Entomology, Integrated Pest Management, Plant Pathology, Weed Science

Episode 16: Integrated Pest Management Discussion

Join Emily as she talks to Jeff, Nevin, and Bob about how IPM influences their disciplines of study.

This transcript has been edited for clarity. 

0:19 Emily: Hi everyone and welcome to Farm Sci-Ed,
the show where we go into the science and education behind farming. I’m Emily Stine, and today we’re talking to Jeff, Nevin, and Bob about IPM and how it interacts between their disciplines.

0:45 This will be a two-part episode, so stay tuned for the next one after this. So Jeff, Nevin and Bob, can you explain the – the core tenets of IPM and how that works within your disciplines and as a whole?

0:57 Jeff: So thinking about integrated pest management and a brief overview from an entomological perspective, that’s that’s where the original idea of integrated pest management originated was. As we talked about in previous episodes, some of the early work in the late 40s and early 50s by entomologists in California were looking at, trying to find ways to integrate ecological aspects of insect pests, biological aspects of insect pests, and their management together into more of a unified principle, which then eventually evolved into developing economic decisions into those those basic principles of IPM as well that they developed over time. And so as a discipline, generally we use insect numbers as a proxy measure to determine the injury potential of a given crop to a particular insect species, and then we use those numbers to make a decision as to whether or not we should be concerned about resulting injury – that it would be economically damaging or not. As we talked about before, if it’s going to reach an economic injury level, or or exceed it and then use those economic parameters that are incorporating insect numbers to make recommendations for producers or land managers.

2:28 Bob: Well a lot of it I think is your your definition of integrated pest management, but for me it’s where you’re using multiple sources of – like for example – to manage a disease, you’re not the uh you’re not just just sticking with one particular one, depending on one, you’re looking at an integration of multiple different isolates, or multiple different forms of management. One of – one of the examples I guess, would be the combination of genetic resistance and fungicides. Say in in a cercospora leaf spot so that’s that’s one, one particular uh example of that so it’s it’s integration of several different methods of management for a disease.

3:18 Nevin: So uh in weed, weed management you can’t really – you can like in rangeland situations, or or natural areas or when you have an invasive pest, like you can scout for those, but in an agronomic field you can’t really scout for weeds. um They’re going to emerge as soon as the crop emerges, and you know generally preceding the crop, you’re going to be winter time. So it’s very difficult to scout for weeds, so we don’t really do a weed scouting system like they would do with an entomology. And the other thing with with weeds is except for extremely rare cases, the number of weeds present in the field is always enough to cause an economic injury. And so there’s never going to be a situation where you just don’t control the weeds, so we can’t really uh scout and we can’t really, uh it’s very difficult to model um you know should you or should you not do any weed control. So you’re definitely gonna be doing weed control. So with integrated weed management, that it really is just using as many uh practices as as possible, or as needed with the goal of reducing herbicide use. So the idea is not to reduce weed control, it’s to reduce herbicide use. And that’s sort of what defines integrated weed management.

4:30 Jeff: So each of us talked about, well Bob and Nevin talked more about the – basically what we had talked about previously is the pillars of IPM, so we talked about the foundational principles which are eco ecological basis, you know the scientific basis for uh for IPM and then you have these pillars, which are the tools, tactics, and strategies that we use to to manage pests and pathogens or weeds. um You know, Nevin pointed out that, you know, in weed management it’s it’s pretty specialized, you don’t really scout for weeds – um not that you necessarily can’t – but if you did, you’d be too late.

Nevin: yeah and so and that’s what you when we do, we do scout – and you should absolutely scout – but it’s kind of uh it’s kind of a post-application scouting, so it’s not um you know if you’re walking the field before an herbicide application and trying to see like what’s up, um you know, you might have already missed the boat at that point. It might be too late. So uh it’s usually to see what failed from that that application, not to make it.

5:33 Bob: You’ve also got to remember that if you’re looking at a monocot or a dicot, you have different herbicides that if you mistakenly identify one of them, then using the wrong herbicide is going to cost you even more – You’re paying double.

5:47 Nevin: – and that’s that’s true, I mean good ID is important but for for most farmers, you’re going to have four or five peak weeds in that field, and you’ve been dealing with them for the last 20 years. So you know what’s in the field for the most part, let’s say new comes up and that’s why it’s it’s more of a “did this work? What went wrong? How can we fix it next year’s?” sort of approach to scouting unlike you know for – I think both of you use thresholds for your calculations, for many of them right?

6: 13 Jeff: not in every case you know um for a lot of our
our bt corn traits we don’t necessarily scout and make a decision before the season starts as to whether or not we’re going to use that that given tool or tactic for its management. And so, from that perspective, for insect management it is very similar to weed management growers making the decision, you know probably the year before and buying the corn as to whether or not they need a corn resistant trait or a lepidopteran trait in the corn and then planting it really just based on field history which actually is pretty similar to weed management.

Nevin: yeah.

Jeff: You make decisions based on field history not necessarily within the season.

6:52 Bob: Well, same thing with us with the root pathogens or soil-borne pathogens. You know, you know those things aren’t going anywhere. In certain fields, you may have uh running to run into several different problems that are not going to go away. And so you need to remember that the next time that that field is cropped.
Jeff: But you know, both us and plant pathology you know do have some advantages for those insect pests, where you know we we can determine either through forecasting that you might use for a certain plant disease or as an insect, you know maybe it doesn’t develop every year, but you have, it’s you know Bob: it’s not always, not always too late.

Jeff: Right yeah.

Bob : Sometimes it could be, but it’s not like the situation where you ‘re already too late.

7:37 Jeff: Where you may be able to zoom in at a particular time of the season, where you may not have to treat every year. And in the case, I think with weeds as well timing is important in terms of growth stage and

Nevin: absolutely

Jeff: things that weed scientists think a lot about in terms of the appropriate timing of the application that herbicide relative to the
physiology of the plant.

Nevin: And sometimes, we get tangled up in there. So a lot of dry beans, for example, it might not be the best time to spray an insecticide but it’s the right time to put a post-emergent herbicide in so the farmer’s going to compromise on one of those and might not be getting all the benefit or even any benefit for controlling one of those pests. And so sometimes we contradict each other as well.

8:19 Jeff: Same goes for some of the, I think – fungicides or bactericides they might tank mix um along with an insecticide, I don’t know if that happens so much with herbicides but certainly certainly uh insecticide early insecticide cocktails are not unknown, um and you you see that with seed treatments as well. They’ll try to um there are build multiple methods and strategies for you know, coating a seed with an insecticide packaged along with early season fungicide. Again a lot of those decisions I think are based on um most optimistic – most optimistically are based on field history, right, but sometimes they’re cultural decisions as well.

9:05 Emily: We’ll be continuing this talk in the next episode, asking if IPM is sustainable and their general thoughts on the topic.

Join us next time, as we continue discussing integrated pest management strategies and whether or not we think it can be sustainable. Be sure to subscribe to this channel, follow us on twitter @TheFarmSciEd or visit our website at farmsci-ed.com for transcripts and other episodes. Have a good one!

Entomology, Integrated Pest Management

Episode 13: Integrated Pest Management in Entomology

Join Emily as she talks to Jeff about how Integrated Pest Management (IPM) evolved from the entomology concept of “Insect Pest Management”, and what concepts are often used in making IPM related decisions.

This transcript has been edited for clarity.

0:19 Emily: Hi everyone and welcome back to an episode of Farm Sci-Ed, the show where we go into the science and education behind farming. I’m Emily Stine and today we’re taking a bit of a deviation from our discussions about specific research projects. Instead, over the next couple of episodes, we’ll be talking to Jeff, Nevin and Bob about integrated pest management and why it matters to their specific disciplines.

0:40 Today, we’re speaking to Jeff about the general concepts of IPM and how they apply to insect management. So Jeff, can you explain what the three pillars of pest management are?

Jeff: So pillars of pest management is a reference to Dr. Larry Pedego, who was not the founder of integrated pest management, but definitely one of the key proponents, particularly in the 70s of integrated pest management and and beyond, where he uses a bridge to illustrate the components of what make up integrated pest management. So in his model, the the pillars really represent um the different tools, tactics, and strategies that one can use to manage a pest, which are then built upon foundations of biology, ecology and really the science that feeds into those tools, tactics, and strategies.

1:42 E: And how is integrated pest management ecologically important?

J: Really, ecology is important for integrated pest management. Integrated pest management isn’t possible without a fundamental understanding of the ecology and biology of the pests on which you’re you’re targeting.

And so that forms the basis and the foundation that gives you an understanding of when I say ecology and biology I’m really referencing the seasonality of pests. So when does it occur throughout the season? How does it disperse throughout a field? What is its normal distribution or dispersal pattern in a given field? Does it migrate? Does it overwinter? What are the various life stages, and how long does it stay in a given life stage? What are the birth rates? What’s the normal mortality rate for a given insect or pest in general?

And so those different ecological aspects or really characteristics of of a population, is all information you can use to exploit with those various pillars of of pest management, so you can understand the timing better of when you know an insecticide or a cultural control tool might be used in the field that would basically take advantage of what you might see as an achilles heel so to speak for a given given a given pest species. And then in the framework of integrated pest management, how could you use more than one of those pillars how could we use more than one tool tactic or strategy in concert to develop a more robust resilient long-term pest management strategy.

3:30 E: How do economics factor into making IPM decisions?

J: Yeah, so we talked a lot about ecology and biology, but economics are the third part of that really important equation as to what makes integrated pest management a durable solution, you could say.

So in integrated pest management and particularly for for insect pests, maybe specifically in some pathogens as well, we can state that explicitly in a formula of cost divided by value times injury or damage times a constant or percent control expected from a given control tool or tactic. So that’s kind of wordy, but we have a very explicit formula that we can use that derives basically helps us understand an economic injury level. So for what unit of injury that a that an insect can cause to a plant, the relationship between that injury and the ultimate damage that’s caused to the plant through our research that we do, we can we can understand that relationship and we can extract that condense that really down into that EIL – economic injury level formula.

So that’s where economics fits into it at least from experimental standpoint, and it moves more into the practical as we then develop through research a better understanding on timing. So that we can develop thresholds that allow us to make a decision in the field with a tool or a tactic or strategy in a way that suppresses that that insect pest population before it ever reaches that economic injury level. And then that moves us into really the more operational aspect of integrated pest management, which is having an action threshold and then doing research on figuring out the most easily adoptable strategy for sampling to ultimately then make a decision that’s both convenient and easy and again durable for for that practitioner, grower, rancher, homeowner in some cases.

5:44 E: Can you explain how integrated pest management has evolved from insect pest management?

J: Yes in the late um really the late 1940s early 1950s um following World War II in the development of certain chemistries their um and before that time really their pest management generally was on a calendar basis uh maybe using something like farmer’s almanac or maybe more precise field history, but it was really more more of a calendar and experience based approach for for management. Once more tools became more convenient, tools like insecticides became more readily available, more diverse than what we had in the past, there became more issues with the pervasive use of those chemistries both from an environmental standpoint but really from an economic and ecological sustainability standpoint as well.

So some researchers in California had worked to develop this more economic based model which eventually became integrated pest management to try to incorporate economic factors into that decision making process, So it wasn’t just simply based on calendar or field history or experience but actually using insect numbers or some sort of proxy for plant injury to actually make a determination as to whether or not you need to spend money on an insecticide or whatever the tool or control strategy might be, because in some cases no treatment is the best option not only from the standpoint of maybe the insect – you know they may exist in low sub-economic numbers and may not need to be treated, but in some cases you have various conservation strategies or easements that can provide beneficial insects that you don’t want to reduce their numbers and maybe they’re substantial enough. And in some cases, we have economic thresholds that actually incorporate beneficial insects into that calculus as well, again helping growers make decisions that from an economic standpoint make the best sense.

8:02 E: Can you elaborate a bit more on what you mean when you say adoption of IPM practices?

J: When I talk about IPM adoption I’m really talking about incorporating an integrated pest management plan into one’s practice. And to do that, you need to know it well enough it needs to be convenient for your for your cropping system, for your for your program, that you’re working with and the the tools have to be have to make sense and have to be user friendly, if you will, for for the grower or or land manager.

So when I’m thinking about IPM adoption, I’m thinking about a couple things. At least is information about a given pest readily available? So is there an easy way for a grower or agriculturalist to access the information to even know what the tools are that are available for sampling a pass, to determining an action threshold, to knowing what the different tools are, whether it be pesticides or crop rotation strategies and whatnot.

And then the other part of it I think about are what are the scientific tools that are available, and are they convenient enough for our growers to use? Scientists like to science I guess, you can quote me on that. And so sometimes, our research papers aren’t very user friendly from a practitioner standpoint, and so more work needs to be done by perhaps people with Extension appointments that work with the Extension Service throughout the United States at our land grant universities like the University of Nebraska, can take that information and translate into a way that’s more user friendly for our growers.

So you might have a threshold that I don’t know might use some tools or some counting that actually takes a lot more time and money just to derive the information than to just make the treatment. um And so you know in some cases then more research actually is needed on finding more convenient tools to have maybe lower threshold numbers that you can use to infer how the population is developing or even using convenient shortcuts, tools that anyone might have on hand. Some cases I’ve seen thresholds for things like soybean aphids in the past and using like a quarter from your pocket to estimate, to give you a sampling area for the number of aphids that might be on a plant. Different kind of shortcut methodologies like that making it easier for decision makers to make a decision or shortening the amount of time it takes for decision maker to come to a decision, whether that decision is the treat or not treat or hey I need to come back in another week and sample more insects because I – there aren’t enough here to really make a concrete confident up or down decision on yet.

So yeah I think about all those things when I think about IPM adoption, but at the end of the day I’m really just thinking about how do we make the decision tools that we have available and the management tools that we have to available, After we make those decisions more convenient for people to use and sometimes it you know convenience is also a matter of crop value so whether that crop value is high or low your tolerance for spending more time scouting or using a given tool might change from year to year depending on that that market. So I think bringing all that together in in context is really what I think about about IPM adoption and then ultimately if we can have a suite, a strategy for IPM for a given pest and it’s reliably convenient to deploy for sampling has a robust solution of maybe multiple tools or tactics for management. So we’ve got different options for a manager to make a decision with then becomes part of the culture and becomes the way that you manage specific pest using various tools and tactics that you might use. And so then ultimately adoption is a matter of culture becomes part of the culture and practice of of how you deploy a pest management strategy against a given species.

12:19 E: So folks, today we started a new section of Farm Sci-Ed, where we talk about the science and education behind integrated pest management.

We started talking with Jeff about what the three pillars of pest management are and how they factor into integrated pest management. We also discussed how entomology and insect pest management gave way to the current integrated pest management practices. Join us next time as we talk to Nevin and Bob about their respective disciplines and what integrated pest management means to them. Find us on twitter @TheFarmSciEd

and on our website at farmsci-ed.com for transcripts and more details. Have a good one!

Entomology, Integrated Pest Management, Plant Pathology, Weed Science

Episode 12: August Field Update

Join Emily as she talks to Jeff, Nevin, and Bob about their research project updates.

Transcript has been edited slightly for clarity.

0:19 Emily: Hi everyone, and welcome to Farm Sci-Ed, the show where we go into the science and education behind farming. I’m Emily Stine and today we’ll be talking to Jeff, Nevin, and Bob about what’s been going on in their fields over the course of the last month of August. So sit back, relax, and let’s go find out what they’ve been up to.

0:36 So Jeff how has your research been going?

Jeff: Well, in August in our relay study, we’ve continued to sample all the plots with the exception of the wheat only plot, as the wheat’s gone. So our continuing sampling has been primarily in the bean only and a relay treatments.

And so with that, as I mentioned previously, we’ve had some some challenges with the study that are related to these being research plots and the challenges of shared equipment related to that and timing of everything. So timing in this relay system, particularly for herbicides is important. And that post post-harvest operation of the wheat in the relay system, it’s pretty critical to get that post herbicide application on, but we have to wait for the wheat to be harvested before we can get that application out there.

So that relates to our time in August because we can see in some of those relay plots, the the weed – the weed escapes as a result of us not being as timely as we would like to in these research plots anyway to get herbicides on. So other approaches we could have taken with the research was if we would have had smaller plots we could have used a sickle bar to cut the wheat and then maybe hand harvested the wheat but our plots are quite large – 40 by 40 feet – so that wasn’t really viable option for us um and we don’t have a 40-foot sickle bar so totally out of the question but because we were using a combine, trying to simulate that at least on a small scale. We were waiting for the equipment to become available, so we weren’t able to be as timely as we would like.

But we are continuing the sample as I mentioned earlier for for insects. We had one more sampling time of of different sample types and we talked about that before; sticky cards, vacuum samples, pitfall samples, we give those another opportunity for catch in August. And now we’re basically watching the beans turn yellow, so senescence – maturity of the beans seems to be a little earlier this year, and we can see that also in commercial fields in the area. Some of the beans that got in a little earlier, particularly around the hay springs area in Nebraska are already cutting and so our research plots are following suit. They’re turning yellow and it seems like the dry beans that are in the relay treatments – uh i think we observed this last year as well – are a little bit later in the maturity timing relative to the bean only.

So if you’re out looking at our plots, you’d see the bean only plots would be pretty yellow and the pods are starting to dry down, in our relay study you might even still find some flowers out there. So quite a bit of delay in the timing, and that’s related to shade and some other factors that will be one of the many things that we’ll have to tease out and work around because delayed maturity in beans is not a desirable trait to have in a cropping system, particularly for dry beans. You ideally want to get them harvested as early as you can, but just part of the research and why we’re looking at those things.

3:54 E: And Nevin, how about yours?

Nevin: Well, August is kind of – at least for dry edible bean research and weed science – August is probably our slow month. Which is, which is nice because it’s going to get real busy real quick.

um So all of our treatments have been put out now, we’re kind of slowing down on our assessments as well. And so we’re just really maintaining plots right now and just sort of making observations. So a couple things that are happening: the dried beans are starting to turn, so uh this time of year as we get close to harvest, they start to get yellow and it’s it’s actually pretty interesting. If you’ve got a field where you’re not having any sort of pest pressure or irregular watering or anything like that or everything’s uh pretty uniform as far as your inputs go, you can you can start to pick out differences in um soil uh texture because you’re gonna see certain parts of the field which maybe have a different uh coarser texture, more sandy, not as much water holding capacity, potentially those are gonna start turning yellow a little bit quicker and so we’re starting to see that. We’re starting to see these patterns in the field where some parts of the field are turning yellow, some parts aren’t but those do actually occasionally line up with with weed control treatments as well.

So we had a couple, we had one experiment this year where we were applying a bunch of different soybean herbicides that are not labeled in dry edible bean, but we’re trying to see if there’s potential to expand a soybean label and a soybean herbicide into dry edible beans. And we’re seeing some delayed maturity from some of those treatments now that delayed maturity likely is not going to result in the yield impact but we’re going to find out but some of the plots that are now quite yellow, right next to it, they’re they’re still in the midst of flowering. And so there’s, there’s pretty noticeable differences between some treatments and so that’s sort of, just what we’re seeing now, um we’re making notes of that,. But that’s going to get teased out when we go for for yield so we’ll know what the moisture content is of those beans and that’s going to give us a comparison of of what the maturity is at that time of the year.

5:54 E: And Bob, how about you?

Bob: Well, there hasn’t been a lot of disease from any anywhere in our in our plots. We did find a few lesions um periodically, but not enough to to uh need a application of the fungicides for for a grower.

But because of the studies that we are doing, we’re trying, we will go ahead and spray; either if it’s not this afternoon, then we’re going to spray tomorrow just to test the treatments that we said we were going to use. And then um just see what happens, even though the disease has not been um has been formed in our plots very readily. And but and I still don’t understand why, but it has not done that. But it is it – but it is present, I guess. and the spore catcher thing that we were trying to use – the spornado – has never told us that has – never detected any spores. So that would be with the disease triangle, that would be one of those uh points that were taken off. Which is then what we want to do to, to to manage that and they have not been conducive for the the disease to occur to a great extent. Although we have found a few here and there.

7:04 E: Well folks, there you have it. Today we talked to Jeff, Nevin, and Bob about where their research projects are at and what’s been going on in their fields over the month of August.

Stay tuned as we continue to delve into the science and education behind farming in plant pathology, entomology, and weed science. Follow us on Twitter @TheFarmSciEd and visit our website at farmsci-ed.com for transcripts and more updates. Have a good one!

Entomology, Integrated Pest Management

Episode 10: Insect Sampling and Collection

Jeff talks with Emily about insect sampling and collection for his entomology studies.

This transcript has been edited slightly for clarity.

0:23 Emily: Hi everyone, and welcome to Farm Sci-Ed, the show where we go into the science and education behind farming. I’m Emily Stine and today we’ll be talking to Dr. Jeff Bradshaw about entomology sample collecting and the different processes he uses to get samples. So sit back, relax, and let’s go see what Jeff uses in the field.

0:42 So Jeff, can you explain the importance of sampling to entomological research?

Jeff: Insect sampling in general has a couple purposes, when it comes to pest management at least and some other disciplines as well, but there’s sampling for research essentially, and then there’s sampling to make a decision as in applied field crop pest management, and then sometimes you’re doing sampling for research for the purpose of making the decision. So the reason that’s important is there’s different levels of intensity of sampling that you might use, depending on if you’re a crop consultant and you’re trying to you know make efficient use of your time and not spend a bunch of time in the field sampling, you just need to make a decision at some level that you’re comfortable at versus when you’re doing sampling as a researcher – as a scientist – and you’re trying to use that data for other purposes, to learn more about the insect, when it occurs, how to control it at a high level of accuracy and precision.

So um sampling then for our study and for anything is one. There’s different tools that we use for sampling and then the purpose of the sampling. In our case, we’re collecting a number of different species and then using that sample to identify which species are present and then how many of those species are present within the sample.

2:06 E: What are the differences between sampling types?

J: Yeah so one other difference uh between sampling methods as I mentioned earlier: sampling for research or sampling for a decision. A lot of times we’re doing sampling for research, we’re using more than one tool. Basically attack a problem – if you will – from more than one angle, which is very common in science. Use more than one kind of method that you’re asking for, which you’re addressing, the same question because every sampling technique and tool has a slightly different bias, maybe towards different species or towards different catch efficiencies. Yeah, really what you want to do for research is you want to capture – kind of encapsulate all the different methods that you can, to try to see well, at the end of the day, if you have more than one sampling methodology or tool that you’re using, and they all kind of point in the same direction ultimately with their data, in terms of the conclusions that you can make, then you have a much more powerful conclusion because you have more than one method that you use to to arrive at it.

3:05 E: What do some of these methods look like?

J: Some of the methods that we’re using – specifically to our study – are vacuum sampling. So we have a leaf blower, which we put on the intake side of the leaf blower to use as a sucking tool and uh we cover the end with a mesh, and then move for a certain – well there’s different ways you can do it – you can move through a canopy for a certain period of time or certain distance or a combination thereof, so you have a standardized way of collecting with that tool. And so it sucks everything into the mesh and then you close the mesh around the around the sample and then put it into a plastic bag. So we’ve got vacuum sampler, got a sweep net that we use kind of similar type of sampling, you’re sampling the canopy of the plant just like you are with a with a vacuum sampler.

We have sticky cards that we leave out for a period of time and we’re targeting aphids or minute pirate bugs, aerial insects that are moving through the air and some of which are attracted to that yellow color color of this yellow sticky card. Then we use pitfall traps to ensnare organisms that are running across the soil. So essentially it’s a little more fancy than that, but it’s essentially a hole in the ground um and then the insects fall into the jar that’s within the hole and then we can pull the sample out of that.

And then we have pheromone traps that we use and those are much more specific. In this case, we’re using a pheromone to target the the pest of preference, in this case western cutworm and to trap them and to use that as just a general sampling tool to try to understand what their numbers are. And then a black light trap that we use again for for sampling purposes, and our purpose black light trap is really we’re trying to collect egg masses ultimately um from the western cutworms that are being attracted to that black light trap. And then other – you know – all those sampling tools are looking at ways to capture and then ultimately identify and count the specimens that are the species or organisms and numbers of organisms that are within the plot.

But we also have tools that we use to sample function, different tools that we use to sample function would be like sentinel prey. So we might use sentinel egg masses – so for example with a black light trap, we sample adults and then we go into the black light trap and we gather the females in the trap – well actually, gather all the western cutworms that are present in the black light, drop and then release them into a cage with corn or dry beans um and then give them 24 hours to lay eggs.

And we use those eggs that they lay on the dry bean leaves or on whole plants and we put those out into the field and then measure over a 24 hour period how many eggs are gone. You can put the eggs underneath the microscope and determine whether or not they’ve been sucked dry by a piercing insect or whether they’ve been chewed off by a chewing insect. And so that gives you just greater insight, not only the predation but maybe the type of predators that would be present and so that would sample the insects that are moving through the canopy of the plant.

Another layer of sampling would be to functionally sample the insects that are on soil – that we would use wax worms sometimes affectionately referred to as “truffles.” The way we lay out – basically clay um modeling clay with a pin that we attach the uh the wax worm to and then we leave it for a period of time, sometimes overnight, and then just we’ll have them in open cages and closed cages to expose them to the predation within individual plots. And then again, the the the data it will glean from that would be – you know – is the waxworm after 24 hours alive or dead? Is it still present? Has something ripped it off of the the pin and carried it off? um Has a piercing insect attacked it again? You can gain all those insights by – you know – kind of studying the specimen that you left, the sentinel prey that you left out with a microscope.

7:37 E: And what do you do with the samples after you’ve collected them?

J: All these different sampling methods whether we’re sampling for counts or sampling for function um take a lot of time. When we’re we’re sampling for individuals, like with the sticky cards or vacuum sample, you end up with a collection of individuals and so you have to go through the sample and identify the specimens that are there. Typically you’re not necessarily looking for everything that’s in the sample – sometimes you’re targeting specific groups or maybe specific orders.

And then at some point, you’re making educated estimate on which of those species might have high enough counts to give you some measurable differences when you start comparing treatments that is. If you have an extremely rare thing that only occurs in one sample, and it’s like one species of something that you’re you’ve rarely ever seen the sample, well, when you look at the data you’re going to have one and then a bunch of zeros and you can’t do anything with that comparatively. Whereas you may have a group – like when we’re sampling um for pitfall samples for example – again you have a bunch of insects in that sample, we know from prior research and prior soil sampling type work that ground beetles are typically have a lot of species or you can capture a lot of species with that method. And so that that family of beetles we might look specifically for and identify them to species, because we we think that that could tell us more, because we have more data associated with – this has more species or the species change between plots, where the numbers of individual species change between plot can then tell you something about either the habitat or the growth form of the canopy and different things different insights you can glean from that.

So when we collect them, they’re generally dead or we freeze them and make them dead. But generally we’re looking we’re looking at dead insects that we’re then counting. Sometimes on the sticky cards they might not be. The only sampling methods that we’re using where we’re actually looking at live insects are with the black-like trap sampling and again we’re we’re looking to keep them alive, so that the female moths can lay eggs and the eggs are alive. And so the sentinel eggs that we put out are living eggs, they’re not frozen so they they would be viable enough that they could even hatch within the plots and that again can give us some insight about that treatment and whether or not it had enough predators to kill enough the eggs that the larvae don’t hatch versus plots where you didn’t see that predation, now you have an infestation of western cutworm larvae that can then injure injure the plots.

10:45 E: What is the intent of all this collecting?

J: Yeah, so you know first we sort through it and there may be specific groups that we’re targeting. Within those specific groups, we might um identify them further to species uh or maybe the genus only and then from there you end up with a large database for each plot. Typically we might have three, four, maybe sometimes five sampling periods, so you could take that sample and repeat it throughout the season so you can multiply the numbers even more. And so so our data sheet would look like certain numbers, certain numbers of individuals, a certain species by date.

And so what we then hope to learn from that or things that you can learn are how treatments might impact the occurrence across the season of certain species. So in our wheat relay, or wheat only, we might anticipate the presence of cereal aphids and we might anticipate that they might start out pretty low in the season and increase as the wheat grows, we have more and more of those aphids and then once we harvest the wheat, probably won’t see that many of those aphids anymore since they’re pretty specific to grasses, in some cases fairly specific to wheat and and closer associated grasses.

So um so then that relationship we see with the with the ebb and flow across the sampling dates of the aphids, we can then look at the data set that has our predators and see if they track along that same line and whether or not there’s any relationship between that seasonal change in aphid numbers and the predators that are present in the field to see if kind of one begets the other, in a sense. We look across the season, we see an increase in pests and then the predators track in association with that increase and then we harvest the wheat. And those um across the season we can see that those aphids now are no longer present, but maybe the um predators stick around and then we can start to see if then those predator numbers that have maybe stayed in those plots after the wheat’s gone shifted over to western bean cutworm, or if that changed the nature of the predation rate of the sentinel egg masses, or if it changed the predation rate as a result of our wax worm truffles.

So once you have the data, there’s different ways of looking at it, you know. We could look at the species diversity of the predators, and see if that changed. We could look at species numbers to see if that changed by treatment. Obviously you could see if the treatments had no impact on either those whatsoever. And then we could – we’ll also look at correlative items like relationships between prey and predator and if any of those relationships changed as a result of the treatment or not.

13:58 E: What are you hoping to learn from it?

J: Yeah, so once we have that data set and we look at those relationships, we can look at higher order relationships between those ecological functions that we were trying to measure – the individuals and and species diversity we’re trying to measure – and see if there’s if they track at all with the yield that is reported out from the plots or the injury that we see on those beans. And usually there’s um obviously there’s a lot of variables in the field, a lot of other variables contribute to yield and quality other than just the things that we’re measuring. So typically what we would do is constrain the conclusion that we’re trying to make, so we don’t overblow the conclusion. We can say, well, this proportion of the population can account for 30 percent of the yield increase or accounts for 10 percent of the damage that we saw. We can say it’s related to this relationship.

14:50 E: Well folks, there you have it. Today we talked to Dr. Jeff Bradshaw about entomology sampling and what he does with the samples he collects from the field.

Join us next time as we go into more depth on our other topics in plant pathology entomology and weed science. Follow us on Twitter @TheFarmSciEd, be sure to check out our website at farmsci-ed.com for transcripts and more information about this program. Have a good one!

Entomology, Integrated Pest Management, Plant Pathology, Weed Science

Episode 8: July Update

Join Emily as she checks in with Jeff, Nevin and Bob on what’s happened with their projects over the course of July.

This transcript has been edited for clarity.

00:21 Emily: Hi everyone, and welcome to Farm Sci-Ed, the show where we go into the science and education behind farming. I’m Emily Stine and today we’ll be talking to Jeff, Nevin and Bob to find out what’s been going on over the month of July. So sit back, relax, and let’s go see what they’ve been up to.

0:41 So Jeff, how has your relay study been going?

Jeff: A couple big things going on in July in the relay study. One is we harvested the wheat. And so we brought a plot combine in, and the other big item is that western bean cutworms are flying and so those numbers are ramping up now. We’re still right around 25% emergence based on our predictive model and uh presently we’re catching hundreds every night. So we’ve got quite a collection – a couple thousand – more than a couple thousand western bean cutworms in a cage, laying eggs that we’ll use for various things within the relay study.

E: Have you run into any specific complications this month?

J: So the wheat harvesting relay this year is a bit challenging. Partly because in our research program, we share a lot of equipment, particularly expensive equipment like plot combines. And so you kind of get the equipment when you get it and this year we got the equipment a little later than we would have liked to, which meant that the dry beans were a little further along in maturity than they would normally be. What that means, is the the plants were bushier, a little bit bigger and they were starting to bud, so the flowers were just starting to form.

And so normally, last year, for example, we were able to get the combine a little bit earlier prior to – prior to budding and before the beans really had a chance to um to bush out that much. So what that meant was a couple challenges. One major challenge was because of the uh increased kind of growth, morphology, structure of the dry bean plants, they were more prone to getting run over by the combine. They get caught by the wheel and and you can knock a row down here or there. Fortunately we have really large plots, um but one thing we did do, um not only because of that sort of – what you could call “combine blight,” uh but also because they – as I mentioned – were starting to bud, some of them may have been starting to flower. That’s a fairly sensitive time for a dry bean plant. It’s more susceptible to injury at that time, mainly because those flowers can drop off. If you lose a flower, then obviously you lose a pod. You lose pods, you lose str – lose beans and so you lose yield.

So what we what we decided to do is we ran the plot combine through all the plots, regardless of whether or not the plot had wheat in it or not, just to make sure that all the treatments were treated the same – had the same potential for combine blight, if you will. So that was one challenge. We were successful in harvesting wheat off the top of the beans, the bean canopy was starting to get kind of close to the top of the wheat and there were a couple plants here and there that we clipped, and in fact there were quite a few growers and agriculturalists on Twitter that were pretty interested in us evaluating the clipped rows from the unclipped rows; partly because there’s some interest in the dry bean community and other growers, other crops as well that have similar growth habits, to try to understand what that clipping does to yield. There’s a bit of a debate on whether or not if you clip a dry bean at a certain time of the year if that promotes more branching, which promotes more flowering, so on and so forth, so we’ll probably take a few additional notes to try to account for some of that.

The other challenge was because the beans were already flower flowering, and we had to wait for the wheat to be harvested out of the relay plot. Before we could spray our first post – our post herbicide application, we were not able to apply uh herbicide in the relay plots, because the dry beans had begun to flower by the time we got the wheat removed from those plots. So so those plots will be uh not be receiving a post herbicide application. Benefit is, um in in treatments or in plots that are the relay plots where they have this cereal in it – like I, I think mentioned before – is there’s pretty good weed suppression in those plots as opposed to the conventional beans which had no residue at all – had a lot more potential for for weed development. So so we think that’ll that’ll work out okay, um but might require a little bit of hand pulling here and there.

E: Gotcha, well I hope you get some good data out of it anyway.

5:37 And Nevin, what about you? What’s been going on for you in the month of July?

Nevin: Well, July has has sort of been a continuation of June. June got very hot very early. I wouldn’t say extraordinarily hot, but it usually doesn’t get as hot as it does that early. So we were hitting triple digit temperatures uh earlier than we usually do, and July has sort of been a big continuation of that. So it’s been a very hot year and in June uh when we were planting our dry edible beans, we had a number of herbicide failures. Mostly we first noticed with our pre-plant burn downs.

So we have a few trials that are going into a cover crop or no-till and the products we use to kill that cover crop or the weeds that are present in those no-till studies, they just weren’t working. And um that’s a common experience among a lot of the people in the area. I’ve got some – I’ve been talking to my stakeholders that work at different uh agricultural service companies, different co-ops, and they’ve been having a lot of reports of herbicide failures. So that happened in June, but what we’re seeing though, is that that those failures this year um has has extended into our our soil applied herbicides, which are really critical for dry edible bean control and um we just have not been getting very good control.

And that’s, that’s a good thing actually for research. It’s not a good thing for farmers but uh we’ve got a few studies where we’re comparing uh group 15 herbicides so we’ve got Outlook, Dual, um Warrant, some of those products are labeled and dried, some aren’t. So we’re trying to see if there might be some possibility to expand the options available in dry edible beans. And we’re starting to see some separation, those products now in a normal year we wouldn’t see that separation. Everything would work pretty well but I think this year with just that – the higher temperatures um and also the increased irrigation that we need to put on to keep up with those higher temperatures, we’re starting to see faster degradation of the soil applied herbicides and we’re getting a little bit more separation in our weed control results between treatments and that’s good. You want these years, so that in normal year maybe there wouldn’t be a big difference but these extraordinary years or sometimes when you learn something.

E: Now if I’m correct, July is the month you do most of your data collection, right?

N: Data collection is pretty much what we’re doing in July. At this point, especially right now, it’s a bit later in July. We we have in the first couple weeks of July, we have sometimes – some later post-emergent herbicide applications in dry edible bean, but then we’re basically done with imposing treatments for the year. So what we’re doing now is maintaining plots by scouting for diseases and insects, sort of those lesser pests and try and keep up with the irrigation. That’s basically what July is.

But on top of that, we have data collection and right now what we’re doing is: depending on the trial we’re going out every week, every two weeks and we’re taking assessments. So visual assessments, we’re looking at the plots and just kind of making a note saying this this controlled um let’s say 70 percent of the weeds compared to the non-treated check where we didn’t do anything while this other treatment uh we’re looking at 80% control. And to kind of bolster those those ratings which are done visually, we’re also going in and taking some physical data uh and that’s mostly right now in the form of weed counts. We’ll do some more other stuff later on.

So we’re putting out specific quadrats – there’s, there’s my here’s my quadrat right there – and uh those are are laid out in the field and more or less a random method within each plot so that we’re not biased by where we’re putting it in in the plot. And then what we do is we we just count every couple weeks how many weeds are in that plot. And that gives us an idea of if there’s a difference in species response to certain herbicide treatments or if we’re seeing different types of herbicides come up at different times of year. so we can kind of track emergence throughout the year and uh we’ll be doing more measurements later on as we get closer. But that that’s been mostly what we’ve been doing.

We also have to in in certain studies we have a – what we call a hand weeded check, so in order to assure that we have a plot that has zero weeds in it. And we need the zero weeds so we know what the yield potential is of the dry edible bean crop and or other crops in absence of weed competition. We have to maintain those plots weed free and sometimes the best way of doing that is just going out there with a hoe and so we spend a lot of time this time of year going out, usually in the morning before it gets too hot, and we’re with a hoe and bent over just pulling weeds. And that’s a lot of what weed science is.

E: Hope all that went smoothly for you.

10:34 And Bob, how’s your cercospora and sugar beet study going?

Bob: Well, they’re doing fine. From a standpoint of a pathologist, it’s kind of disappointing. There’s not a lot of disease out there. We did inoculate a couple weeks ago, and the Spore-nado thing that we’ve been using, which which measures active movement of spores if they’re present, has not – uh has been zero. We’ve done this now for the three weeks, and uh there’s been no um cercospora found on the on the little discs that we see. It’s been – it’s certainly been hot and it might have been a little bit too hot, but it’s been high moisture in terms of the humidity – it’s been brutal. And it’s certainly been hot enough for that, but it’s not there. There’s apparently not any spores flying around. So we went out, and looked at that again – I mean I looked at it every week.

If we go back to the disease triangle, what we’re doing with the spore-nado is that we’re measuring to see if the pathogen is present and with the alert system we were seeing if the environment was conducive, and it’s just been off the charts from from the different sites that we have. But the fact that we’re not identifying any spores takes away that leg of the – uh of the triangle. So that the pathogen is not present so we’re just not getting any disease currently, even though we’ve tried to do everything: create a more humid microclimate, and sprinkler – overhead irrigation, it’s just not there.

And I don’t – I can’t understand why, but for some reason, they – we haven’t had a lot of evidence that the inoculation did anything. I’ve seen weekly reports of of the different sites, and they’ve really been high, which would suggest that the conditions were conducive for for disease to occur. But I have not heard of any severe outbreaks, so I – I don’t know if if that’s the case or not. But it’s that’s – that’s what we have.

E: Fingers crossed you get the results you need.

12:39 Well, folks there you have it. We talked to Jeff, Nevin, and Bob, and checked in on all of their projects and what’s been happening over the month of July. Unfortunately they’ve all run into a couple of hiccups, but for the most part things seem to be doing okay. Join us next time as we continue going deeper in their projects to find out more specifics about how and why they do the research they do. Until next time, don’t forget to like this video, leave a comment below, and subscribe to our channel for more updates. Visit our website at farmsci-ed.com for transcripts of all the episodes. Follow us on twitter @TheFarmSciEd for more updates and reminders about what we have going on. See you next time!

Entomology, Integrated Pest Management

Episode 6: Biological Control in Relay Study

Join Emily as she talks to Dr. Jeff Bradshaw about biological control and what impacts that has in his dry edible bean and wheat relay study.

This transcript has been edited for clarity.

00:21 Emily: Hi everyone, and welcome to Farm Sci-Ed, the show where we go into the science and education behind farming. I’m Emily Stine and today we’re talking to entomologist Dr. Jeff Bradshaw about conservation biological control and entomology, specifically in his relay plot study. So sit back, relax, and let’s go find out all about this.

So Jeff, can you explain what biological control is?

00:46 Jeff: So biological control is a part of integrated pest management. So it’s a tool – a tactic if you will – that’s used along with a number of other tactics in integrated pest management to reduce pest numbers, regulate those populations in a different way. So an alternative approach sometimes in a compatible way with other approaches, tactics, tools that might be used for for pest management .

01:13 E: What kind of strategies are typically used within biological control?

J: So generally speaking, there’s kind of three strategies to biological control. There’s classical biological control, which historically has involved and focused more on invasive species where you have a non-native insect – a pest whether it’s a pest of ornamentals or crops or other situations that a pest might arise in – that are introduced into the non-native habitat to that particular insect. And then you – the classical approach would be to go to the location where it’s native for the in the pest – in the case of the pest – you’d go to a location where the pest is native. And you would study and seek out the the natural enemies and maybe the parasitoids that might be highly specific to that species. And then there are a number of approaches then to introduce that that parasitoid, for example, into that new environment to try to see seek opportunities for control of that non-native species. So a classical approach is really focused generally on invasive species and trying to import those regulatory – regulating organisms into the environment.

Now the other approaches – augmentative biological control is where you have some understanding of what the pest’s existing natural enemy complex might be and you are releasing another natural enemy – such as a parasitoid – to augment or to increase the mortality of that pest through adding more natural enemies into the environment. And then conservation biological control is where you’re using different strategies or tactics in the environment through maybe changing the cropping system, rotation strategy, or some strategy that you might be using in the landscape – certain plantings of flowers or woody habitat maybe – that would provide habitat for natural enemies to to survive the winter or survive when the pest isn’t around. So three kind of general tactics um strategies that are considered in biological control.

03:31 E: What are the specific focuses you have within your study?

J: So currently, we’re looking at – we’re focusing on kind of two different areas of biological control. We’re looking at augmentative biological control with parasitoid wasps that attack the western bean cutworm and then we’re also looking at conservation biological control, primarily within the field, and looking at different strategies that we could use in cropping production systems that would bolster natural enemy populations; again specifically to attack western bean cutworm.

04:07 E: What are the differences between cover crop and relay biological control?

J: Relay cropping is a type of cover cropping. The main difference is termination time. So we’re looking at this study, our hypothesis is that if we have crops growing – we have something growing in the field before our main cash crop – dry beans in this case – that that

that that crop can provide habitat to natural enemies. So like I mentioned earlier, that would be a conservation biological control approach, and the main difference and the hypothesis we’re looking at is that the length of time that we have a crop in the field, in this case winter wheat, prior to our cash crop, dry beans, that length of time will influence the natural enemy population that is then available for the control of western bean cutworm. So in the case of the cover crop, we’re using a cereal winter wheat and we’re – we terminated that in late May, early June

as opposed to the release – relay system which is also using winter wheat as the cover, if you will, but instead of terminating it in June, we’re allowing that wheat to senesce naturally so that it will dry down and become ripe in around now – first week of July and so we think – there’s a possibility anyway – that that timing of when that winter crop is either terminated or senesces

naturally, will have an influence on the abundance and ecological function of those natural enemies in that system.

05:52 E: Can you share some of the arthropods that you expect to see within these systems?

J: Yeah, so the cover or relay crop in this case – uh winter wheat – is uh is a cereal and as a cereal, it can be a host to a number of aphid species like the Russian wheat aphid for example, and typically, those while – those insects can be very numerous and be economic pests in their own right in wheat. Generally that’s not often the case, at least in recent years, but they’re always present, so those aphids can serve as a food source for natural enemies so those would be lacewings,
ladybird beetles, big-eyed bugs, a number of different chewing or sucking insects that are generalist natural enemies that might attack aphids. We know they have a fairly large diverse diet and so they will also go after other pests.

So in the case of dry beans, what we’re hoping is of course, those those aphids are cereal aphids so they don’t go – dry beans aren’t a host for those aphids. So that’s a key aspect in the system that that helps make it work. Obviously, if the aphids in the wheat were pests of dry beans then we’d be setting ourselves up to a pretty bad situation. But in this case, again, the aphids aren’t compatible with the dry beans, but the natural enemies that they attract in
the wheat will feed on western bean cutworm eggs or thrips, either of which could be pests in in dry beans.

So our hope then is that we’ll have a early season establishment. Some of those aphid species for example, over-winter in wheat and so those can be available as a food source for those natural enemies as soon as they finish overwintering and start to come out in the spring. So that should give a lot of time for those natural enemies to feed, lay eggs, and build up those natural populations over time. And again, we would – our question is – that those populations might build up to larger numbers because they’ll have more time to develop in the relay system as compared to the cover crop system, at least under our conditions and the way that we’re looking at the system here.

And so timing wise, then we’re really kind of focused on the western bean cutworm – because it is a key pest of dry beans and as soon as – pretty close to when wheat senesces and typically is harvested in first or second week of June in any given year. That’s also really close to when we typically start to see one to five percent emergence of western bean cutworm and that can fluctuate given the year and the – you know the temperatures – and how they accumulate over the season. But that’s that’s kind of our goal is to try to target those natural enemies flushing off the wheat in high numbers to be present to uh – basically munch on those Western cutworm eggs that are are laid in dry beans.

09:03 E: You went into some detail on conservation biological control within your study. Can you elaborate a little bit on the augmentative biological control aspect?

J: Yeah, so the other part of our study we’ve looked at is augmentative biological control using Trichogramma ostrinae as a parasitoid of western bean cutworm eggs. And it was originally introduced into the US through a classical biological control program against the European corn borer. So that was a non-native introduced pest many years ago. And the biological control lab at Cornell University looked at this particular parasitoid wasp as a potential biological control agent.

Through the years, there had been some research, some science done looking at – um – the ability for that particular wasp to attack a couple other pest groups and we had done some early work looking at whether or not it would –
it found western bean cutworm eggs to be suitable, and we confirmed that they did at least in a laboratory. And then we did some field releases a couple years back, in – in cages to try to see if – in the field to see if there was uh any hope that there – you know if we showed it in a laboratory, but what you find in a lab doesn’t necessarily translate to what you find in the field. So we did sort of a semi-caged design in the field and kind of showed that yeah, it was still compatible host – the western bean cutworm eggs to trichogramma wasps there. So for a couple years, for three years actually, we did large-scale field releases on commercial dry bean fields and we used sentinel egg masses and sticky cards over – in every case a 10 acre square to look at the dispersal and dispersion of those wasps as well as their ability to attack western bean cutworms over that very large area.

And we’re still working on analyzing those findings, but generally we found that it seems like Trichograma ostrinae doesn’t really like Western Nebraska that much. It seems to work really well on the east coast, whether it’s green peppers or potatoes or sweet corn but for reasons we’re still sort of kind of fine-tuning what the next hypothesis might be as to why they might not work as well. But right now, we think it has to do with the environment, the climate that we live in is quite a bit different than than the east coast. If you’re not familiar with western Nebraska, it’s a semi-arid environment and semi-arid is definitely not how you defined upper New York state. So we think that probably plays a part in the success and why we had fairly low, fairly low parasitism rates.

12:12 E: Awesome, thanks Jeff. Folks, today we talked to Dr. Jeff Bradshaw about biological control and the different methods they’re using within the relay plot study. Join us next time as we go into more methods in these studies. Be sure to like this video, comment below, and subscribe to our channel for more updates. Visit our website at farmsci-ed.com for more videos and transcripts. Follow us on Twitter @theFarmSciEd for more information and for catching up on all those things you may have missed. Have a good one!

Entomology, Integrated Pest Management, Plant Pathology, Weed Science

Episode 4: June Research Update

Rather than talking to a specific researcher this episode, we thought it would be neat to see what parts of their research happens in the spring through June. Come join Emily as she talks to Jeff, Nevin and Bob about what’s been happening in their plots already.

This transcript has been minorly edited for clarity.

00:18 Hi everyone, welcome back to Farm Sci-Ed, the show where we go into the science and education behind farming. I’m Emily Stine and today we’ll be taking a little different approach, talking to Jeff, Nevin, and Bob about their current research projects and where they’re at in the month of June.

00:34 So Jeff, how has the relay study progressed over the course of June?

Jeff: Well, the month of June has been unusually hot and dry. So, we were able to get some timely applications in the study done, so we were able to in early June – well actually early May I should say – we got the herbicide banding done for the relay plots. So our strategy this year was to use an herbicide banding technique to spray out the wheat in the relay to create small beds for the for the dry beans that we’d plant in the relay treatments. Basically, in 30 inch centers we have basically a five inch band of wheat – three to five inch band of wheat – that’s dead that creates a – basically after the wheat dies in a month’s time, when it’s it’s very dead, there’s just a band left behind of, of no wheat, nothing growing. So then that creates a seed bed for our beans.

1:28 So we planted the beans then on June 1st, so about a month later. We used a GPS tractor for both of those so they could be locked in exactly where we wanted to plant the beans, which was not outside the banded seed bed but actually into the seed bed. So it was a little bit of trickiness with the equipment to get that lined up just right, but using the same planter and having some high precision equipment helped out that process greatly. So we got the dry beans planted on June 1st and again, it’s been pretty hot, so those beans came up really quickly. So we had emergence on June 8th; so about a week later they started popping up through the ground and we began our sampling process around then. I should mention we also fertilized the beans right after planting. So, in any plot that had dry beans planted in it, we applied a fertilizer to help the beans out. So right at that time, we – we sampled.

2:38 So our sampling plan continues on a number of different techniques. So we took wheat head sample – or we took wheat heads, collected them in the vials and shook them in alcohol and we’ll use the alcohol extract to look for thrips, both good thrips and bad thrips, to see what – what’s – what’s going on in the wheat heads since they can be a source, particularly for thrips. And as we’ve talked about before, since thrips can both be a pest for dry beans or beneficial, it’s important to account for those. We also, in all of the plots in each treatment, we set up pitfalls – pitfall traps. So basically holes with a cylinder in the ground and a cup that we use to collect ground roaming, ground beetles, or rove beetles, or other beneficial insects that are commonly found at the soil level that are collected in pitfall samples. And then we also took vacuum samples; so if you can imagine a leaf blower on reverse, that’s basically how we took the – we take vacuum samples. So we basically put a nylon stocking on the end of a leaf blower and uh – put it on the suck end of the uh – the sucky end (very technical term there) of a leaf blower, the intake of a leaf blower and then use that for a controlled period of time to take a standard sample. And we pulled those vacuum samples out of bean rows and the wheat rows – obviously if it was wheat only, there were no beans to sample, if it was beans only, there was no wheat to sample. But even in the relay plots where we obviously have both beans growing now and wheat, we made a concerted effort to just try to sample just the bean rows and just the wheat in those, to see if there might happen to be a difference between what we are vacuum sampling within the bean rows themselves and the wheat even within that in that relay treatment overall. And then of course, we’ll compare those samples across the different treatments to see what we’ve got. Other sampling techniques that are going on right now are sticky card sampling – so we have little three by five yellow sticky cards that have a tangle trap on both sides that we suspend in the canopy, which is pretty low to the ground right now, so we keep little – kind of wide – mesh cages around the sticky cards to keep debris from blowing into the sticky cards, leaves and residue that might be on the ground since the canopy’s so low, particularly right now. That’s our approach to keeping large debris out. But then those yellow sticky cards, the yellow color is really attractive to aphids and thrips, as well as some beneficial insects like minute pirate bugs and such. So we use those yellow  cards as again yet another sampling technique. Many times when we’re sampling, we’re capturing the same insect with different techniques, but sometimes there are insects that are very specific to certain types of sampling techniques that you may or may not be aware of. So it’s good to use different tools – different sampling tools and strategies to just see if one of them works better than another to try to capture as much of the community as you can.

6:02 So basically right now, the past week, we’ve had um more than a couple days that have been in the high 90s to over 100 degrees with – um except for last night we had some cool weather and some rain that came through and that was that was pretty pleasant. But over the past week, we had some pretty high temperatures, very unusually high temperatures for June which isn’t unlike what a lot of the Midwest has experienced over this past month really is unusually high temperatures. So as a result, the wheat is finishing very aggressively, maturing along, and the beans are growing pretty aggressively as well. And also over the past month, we established soil sample soil sensors to establish soil moisture levels so we can try to keep on top of irrigation scheduling and so far that seems to be working, even though we don’t have really highly accurate soil sensors. They work well enough to just keep us out of the red. Last year we had some challenges, particularly in the relay plots not keeping up on enough soil moisture and so the beans would occasionally wilt. And you don’t want to get a crop to the point of wilting because that – sometimes you can wilt a little too much, and you actually lose plants as a result. So pleasantly, this June we’ve not seen any competition uh visually between the beans and the wheat. The wheat haven’t – the bean plants haven’t wilted due to the wheat competition.

7:42 E: Thanks so much for that update, it sounds like things are going really well out there. And Nevin, how has the first part of dry edible bean growing season gone?

Nevin: Well, dry beans are a pretty late planted crop in um well, everywhere, but the panhandle included. And the dry beans were planted last week in May, which is pretty typical. They’re usually planted towards the end of May, first part of – part of June and we we got all those in the ground by the – I think before June this year, which is pretty good for us. And there’s not actually too much going on at the moment as far as evaluating weed control. We have our pre-emergent herbicides we put on at the time of planting, or slightly before planting, or slightly after planting, and those usually give us between four to six weeks weeks of control and they’re still providing control now. Then, the date that we’re recording this is June 25th, so we’re still looking pretty good as far as weed control goes. So we haven’t done a whole lot as far as assessment and we’re not really seeing a lot of weed problems yet because those pre-emergent herbicides are still holding on.

8:52 E: Are there any specific tasks that you’ve been doing?

N: With the palmer density study, we have the palmer amaranth up and uh what we do is we went in  – when I say “we”, it’s the royal “we”. It’s actually my graduate student Joshua Miranda. But he went into the study and what we have is we have six different levels of palmer density and we just kind of wait for that palmer amaranth to naturally come up and they came up right after dry bean planting this year. There’s no herbicides applied in that trial, and then we took different colored zip ties for each different population level – so we’d have yellow for a certain population, level in red, or you know so forth – and put zip ties around all these little tiny palmer amaranth plants and they’re going to stay there all year and then Joshua goes in two to three times a week and hoes out every single other plant that emerges. So it’s a pretty time intensive trial and we have to wait until those, those palmer plants emerge before we can do anything. But luckily, they came up early so we already have the populations established in the palmer interference study. We’re just going to keep hand weeding it all summer long and that’s really all we have left to do with that one until harvest time.

10:00 E: Have you had any abnormal challenges that you’ve had to deal with this last month?

N: The only challenge we’ve had, we have one study looking at different populations and row spacings of dry edible beans. So we have – it’s a very large trial; four populations dry edible beans and four populations – uh four row spacings and all those different combinations and that study was last we had planted. It was about a week later than the others and right as the beans were emerging, we got I think three – about a third of a – third of an inch – which isn’t too much, but that came down in about less than 10 minutes and so that that really washed out a lot of soil and we’re still the process of assessing the stand from that study, but it looks like certain parts of certain plots may have experienced some stand wash.

10:53 E: I know Jeff previously mentioned that he’d been facing some challenges with the heat. Have you been seeing the same problems in your crops?

N: The beans do fine with the heat. the beans are very – as long as they have enough irrigation water, they tend to do very well with warm temperatures and that actually helps speed things along for us so uh weed development crop development um how fast we sort of get through the season a lot of times depends on how warm it is and so when we have plenty of irrigation water available and this, this year, it’s been a good year for that. And we have a lot of heat units, the season just kind of comes along a lot faster so this has been a pretty fast season because we’ve had some pretty warm temperatures in early June but nothing that’s got in the way of doing research yet.

E: Well, I hope everything comes up just fine and things keep going the way they need to be going.

11:43 How about you, Bob, what’s been happening for you the first part of the season?

Bob: Okay well, the project began uh in the latter part of April, where we put down the pre-emergence herbicide and then it was planted on the third of May and then it emerged roughly two weeks after that. Then just last week, the post-emergence herbicide was then incorporated and then we’ve again continued to irrigate every week at least once a week and then put down about a half an inch each time. The next step with this is we will be inoculating the plots in about two weeks. We got this inoculum last year from infected plants just all over, dried them and then we’ll crush them up, mix them with talcum powder and then just sprinkle that onto the heads or on into the foliage of these plants. And then we will begin hopefully to use the forecasting tools that we’ve had to begin the study to begin the monitoring or accessing the information that we need for for both the presence of the pathogen and the environment, which is what we’ll be predicting.

13:00 E: Have the abnormal June temperatures been a problem for you?

B: It – well, it hasn’t really affected it to to date. I mean we were able to get up a nice stand at this point, uh because it was also the post-emergence about a week after that, it was cultivated. So that has taken away a lot of the weeds and I
imagine we’ll – we’ll have – we’ll end up putting another application of uh herbicide down sometime in August, I’m guessing. But, but the, this – the heat lately has not really affected I don’t think the the sugar beets because this is a last, uh an older, a disease that occurs at the end of the season. So we’re not really concerned about it right now.

13:42 E: Okay. What are you doing in the upcoming months?

B: Hopefully, we’re just going to inoculate and and hope that will enhance the chance for disease to occur. And then we’ll keep irrigating, keep trying to keep it wet and and see if that won’t uh establish disease a lot quicker.

E: Great! I hope that goes smoothly for you.

14:04 Thanks everyone. Today we checked in with Jeff, Nevin, and Bob to see how they were doing in their research projects. All three of them have their crops in the ground, we’re waiting for things to come up, and we’re kind of in a holding pattern. We’ve experienced an abnormally warm June and so things are happening faster than we expect them to and for us right now, that’s alright. Tune in next time to find out more specifics about the research projects. Be sure to like this video, subscribe to our channel, and leave a comment down below. Visit our website at farmsci-ed.com for transcripts and for other episodes you may have missed.

See you next time, have a good one.

Entomology, Integrated Pest Management

Episode 2: Introduction to Wheat and Dry Bean Relay

Join Emily as she discusses the concept of a relay cropping system with Dr. Jeff Bradshaw.

00:20 Emily: Hi everyone, welcome to Farm Sci-ed; the show where we go into the science and education behind farming.
I’m Emily Stine and today I’ll be talking to Dr. Jeff Bradshaw, entomologist at the Panhandle Research and Extension Center. We’ll be discussing his research on the relay system that he’s been working on with wheat and dry edible beans. So sit back, relax, and let’s go check out what he’s been up to.

00:42 So Jeff, can you explain to me what a relay cropping system is?

Jeff: So a relay cropping system is a method of intercropping, where you have one crop that’s planted into an existing crop and particularly in our case we’re looking at a cereal – a winter cereal, winter wheat – and then we plant dry beans into it – a legume – in the spring.
So the existing crop is then harvested first.

So winter wheat would be harvested before dry beans and we’ll harvest that off the top of the dry bean canopy essentially, and then we’ll come back in September and harvest those dry beans.

So typically, in these situations, we have often times – a legume is planted into into a cereal crop where you see these types of relay crop inter-cropping systems and part of that is because of their different plants. They don’t share necessarily the same diseases or pests or even weed control technologies and strategies.

01:44 E: And how does this differ from a cover crop?

J: Yeah, it does share some similarities with the cover crop. Some of the benefits of a cover crop as the name implies, is to provide cover at a time of the year where there normally wouldn’t be right. As opposed to just bare ground, bare soil that would have the potential to blow or to lose moisture and lose some of the other benefits that that a cover crop can provide including weed competition. Basically um, by having that cover present, the way that the relay cropping system is different than a cover crop is that you’re actually running that that early crop out to harvest. So that makes it different. And then in our case there’s uh timing of the crop that coincides with some kind of key pest development throughout the the season, as well as provide some benefits to the natural enemies that are in the environment. So if we, for example, have that relay cropping system established early similar to a cover crop but then as it matures, those natural enemies that are conserved in that relay cropping system can then emigrate out of the – of that cereal and into the legumes at a time, in our case, that would hopefully coincide with when when pests become more active. And so now, those predators can be available to to attack those pests – that’s the strategy anyway.

3:12 E: So when you’re growing in a relay system
what compromises do you have to make ?

J: Yeah, so there certainly are compromises as there are um in many cases in agricultural actions. So there is the possibility of reduced yield, so we’ve got – you know – competition between the two crops on any given plot of land. When we’re looking at that that relay system so they compete for really all the inputs that go to making a plant grow. So there’s competition with water, soil moisture, for example, there’s competition for nutrients, competition with light, and so all those become a factor to consider in this relay cropping system that could be trade-offs that need to be explored. And so ultimately, what we’re doing is trying to look at what would the balance of those trade-offs be? And from a whole cropping system perspective, are the trade-offs worthwhile, because they bring some other benefit down the line, meet some other goals for for the land manager and the agriculturalist or the producer.

4:19 E: Are there other benefits the wheat and dry edible bean system provide?

J: Yeah, so initially when we thought about this particular cropping system in our conditions out here in western Nebraska, initially you know, as an entomologist, I have a – I have a bug bias, sorry to say. But uh sorry not sorry. So you know, I did think about some of these relationships that have been shown in the literature between – you know – in regards to having a crop present earlier in the season. As I mentioned earlier, how they can help establish natural enemies earlier than they would otherwise be established in the field, and making them available later in the season in higher numbers where they can be more functionally relevant. But importantly, we also thought about the production system and what some – you know – our grower is mostly concerned with yield: the amount of grain that’s that’s harvested off the field, and of course the quality of that grain. And so we did, in thinking through this, think about the production aspects first.

And then it sort of dawns on you, as you think about a little more. “Like “oh that’s kind of similar to this,” “oh there may be some other side benefits to that.” So um those would include and specifically elements we think about dry bean production here in this part of the world, there’s a lot of interest in upright beans – upright dry beans. And part of that interest is because you can use a direct harvest combine, you don’t need the the additional equipment or additional passes through a field that you would need with a prostrate bean that’s grown along the ground. Or you have to cut it and windrow it and then come out and pick it up. So there’s these benefits with this direct harvest in terms of equipment: streamlining equipment, streamlining time that a grower spends in the field harvesting the grain; the trade-off historically with direct harvest is some challenges related to getting the pods high enough off the ground. Get them high enough off the ground, where the cutter bar can actually harvest a majority of the grain. So typically, we’ve seen that there’s, there can be a lot of variability depending on equipment and production practice and soil topography and and so on that can uh interact with with yield loss. But we see somewhere around 10% yield loss in direct harvest beans that are just a matter of the mechanical harvest process.

So in a dry bean plant – in the upright morphology –
we still see a lot of the dry bean pods hang below the cutter bar. You know, less than two inches above the ground and might even touch the soil surface so what happens is as the combine goes through, the cutter bar goes through, it clips all those beans that then can’t be taken up into the combine. They just fall shattered to the ground. So one of the things we thought about in this intercropping relay system was the attributes of the plant to grow a bit taller when it detects infrared light from surrounding plants or has uh light competition. So a dry bean plant will grow taller, the inner nodes would be longer, and the thought is then, those pods would actually be higher above the ground. So that’s one other aspect that we’re looking at strictly on the agronomic production side of things to see okay now we’ve got pods that are higher of above the ground, so even though if we have these trade-offs with – as I mentioned before – soil moisture, or nutrients, or light, we may see the benefit of actually recovering more more yield because we have a taller bean.

8:04 E: What does your research look like this year?

J: Yeah, so our aspect of the relay study – so we’ve got uh – we’ve got a bug side and a weed side of the study that we’re doing. And so, on the bug side of things, we’re specifically looking at the relationship between – um – well we’ve got four treatments that we’re looking at: we’ve got dry beans only, so we actually rototilled the plot and then planted beans; so really low residue, maybe a very conventional historic type of of bean planting from the
perspective of soil management, I guess
you could say of residue management. We have the cover crop approach which is – you know – winter wheat terminated around flowering.

Really, the the wheat is terminated at bean planting, so we plant the beans and we terminate the wheat crops so basically by the time the beans come up the wheat’s dying back.

So that’s our cover crop. Then we have a wheat only, so we have plots that are just left as winter wheat they won’t have any beans to try to look at the the competition – the the wheat competition side of things from just the wheat alone. And then, of course, we’ve got our relay treatment where in that case, we created very small beds for the beans to plant in – within – in rows within the wheat. And then and then planted the beans.

9:28 E: And what are you specifically focusing on within entomology and the relay cropping system?

J: Yeah. So with these four treatments we’re looking at specifically biological control and conservation biocontrol. So right now we’re – we’ve got pitfall samples, pitfall traps that we’ve got out in each of these plots for these treatments looking at ground beetles and other arthropods that would be roaming across the ground that might be influenced by these different treatments. Specifically looking at beneficial insects in this case, so there may be one management approach that seems to increase the number of functional species groups that are important for weed seed consumption, or maybe they’re important for predation of of pests later in the season, so we’re looking at those samples.

We also have sticky card samples – sticky card traps – that we have in the field to capture any winged insects, whether they be pests or beneficial and so we’re going through those counting a lot of thrips and aphids and as well as beneficial insects like big eye bugs and so on. Then we’re also doing vacuum sampling to again capture all the arthropods – pests and beneficials – that are actually within the wheat rows but then also within the bean rows even within a treatment. So in our relay treatment for example, we’re taking vacuum samples of the bean rows and then adjacent to those also. So we’re tracking that. We’re also taking sweep depth samples and we’re counting those. And when I say we, I’m – I’m using the royal we – I’m talking about my student Jeff Cluever who’s actually doing a lot of the work, as well as a whole host of interns this summer that are are doing the hard work of being out in the field in these hot hot days. But we’re also taking flower samples from the wheat and flower samples from the dry beans when they start flowering and then later this year we’ll, we’ll collect yield of course. But then we’ll also check the beans for damage from western bean cutworms specifically.

So ultimately, kind of our target scenario in this case right now, western bean cutworm is the key pest of dry beans in this region, and so that’s sort of our target pest. As to whether or not we think the system is going to work or not from a bio control standpoint, in July, we’ll have sentinel egg masses that we put out into plots to try to estimate the rate of egg consumption by predators in these systems, to see if the different treatments – whether it’s a relay or whatever – to see what the differences are between these treatments, relative to western cutworm egg mass consumption. And then we would hope that would then translate to reduced injury in the dry beans and increased yield. And so coming back to what we talked about earlier about trade-offs, so our hope would be that we’d have a taller bean so we’d lose less yield and then because of the system that we’ve established, we would have more bio control. So we should see a higher quality bean and then historically, we’ve had to rely on chemical control means uh to manage western cutworm. So it’s a high bar, but um one bar we’ve got with this in terms of a goal post is to see if we could eliminate or significantly reduce insecticide input into the system so we may be able to replace that insecticide cost effectively with wheat seed costs and that wheat seed costs – one would hope within an ideal world – pay for itself with the grain that you collect off of the wheat crop. So sort of the production side of things, that’s kind of how we’re seeing it. We see these replacements and so ultimately, I know that we are anticipating we should see less dry bean yield in the relay system unless we fine tune it further as as the seasons go on but we would hope that we again have a higher quality bean and recover more of that yield and spend less money on on insect pest control.

13:37 E: Well folks, today we’ve talked to Dr. Jeff Bradshaw about his relay cropping system research, what some of those compromises to be made are, and what his research is specifically looking at within entomology.

Come join us next time on Farm Sci-Ed as we go into the science and education behind farming.
Be sure to like this video, subscribe, and follow us on twitter or on our website at farmsci-ed.com
for more science and education behind farming. Have a good one!

Entomology, Integrated Pest Management, Plant Pathology, Weed Science

Episode 0: Welcome to Farm Sci-Ed!

Episode 0: Welcome to Farm Sci-Ed!


[00:19] Welcome to Farm Sci-Ed, the show where we go into the science and education behind farming. Farm Sci-Ed is a behind-the-scenes look at integrated pest management research in the western panhandle of Nebraska.

[00:29] Over the course of the season we’ll explore studies focused on some of the common agricultural pests in our region. This season we have three research projects: a wheat and dry edible bean relay study looking at conservation ecology and biological control (entomology), a series of dry edible bean and palmer amaranth studies looking at plant interference and herbicide options (weed science), and the detection and refinement of a warning system for the sugar beet pathogen Cercospora (plant pathology).

[00:59] Come join us as we explore the research Jeff, Nevin, and Bob are doing in the panhandle of Nebraska and explore the significance of their studies.

[01:01] Subscribe, follow us on social media, and visit our website at farmsci-ed.com for more science and education behind farming.