things. There's a lot going on in the background that farmers perhaps haven't even thought about as part of IPM. But definitely have a look at some of these tools and get some thoughts down on paper and how it fits in around the farm and what you can do to improve it.

Caroline: And Fergus, where do you see your farm's IPM journey going from here?

Fergus: That's a good question. When Charlotte visited she brought the samples and she would point out the various insects. It sparked a curiosity to learn more about insect life. And also what we're looking to do in terms of cover crops, what can we plant, maybe divide the field up using strips or something that might allow insects to move more freely around the farm. And coming around to the conclusion that we probably could be trying to use insects to actually benefit the crops we grow. As much as we're trying to remove the bad ones, maybe let's also try and encourage the good ones. That will create more of a natural balance that will reduce the need for the use of insect controls or pesticides through actually building a natural diversity without compromising on the area of land that we use to grow crops on, as it’s also very important that the fields are productive.

Caroline: That was a really interesting conversation. Thank you so much to Sam, Charlotte, Chris and Fergus. It's been a genuinely fascinating conversation and it's brilliant to hear how research and practical farming experience are coming together to drive this forward.

For anyone who wants to find out more, visit gov.uk and search for integrated pest management guidance, where you'll find practical tools, planning support, and links to external resources, including IPM Net, a free knowledge sharing network run by the Yield Enhancement Network. The ADAS and SRUC IPM planning tool is also well worth exploring if you want structured support for building or reviewing your IPM plan.

If you're interested in funding, the Sustainable Farming Incentive has actions that support IPM and the Farming Innovation Programme and Accelerating Development of Practices and Technologies Fund and ADOPT scheme are also worth exploring.

If you enjoyed today's episode, please do subscribe and share it with other farmers or anyone with an interest in sustainable agriculture. And if you have thoughts on IPM or topics you'd like us to cover in future episodes, we'd love to hear from you. Until next time, thank you very much for listening.

Additional links:

 Rothamsted website:Rothamsted Research: Advancing Sustainable Agriculture.

The Rothamsted Insect Survey which provides Aphid Bulletins so farmers can have alters about migrating aphids coming into their crops that may help monitoring decisions and plant virus management: The Insect Survey | Rothamsted Research