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!