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!

Integrated Pest Management, Plant Pathology

Episode 1: Cercospora Leaf Spot on Sugar Beets

Join Emily and Bob as they discuss the Cercospora leaf spot in sugar beets.

00:30 Emily: Hi everyone! Welcome to Farm Sci-Ed. My name is Emily Stine and today I’m interviewing plant pathologist Dr. Bob Harveson, who’s doing some really interesting work on cercospora in sugar beets. So sit back, relax, and let’s go learn.

00:43 Emily: So Bob, what are sugar beets?

Bob: Sugar beets are plants that are greatly a result of breeding. It was found that this particular beets – in general, fodder beets and other types of beets – had sucrose in them, which is the same product that is produced by sugar cane.

So it allowed temperate areas to produce sugar, which then enabled everybody to be able to – it made it more available to the general public. Because previously, it had all come out of the tropics – you know from the cane – and so it was exorbitantly expensive. So it’s a crop that they have bred to the general plant that they have now. So there are high, high levels of sucrose within that plant and it’s the same type of product that is by the totally unrelated sugar cane. Which is kind of odd, but that’s I think, an interesting fact.

1:35 E: Where are they commonly grown?

B: Well they’re grown out here the western part of Nebraska, but then it’s also in Colorado, Wyoming, and there’s a great deal around the Great Lakes, Michigan and then Minnesota. North Dakota is the largest number of acres. So it is grown in various places. It’s grown up in the northwest and same in Idaho as well.

2:00 E: What is cercospora?

B: Cercospora is a fungus. It’s the generic name for a fungus that causes – it’s an airborne thing. The spores fly through the air. It just causes a foliar disease of sugar beets and other beet related: table beets,
those sorts of things, they’re still susceptible to this.

The other thing that I wanted to point out is that it can be confused with a number of other foliar type diseases that we might see here, but it’s the only one you have to be worried about. It’s the only one that causes economic damage, but it could be confused with alternaria leaf spot or with bacterial leaf spot.

It can be very very devastating, not only to to yield, but also in that it doesn’t sit well in the piles, so it doesn’t process very well. So you just, you just lose a lot of the sucrose because of this infection. Not only in yields, but later on for processing.

2:56 E: What kinds of environmental conditions favor cercospora development in the field?

B: Well it’s – it does have a very specific set of conditions that it needs. It needs a long period of water, duration of at least 11 hours of standing water on the leaves and so forth.

It also needs a [specific] temperature range. If it gets down below 60 degrees Fahrenheit, then then it won’t be a problem. And then if it gets up higher to 95 to 100 then it’s not going to be as much of an issue either. So you need the combination of warm temperatures with  a lot of water.

3:31 E: How do sugar beet growers manage cercospora in the field?

B: Well, there’s a number of ways. One of the first things, like I mentioned a while ago, is you need to make sure that it is cercospora that you’re looking at. ‘Cause if it’s one of those other diseases, you’re going to waste your money because they weren’t going to be economically damaging anyway. And then you’re just out the cost of the chemical.

I guess the most effective way, or the most cost effective way, is through genetic resistance. They have done a really good job of doing – of finding resistance – and then incorporating it into new varieties which are agriculturally successful.

Other things you can do: different types of tillage so it it it can – it basically survives in residues, plant residues. So if you can get that buried or if you can get it out of the way, then that’s going to also help you to a great extent. It’s going to remove that source of inoculum. It doesn’t move a great deal, but it can move through wind patterns.
So, what the idea is to not – if you’ve had a field that had a severe amount of disease, then don’t put another crop the next year within a hundred yards of that.

Fungicides are another option that are routinely used and if you combine those with with the resistance then that that’s even better. But the problem with the fungicides is that there’s populations that have built resistance towards these fungicides and so that’s something you always have to keep in mind. And it’s something that we are continually trying new things to see just to look at different chemistries or different products so that we don’t all – we don’t lose products because of the genetic resistance to that. And that’s so, that’s a huge part of that is not to use the same chemistry multiple times in a year.

5:21 E: How do they track these environmental conditions?

B: Well, we – they do have – we do have a predictive system that has been in place since the 1980’s. It was developed by my predecessor Eric Kerr, and then another UNL faculty member. It’s basically an alert system that that tells you the environment. Its advantage is that it tells you whether the temperature and the moisture has been right for infection to occur. So it doesn’t tell you that the pathogen is present, it just says “hey”.

It’s a monitor, you take it and put it in the fields, and then each day you go and take a look at it. And then it gives you a numerical value of 0 to 14, which is a formula and it’s based on a hourly time for for for the temperatures. Then it spits out a number through a formula of 0 to 14 and so you take that number, that’s the the daily value for disease for that particular day. And the idea is that when you get two successive days in a row where the sum of those two daily infection values reach 7 or higher, then that means the previous 48 hours have been conducive for disease to occur. It doesn’t mean the pathogen is there, doesn’t mean disease is there, it just means that it has been conducive for that to happen. So it makes you have to get out and go check and see if there’s any any of those types of things. So when you do see something and it is building up into the upper part of the canopy, then that’s probably a good idea if if that system told you that it’s time to pull the trigger on it, then you need to you need to have – be prepared to do that.

7:11 E: How has this alert system improved over time?

B: Well I don’t know if we’ve improved it, but we’ve been working with Xin. It was his idea to take this system – he’s not changing the system – but he’s made a a device that allows people to access that information remotely and not having to go out into the field to pick it up. So that’s the key to that thing.

Another thing that we are looking at this year for the first time is essentially a spore catcher and so we put that out there with the the monitor for the for the environmental stuff. And so it should tell us: are the spores present of the pathogen? And so you combine that together with the environment, then that would – I think – be a more effective way of determining whether you need to spray or not.

Because again, spraying indiscriminately is not a good idea. There are chemicals that are available that we can use if things come to that situation.

8:10 E: Does the kind of fungicide a producer use matter?

B: What I’ve found in the past, is that the fungicides that you use are not as critical as using them at all. So if if you don’t do it and you have big problems then that’s worse than than using the wrong product I guess. So that is a critical thing. But you don’t want to wait too late, but you also don’t wait too early too. Because that’s not gonna –
most of these fungicides are contact, so they’re not going to get in the plant and last a long time. So this would be considered a short-term solution, and that that’s why it’s so difficult to work with. Its that you’ve got to be cognizant of the fact that “hey the last 48 hours have been conducive for this so I need to get out there and see if any infections have moved up the plant.” Because if you get them on the newer leaves, that’s when you start to see the issues with the yield drop and all that.

9:13 E: Well folks, there you have it. In talking to Bob about sugar beets and cercospora, we learned what sugar beets are, what cercospora is, and what some of the management techniques are, including using fungicides for short-term management.

See you next time on Farm Sci-Ed, where we go into the science and education behind farming. Be sure to subscribe and follow us for more science and education behind farming. Comment below if you have any questions about cercospora in sugar beets and we’ll be sure to answer it in an upcoming episode. Until then, subscribe to our channel, like this video, and be sure to follow us on our social media. Have a good one!

This transcript has been edited slightly for grammar.

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.