Field Crops Webinar Series - Field Crops Webinar Nematode Management - Quintanilla Tylka
March 21, 2022
- Okay, good evening everybody. I have 7 o'clock on the dot. So I think we're gonna go ahead and get started. Today for our Field Crops Webinar Series, we're gonna be learning about nematode management options for 2022. And we're gonna hear from our very own Marisol Quintanilla, our Nematode Specialist here at MSU, as well as Greg Tylka. He is the Nematode Specialist from Iowa State University. Real quick, I just want to display MSU's, the Diversity and Inclusion Statement. You know that MSU is an Affirmative Action, Equal Opportunity Employer, and all events at MSU are open to all. And quickly, I just want to let everyone know that next week on Monday the 28th will be our final Field Crops Webinar Series. That's gonna be with Dr. Marty Chilvers and Damon Smith. They'll be talking about tar spot management, hybrids fungicide efficacy, and optimizing fungicide timing. With that, I'm going to stop sharing my screen and let our presenters tonight get ready. And just to let you know, you guys can type in any questions that you have in the chat box or in the Q&A. You should see that at the bottom of your screen. And then there will be some time at the end of the presentations where we will go through those questions. Thank you. - Can I share my screen now? - Yeah. - Yes. - Yep. - Okay. All right, so I'll get started. Again, I'm Dr. Marisol Quintanilla, I'm the Nematologist at Michigan State, and I have the great honor of co-presenting with Greg Tylka, he's the Nematologist in Iowa State, and I believe he's the best soybean cyst nematode nematologist in the United States and maybe the world, at least in applied nematology in soybean cyst nematode. So we are honored to have Greg Tylka with us. So I'm gonna present on nematodes in several field crops, such as corn, sugar beet, a little bit of potatoes, other field crops, and then Greg Tylka will focus on soybean cyst nematode. I'll talk a little bit about soybean cyst nematode too towards the end. So, what my lab does. So, I need to put it in presentation mode. So, there's the slide. You can see several nematodes there. So mainly our lab has the objective of assist Michigan agriculture to manage nematode issues on several crops, okay? And we'll first gonna start with net corn. We did a corn survey in the past, and what we found is that one of most nematodes, which is common nematode is spiral nematode, but spiral nematode is not a problem in most crops. It has not been reported to have significant losses. That might be wrong, I have not evaluated that myself, but in the literature, at least, it doesn't show that. Stunt nematode, it's the nematode that the part of the green, stunt nematode is the nematode that was most commonly above ash action threshold, in which we do have literature that it causes damage in corn. So for corn, in Michigan at least, stunt nematode is the nematode that is likely causing the most losses in corn. Root lesion, also is there, found frequently, but most often not above ash action threshold for corn. root knot is a little bit, but it would never be a problem with corn it would be on other rotational crops and surviving on any weeds that would be there. Northern root knot at least. Soybean cyst nematode is commonly found in corn, but not because it feeds in corn, but because many corn growers rotate with soybean. And there's a few others. Some of the most concerning are needle, very infrequently found, not found often, but when it is there, it has devastating consequences. So just a quick show of the map of the areas where we sampled. All the counties that you see darkened is counties that we sampled, okay? So you can see the areas where we... So these are the nematodes we found, again, stunt, root lesion, corn needle, root knot, some cyst nematodes, et cetera. For corn needle nematode, even though we did not find it frequently, when corn needle is there, it can cause huge losses. Yield damage is up to 50%, and the damage threshold is one. So if you find one nematode, it's a nematode per a hundred CCs of soil. That is causing damage already. It's a very, very large nematode. It's generally found in very sandy soil. So your sandy spots will more likely have corn needle nematode. And when it's dry, when the soil dry in the summer, many times in your sample, you're not gonna find it. It kind of migrates just down in the soil. That's a picture of corn needle nematodes. It's actually, for nematode standards, it's a huge nematode. Corn needle nematode as you can see the picture there, really stunts the corn roots. It makes them short and stubby, and it'll make the corn really short. So you'll see the Sandy spots with very, very short corn. It's severe, but again, only in sandy spots and very infrequently. So what to do, mainly this is the case for most corn nematodes, crop rotations, so rotating out of corn, not planting corn back to back if you have some of these nematode problems, cover crops, managing weeds, promoting soil heath, and of course sampling in order to see if you have one of these problems. Corn generally is not a crop that has severe nematode problems. So I would say, do not worry about it, except if you have very sandy spots, and you see corn that is extremely stunted, then you might be thinking of corn needle and you might wanna rotate out of corn for a little bit, okay? Root lesion is extremely common, and I would say most of the time, we did not find it above damage threshold in corn, so I'm gonna skip that. So stunt nematode, most commonly detected above damage threshold, heavier soils. And so again, and stunt nematodes we're finding it more in heavier soils instead of sandy soils. We are finding the corn needle and root lesion in more coarse textured soils, but stunt nematode in more heavier soils, and many times above damage threshold. With most nematodes, rotation is key, you know? Including that one rotating out of corn, not planting corn back to back. Not eternally anyway, plant something else sometimes. With our corn work, and we also done work in wheat, and not every nematode that I mentioned here is the problem in Michigan. I'm just mentioning nematodes that are common in which we have not done a survey of wheat nematodes. That is something that we are planning to do. We did get a grant in order to do this, but some common nematodes throughout the world are seed gall nematode, which is not common anymore. It's actually almost semi-extinct. In the past it used to be a very serious problem, now it is not. So, don't think you have it. You don't have seed gall nematode probably. Cereal cyst nematode, that is a problem in several countries. I do not think it's a problem here, but we have not evaluated. A very common problem here is root lesion nematode. For sure root lesion nematode is widespread throughout Michigan and in the west, in the Western states, in places such as Washington State or California. But the Western states, Pratylenchus neglectus causes huge yield losses in wheat. And we do have Pratylenchus neglectus here. We have found it in fields that rotate with wheat. So, we actually discovered, you know, my PhD student that is working on carrots was sampling in carrots and many carrot growers rotate with wheat. And in the fields that they were rotating with wheat, she found nematodes. She found different species of Pratylenchus, Pratylenchus penetrans, Pratylenchus neglectus and Pratylenchus crenatus. Pratylenchus neglectus is in the literature, very commonly referred as the nematode that causes damage in wheat. So we evaluated. We actually have a grant, we got a USDA NIFA grant to evaluate different root lesion nematodes in corn and wheat rotations. And, to a little bit of results, you can see control wheat with no nematodes, healthier root system that's kind of white clear, but the color is lighter. Pratylenchus neglectus had the most root lost for wheat and Pratylenchus penetrans, still you have darkening of the roots but more root mass than Pratylenchus neglectus. So that's an example of a small trial that we did with wheat. So how do we grow Pratylenchus? We usually grow it in carrot disc, but Pratylenchus penetrans and Pratylenchus neglectus have very different behavior. When you see this here that you see the brown stains throughout the carrot, that is neglectus. It kind of spreads throughout the root, while penetrans, the nematodes kind of are focusing on the center of the root. And so we think that Pratylenchus, that might be the reason why Pratylenchus penetrans affects carrots so negatively. They kind of focused on the apical meristem in the center, and split the root and cause more damage. That's likely because they have different methods of reproduction. Pratylenchus neglectus most commonly has asexual reproduction. So congregating, you know, aggregating, being together does not really give it a big advantage, while Pratylenchus neglectus and Pratylenchus penetrans has sexual reproduction, which it would make sense that aggregation would be a benefit 'cause they get to get married, you know? So this is some work on... So here, see root lesion nematodes, P. Penetrans. We can see how it enters the root. You can see the little worms enter the root. They feed on cells and those cells die, and they cause these lesions, these darkened lesions. That's why it's called the root lesion nematode. Okay, you can actually see nematodes. Those little pink images on the root, those are nematodes inside the root, okay? So here's a small... This is a lab trial in which we tested different products, with different compost and chemicals in order to control Pratylenchus penetrans. PC stands for poultry compost. So you can see water and you can... Just so to summarize, green is 24 hours and blue is 48 hours and I believe yellow is 72 hours. I need to make my... There, yeah, 72 hours. So you can see with water, and this part here is the mortality. So they higher the bar, the more the nematodes died. You can see with water, very low nematode mortality, with poultry compost, we can see high mortality at 48 hours and 72 hours, and that is poultry compost at both concentrations, both 0.1% and 0.5%. And at 0.1% it's comparable to the typical application rates of manure, which is like 2 tons per acre. So you can see layer Ash blend, which is another manure combination, that is poultry compost with a special ash, you know, ash, and also with dairy compost, and you can see also that there's higher mortality at 42 and 72 hours. There's some, you could say more organic products, like Neem oil, also high mortality, and fluazaindolizine, which is a Libro, higher mortality, and some of these products are already registered in potatoes, okay? And you can see that fluazaindolizine also has high effectiveness. And we also tested these products in the field and we had effectiveness on the field. All right. So here you can see also for compost, another trial that we did in the a lab, you can see the light gray with the circles, that's the layer Ash blend that is a combination of manures that are composted from Morgan Composting is the company. Poultry compost in the black with the black squares, and the top one is the dairy manure. You can see clearly, dairy compost does not have a significant impact on nematode numbers. It is not hot enough, you know? While we can see that even at 5% concentration, we have zero nematode survival from the layer Ash blend. And from the Poultry manure, we can see decline with the concentration. The higher the concentration of manure, the higher, the nematode mortality. We tried this again with lower of lower percentages such as 0.1%... 0% means nothing. In other words, we just had plain sand, obviously no mortality. And you can see the different compost. Again, you can see layer Ash blend and the poultry manure. Also, you can see how progressively there was a decline in nematode numbers as we increased the concentration of manure. So other things that we have evaluated for Nematode control is cover crops. In this picture, I showed you just how many times we test these cover crops. We grow them in these little tubes. We inoculate these tubes with nematodes, and then we plant the cover crops in these tubes. And we see if this cover crops increase nematodes or decrease. We grow them for eight weeks, which is enough for the nematodes to go through reproduction and have one life cycle. So Northern root knot nematode is one nematode that we have done. Northern root knot nematode is not a problem in all field crops. Corn has zero problems with Northern root knot nematode because corn is a nonhost for Northern root knot. But Northern root knot can affect many, many crops, many crops, including so soybeans, but it's not really a big problem in soybeans really. It can be a problem in potatoes. It definitely will be a problem in things like tomatoes, celeries and even ornamentals, vegetable crops, you know, carrots, beets, et cetera, could be a serious problem. And you can see Northern root knot how it makes this little, what's the name? You can see these swellings in the roots. That is the typical symptom of this. So here's a trial of different cover crops evaluated for Northern root knot. Here you can see the control crops or the ones that Northern root knot likes to feed on, and you can see carrots. Nematode loves to feed on carrots, celery, tomato. Seems like tomato of all these crops is it's preferred crops, and here is the different cover crops that we tested that we thought might be effective for Northern root knot control. And all of them are better than these three crops obviously, but some of them are totally nonhost. Like any grass, oats, wheat, or oat, wheat and Sudan grass. We had zero reproduction and that is nothing new. We know that Northern root knot nematode cannot feed on any grass. So, same thing with corn, it cannot feed on corn. I would say for most of you guys to grow field crops, Northern root knot would not be a big concern for you, but if you grow some vegetables, it might be, especially if you grow, at least in Michigan, in muck. Muck can have big numbers of root knot nematodes. So you can see here some oil seed radishes, such as control. Actually this is an oil seed radish, and the variety is called control. So it's not like untreated Control. This is actually an oil seed radish that the name of it is called Control. Excellent, very low, almost zero reproduction for root knot nematode, Northern root knot. Same thing with Select, Concorde and Dwarf Essex Rapes, you can see good options. So you can see for root lesion nematode, root lesion nematode is a different story. Very few crops are nonhost for root lesion. Very few. Some of them are poor hosts. You can see carrot, excellent host for root... Here we're talking about Pratylenchus penetrans. So carrot, excellent host, and many cover crops are excellent hosts. Like the, you call the Daikon radish, the Tillage radish, Select, Respect, those ones that said the growers say makes my soil mellow, the one has the big root that is white and thick, all of these are very good hosts for root lesion nematodes. There are a few in the radish group that are very poor hosts. One of them is oil seed radish control. So the same one that was the best for Northern root knot, and there's also Control ASC, and oil seed radish variety Concorde, Dwarf Essex Rape, so these are three options that are effective for root lesion nematode. If you have a problem, root lesion nematode can be a significant problem in potatoes, can be a significant problem in carrots, it can cause even losses in soybeans. I think there's a paper, I think last week or a couple weeks ago, with root lesion nematode effects on soybeans. It's not an important problem like soybeans cyst nematode, but root lesion nematode just affects almost every crop. It feeds on just about everything. So it takes money cut on just about every crop that they grow. All right. So some take home message regarding cover crops, and this goes for all other strategies we mentioned. You should do a soil test and know which nematode you have because in order to decide on most effective cover crop, you need to know what nematode you have. You can submit your sample to the MSU plant diagnostic lab. If you have Northern root knot nematode, in the Brassica, oil seed radish variety Control, oil seed radish variety Concorde, Ecotil, Select, Nitro and Dwarf Essex are good option, and any grass, including corn. Any grass, Sudan grass, oat, wheat. For if you have root lesion nematode problems, the oil seed radish variety control, Concorde, Select and defender are Dood options and Dwarf Essex Rape. Soybean cyst nematode, many growers in Michigan grow sugar beet, I mean sugar beet cyst nematode. There's areas in Michigan that have significant sugar beet production. Sugar beet nematode are those little white things on the roots. You can see with your naked eye. It'll look like little grains of sand attached to the root, almost looks the same as soybean cyst nematode. That's here how the life cycle looks like. Some of the management practices for sugar beet cyst nematode is to plant beet cyst nematode tolerant varieties. There are varieties that can tolerate damage. There are some resistant varieties, commonly not grown in Michigan, but they are grown in other countries. There are trap crops, there's, and I will show you later, there are cover crops that are very effective at reducing sugar beet nematode numbers, and I'll show you a graph later. Crop rotations that applies to almost every crop, changing what you grow. I tried several nematocides for sugar beet cysts nematode. The only one that I found significant effect is Abamectin from a company called Vive. That's the only one I've gotten significant reduction. So here's a greenhouse trial for sugar beet cyst nematode. You can see oil seed radish variety Control, Concord, so same ones that are working the best for root knot, that the best for root lesion, is also working the best for beet cyst nematode. Defender is commonly used for beet cyst nematode, Ecotil, Nitro and Select, these are all better options than sugar beets And if you apply the regular tillage radish, it would be excellent host for sugar beet cyst nematode. So I wanna thank who provides funding for this research, Michigan Soybean Committee, Dairy Doo, that provide all the compost for the trials, the USDA that have provided us grants, Project Green in Michigan state, Michigan Potatoes, Michigan Sugar, The SCN Coalition that has been essential for our soybean work, and North Central IPM that provided us a grant to evaluate cover crops. And here's my team, the team members that have done much of the work that you saw. Syd as my postdoc, Luis as my grad student working on potatoes, Emily was my technician and grad student working on potatoes and root lesion, Amanda is working on ornamentals, she's my PhD student and Elizabeth Darlene, she's working on wheat and carrots, and Syd also works in cover crops and soybeans. So I think we'll leave the questions for very end. Here's picture of some of my teams. And I think that's it. So I'm gonna stop sharing my screen and I'll let Greg Tylka take over. - All right. I assume everything looks okay. - Yep, looks good. - Yes, looks good. - So thanks Marisol for the handoff and near the end of my presentation, I'm gonna hand it back to Marisol for some research results that she has generated. I live in a state where we have 23-24 million acres of only two crops, corn or soybean, and so soybean cyst nematode is kind of the big bully in the state, and it's also rated as the most damaging pathogen of soybean throughout the United States and Canada every year now for 20 or 25 years, and the economic estimates are $1.5 billion, US dollars per year yield suppression from 1996 through 2016. Those were estimates provided by Extension Plant Pathologists in the various soybean producing states. But recently, Penn State University, a faculty member, Paul Esker, had a postdoc who did an economic statistical evaluation, and he came up with a dollar value of 1.5 billion as well, which kind of validated the 20 some years of estimates that were provided by the Extension Plant Pathologists and emetologists. So there's a lot of money being lost in the field due to yield suppression, due to soybean cyst nematode. Part of the reason why it's so damaging is it's so widespread. Every three, four, five years a national map is updated, and in this national map, a single field found to have soybean cyst nematode will be colored in red, and so the map was updated in 2017, and then again in December of 2021, and this shows you the current state of affairs. In that time period between 2017 and 2021, there were 55 new counties found to have SCN in the United States, including Gladwin county in Michigan. Also, there were new discoveries of counties with SCN in Ontario and Quebec and some rural municipalities in Manitoba. And a map like this doesn't get my farmers excited because we're all colored in red, and Illinois is all colored in red, and Indiana is almost all colored in red, but the take home message for my farmers and these farmers, as well as perhaps many folks in your state is if it's spreading to new counties, it's also spreading to new fields within the counties where we found it already. And so it really is an insidious pest that needs to be taken serious and needs to be looked for. I'm gonna jump right to management. Marisol did a great job of describing the biology of sugar beet cyst nematode, which is a kissing cousin to soybean cyst nematode. So she saved me some time there. Jumping right to management, there's really three main things that I recommend to manage cyst nematode, and the first one is growing nonhost crops. Again in my state, it's either corn or soybean, so I'm very thanked that corn is an alternative or an alternating crop with soybean. In other states, there's other options, and your state is probably one of the most diverse in terms of the range of crops that are grown. If you're growing a nonhost crop, what will happen is the juvenile of soybean cyst nematode will hatch out from the egg and it will starve. If that juvenile hatches in a year that a non host crop is being grown, there's no way possible that that's gonna survive till the next season when a potential host will be grown. And so that's good news in my state because we tend to grow corn every other year, and in a first year of corn in Iowa, away from soybeans, first year away from soybeans, we see egg numbers drift up from 5% to 10%, to as much as 45% or 50%. Now with that kind of drop, you would think that if you grew corn for just two or three years, you could virtually eliminate soybean cyst nematode, but mother nature has come up with a pretty formidable pest in that second year, the numbers decrease much less and especially in third year, and the reason is that mother nature has evolved such that many of the eggs are dormant, and they're not gonna hatch in first year away from a host or second year. And when you've grown corn for two years, or maybe three years, the eggs are still there, but all that's left in the soil are eggs that are dormant. And those eggs might not hatch out until five or six or seven more years afterwards. So I advise my farmers that corn is a great management strategy, especially for one year, possibly two, but you simply are not gonna be able to get rid of soybean cyst nematode by growing two or three or four years of corn, or any other nonhost crop. Now, I think about who I'm talking to, and I don't know a lot about Michigan crop agriculture. As I said earlier, I know you grow a bunch of stuff, and so I just want to toss out some considerations, not sure how pertinent or relevant they are, but most edible beans are great hosts for soybean cyst nematode. Things in the Phaseolus enus, black beans, kidney beans, navy beans, and there was a faculty member at North Dakota State University, Berlin Nelson, has published many good papers on the soybean cyst nematode damage to edible beans. And if you hopped on the internet and just searched for edible beans and SCN, you'd probably find some of his papers. Also, peas are kind of an oddball, in that some are really good hosts and others appear to be non hosts depending on the variety. And so in this in particular, you'd have to be careful if you were a pea producer in that knowing what it's the host status of the specific variety or varieties that you would be growing. Now, secondly, wanna talk about nematode protected seed treatments for just a second. They first came on the market in '06 or '07. So we've been kind of 10 or 15 years into to the game. This was a much welcomed addition to the toolbox to manage soybean cyst nematode. And there are lots of options. Now this is way too much information to put on a single slide and expect you to digest it all in a matter of 15 or 30 seconds. I'll just read some of the names for soybeans. They're the seed treatments Avicta, N-Hibit, Votovo, Clariva, ILEVO, Aveo, there's Escalate or Bio ST, it's the same active ingredient, Trunemco and Saltro. I list the different crops, the target nematodes, active ingredients, modes of action. And it'd be really unforgiving for me to show you this expect you to retain all that, but I will email you a PDF file all of this table if you send me a message asking for it. And I think that's maybe the most direct way to get this. If the organizers of the webinar decide to provide it some other way, I'm happy to share it with them. But if you just send me a quick email saying, "Can you send me the table?" I'm happy to do it. I probably won't write you a long flowery message about it, especially if I start to get dozens of requests, but I'm happy to share a PDF file with this table of seed treatments that are available. - They can contact me also, Greg, so they don't have to write to you. You send it to me and I'll send it to everyone. - Okay. Excellent, thank you. So I'm jumping right then to kind of my specialty, and that is resistant soybean varieties. And this is good stuff, in that simply by growing a variety of seed that looks like this or that is resistant, you get this versus this on the left, resistant soybean variety on the right, susceptible soybean variety on the left. And historically there hasn't been a price premium charged for seed of resistant soybean varieties. Technically, scientifically the definition of a resistant soybean variety is one that allows less than 10% reproduction of a susceptible or non-resistant soybean variety. So it's all gauged relative to what reproduction would occur on a susceptible. If you keep it at 10% or below, it's considered to be a resistant variety. And that resistance pays farmers in two ways. The first way is very obvious and people probably can guess very quickly what that way is, and that is more yield. And so here are some summary, average yield data of resistance soybeans versus susceptible soybeans grown in a field experiment in East Central Iowa a few years ago. Our starting egg count was 1300 eggs per 100 CCs of soil. That's about a half a cup of soil. And the resistant soybean varieties on average yielded almost seven bushels per acre more than the susceptibles. But that's the average of about 60 different soybean varieties. So some, if this is the average 52.7, some yielded my much higher than that. And others yielded not quite as much as that, but all in all it provided farmers with almost seven bushels per acre more yield. And that's quite frankly easy money, money in the bank. But there's another payoff, another dividend, that comes in the form of nematode control and farmers get to reap that benefit in the future. So I mentioned, in this experiment, we started out with 1300 eggs per half a cup of soil, at the end of the season, under the resistance soybean varieties that yielded nearly seven bushels per acre more, there was only 2100 eggs per half a cup of soil left behind. And when you consider the variability in egg counts, that is really no increase in egg numbers, 'cause that amount of difference would not be statistically significantly different. But look what was left behind after or underneath the susceptible soybean varieties. So that field or those plots went from 1300 eggs to 8,800 eggs. And in my state, there could be one year of corn grown. And so that might drop to 5,000, but then we're gonna grow another soybean crop and the number would increase with a susceptible. So it's a stair step up in nematode numbers if you're rotating corn with susceptible soybeans, but if you rotate corn with resistance soybeans, you can keep those nematode numbers in check. So as I said, resistance is kind of my thing with SCN. I started in Iowa, at Iowa State in February of 1990. And in 1991, I started putting a list together of the SCN resistant varieties available for farmers. And that list, in 1991, fit on the front side of a single sheet of paper. Our list is updated every fall, and last fall, 2021, there were 872 varieties on the list. So a tremendous increase. I call this a success story in the industry, rising to the occasion and providing lots of choices of resistant soybean varieties for Iowa farmers. Now, to make a resistant soybean. Soybeans aren't naturally resistant. Breeders have to take good agronomic soybeans and then cross them with these breeding lines. Now, these breeding lines, you would never want to grow in a field if you were a farmer because they're not very good agronomically. They fall over or lodge. They don't yield very well. Some of them have black seeds. But they contain these valuable resistance genes. So, soybean breeders have used these seven sources of resistance primarily or published on them as available sources of resistance to cross with good agronomic soybeans to produce offspring that are both good agronomically and control the nematode. Also at the bottom, I note there are many other breeding lines with other sources of resistance that have been released by breeders as well, but there's these seven main ones. So what I've done in this bar graph, it's the exact same bar graph you saw about three minutes ago, that I've colored in the bars based on the source of resistance that it contains. What is the source of the resistance genes? And what you see there is a whole lot of gray, and gray is one source of genetics, it's PI 88788. And all the other possibilities are colored in and red. And we had a nice little trend building up in the mid 2000s with some diversity. But the bottom fell out of that in the mid 2000s. And for Iowa, we're stuck in at about 5% varieties that don't have PI 88788 and 95% of them are a single source of resistance. And if you worked in pest management much, you'd know that this is troubling. It's trouble and it's, I describe it as kind of a train wreck in slow motion. And if that weren't bad enough, that almost everything that's a resistant variety has PI 88788, in Iowa, almost every variety available is resistant. It has the PI 88788 source of resistance. So, even if a farmer did not want to grow a resistant soybean variety, they are the very, very difficult to come by. Virtually 95% of all soybean varieties available in Iowa have PI 88788 resistance, whether you want it or not. Well, because resistance is specific to these sources, these breeding lines, we, very early in my career, started testing the nematodes in the fields we worked in to see how well they were controlled by PI 88788 and Peking and the other sources of resistance. Almost all of our field experiments are on rented ground. We rent from farmers. Our experiments are usually three and a half to five acres. So the farmer rents us the little corner of his or her field and the they farm around us. And I've taken recently a look back at all the test results that we've received. So every field that we conduct an experiment in, we pull a sample and we test it on pure PI 88788 and on pure Peking to see what is that nematodes level of resistance or what is the level of control provided by PI 88788? And in the 1990s, everything was all peachy king. Almost every SCN population we ever encountered in a farmer's field had low reproduction on 88788. In other words, remember 10% is the level below, which there should be re reproduction for 88788 to be considered resistant. So everything was working great. This 10% level of reproduction, another way to think of it is 88788 was providing more than 90% control. But then starting in the early 2000s things changed. So now I'm showing actual data, actual results, and this is percent reproduction of SCN populations in farmers fields that we worked in on pure PI 88788. Each dot represents a different farm field that we worked in, where we pulled the nematode out and grew it in the greenhouse on pure 88788. And even in the year 2000, we had low level reproduction on 88788. I've highlighted that critical level of 10%, which is the definition of resistance. And then as you see, as the years go on, in the fields that we've worked in, the nematodes have developed the ability to reproduce on 88788. I should point out that we only work in a field one time, and we always follow corn. And once we do our one year experiment, we move on. Now we may work with the same farmer in different fields that he or she farms, but these are all different independent nematode populations over the years. It's not like we're going back on the same land, on plots on plots. So this is troubling that there's a nematode out there in a farmer's field that reproduces at 71% on pure PI 88788 where susceptible would be 100. So that means PI 88788 is only 29% effective against this nematode. Now, it's not a surprise because of this bar graph that I showed you earlier, it's called natural selection. It happens with weeds and herbicides, and this is to be expected. It's just troubling to see it verified with data. Now, I'm gonna show you very similar data for just one other breeding line, and that's Peking, because that's really the only other choice in Iowa. It's either 88788 or of that 5% that's not 88788, all of them with one or two exceptions are Peking. So in the 1990s, almost every SCN population we ran into in farmers fields had almost 0% reproduction on Peking. Not anywhere, 3,4,5% is almost 0. And so Peking provided nearly 100% control. But this is what the bar or this is what the graph looks like with reproduction on Peking starting in the year 2000. So the previous graph had blue dots representing the SCN in farmers fields reproducing on PI 88788. Here it's the same fields, the same nematode populations, but the red squares represent the level of reproduction of those nematodes in those farmer fields on pure Peking. And again, I've highlighted the 10% level and we see a much less troubling pattern. Although some of these dots showing for 30, 35% reproduction on pure Peking are a little bit troubling, but we certainly don't see the very troublesome graph that I showed you earlier on pure PI 88788 in contrast to Peking. Now this disparity has real consequences for farmers. And before I move on to just show you some yield data, and right before I conclude, I wanna show you this problem isn't just an Iowa problem. Marisol mentioned the SCN Coalition earlier. One of the thing the Coalition does is gather information from many different states. And in my state, I estimate the 95% of the nematodes out there have greater than 10% reproduction on pure PI 88788. And that's the data I just showed you. For Michigan, Dr. Bird, George Bird, has come up with based on samples that come through the clinic virtually the same number. 94% of the samples that are tested have a high level, greater than 10% reproduction on pure PI 88788. So it is a region-wide problem. And as I said, it's costing farmers money. This is my last data slide and then I have a summary slide. We do lots of these experiments. We measure things from the farmer's fields. This is a variety trial in Southeast Iowa from 2019. And there were 72 varieties in that experiment. Three of them were susceptible, those are the three on the right. 67 have PI 88788 in gray, those are one in the center. And two of them had the Peking source of resistance. On average, all these gray PI 88788 varieties average 51.2 bushels per acre and Peking those two varieties average 72 bushels per acre. Now, I told you we rent from farmer's. We rent three and a half to five acres. The farmer we rented from in this particular field had 25 acres. Around our experiment, I asked him what variety he grew, and it turns out to be one in our experiment, it's that one. And he told me he got 50 bushels per acre, growing 25 acres around us. And so I've done some simple math. And if you take 22.4 bushels per acre times $9 of bushel for soybeans, which is what they were getting back in 2019, that farmer lost virtually $200 an acre in lost revenue due to yield suppression. And then when you multiply that by the 25 acres around the area that we rented from him, it approaches $5,000 an acre in yield loss, and that's at $9 beans. So imagine beans are at $15, 15 and a half a bushel, imagine the yield loss that's occurring now. So this is a very sandy soil, very high stress. Not all Iowa soil is gonna produce these results in the short term, but I tell my farmers, "This is a vision of your future because the nematode is building up reproduction on 88788, and you don't have any choice but to grow it in most of the cases." And if all that weren't bad enough, I'm sorry to be Mr. Gloom and Doom, but we pulled nematode samples at the end of the season from all of these varieties. We started out the experiment with a little less than 5,000 eggs per half a cup of soil under the PI 88788 varieties. We ended up with over 14,000 eggs per half a cup of soil, more actually than under the susceptible soybeans and the Pekings left behind 800 eggs per 100 CCs of soil. And earlier, I reminded you about the long term benefit of keeping nematode numbers in control. So here's my last slide, a summary slide. My advice moving forward, sample your fields to know which ones have SCN, grow nonhost crops, consider using seed treatments and try, and those Peking varieties and start working them in a rotation with resistant soybean varieties that have PI 88788. And at this point, I'm gonna stop sharing my screen and turn it back to Marisol for some final data that relates to rotating resistance sources. - Excellent, excellent. That was fantastic, Greg. I'm gonna share my screen again and.... Wait, and I'm gonna... So, okay, all right. So this is some pictures of soybeans cyst nematode. We also did a trial on soybean cyst nematode. You can see a close up of the soybean cyst nematode, cyst coming out of the root. And this is how it looks on the roots. So I'm not gonna go into all these details because Greg already covered this. I'm just gonna cover the trial. So just to summarize, we did a trial and we published a paper in Crop Protection. So it's a recent paper. It was published by my technician, Cita, and several members of my lab. And the gist of this, we did this for several years, I think for four years in a row. And we had a couple treatments. One was planting Peking back to back, in other words, Peking and the next year Peking on the same spot. Also PI 88788 back to back. Rotate Peking with PI 88788. And also some of them we rotated with susceptible. We did this in a randomized block design, with four or replications. So, here is the results. This is the numbers of nematodes. So you can see in 2018, 2019, 2020. So in 2018, we already had done this for one year. You can see the yellow is when we plant PI 88788, which is 8DV. We summarize 8DV. So PI 88788, deriv variety, 8 deriv variety. And then PDV is Peking deriv variety. So the one that starts with 8, is PI 88788 the one that starts with P is Peking and S is susceptible. So that should be pretty easy to keep track of. So the yellow bars is we rotated PI 88788 with Peking. Definitely you can see clearly that this had the lowest numbers of soybean cyst nematode. This was already the second year 'cause we did this in 2000. We started in 2017. In 2017, our numbers were the same everywhere. In all the treatments, they were pretty much the same 'cause we just started, when we started. So, in 2019, it was a year that flooded a lot. It was a very rainy and moist year. And the soybean cyst nematode had a hard time doing well that year. So I would say that year was not a good year for getting data. And in 2020, we can see again, the yellow bar had the lowest numbers of soybean cyst nematode. You can see that if you plant Peking back to back, it can also reproduce nematodes. So unfortunately there are soybeans cyst nematodes that can reproduce in Peking. And in this field where we did do the trial, they were able to reproduce in Peking much easier after a couple years of planting Peking back to back. So you can see we had good reproduction of Peking. You had good increase of Peking, of the soybean cyst nematode, good increase of soybean cyst nematode. That's the blue bar and the PI 88788 back to back. It's that white and spotted bar, also had a good reproduction of soybean cyst nematode. So, and we can see rotation. So it also reduces SCN density. Okay. And this is yield. We can see we got the highest yield in 2017, when we had the PI 88788 with Peking. Highest yield. The highest yield in 2018, highest yield in 2019. And in 2020, there was some mix there with which one was the highest, but you can see a trend there and there was a negative correlation. So the plots that had the highest SCN numbers had the lowest yield. So there's a negative correlation. In other words, soybean cyst nematode numbers reduces soybean yield. So, so the take home message is mainly soybean system causes yield losses, rotating PI 88788 with Peking gives you the most effective for nematode reduction and yield increase. And that is it. And you can see my paper. It was published in Crop Protection. And you can email if you want to have a copy. You can also look it up in Google Scholar. If you put Quintanilla, my last name, and nematodes, you'll find it in Google Scholar. But anyway, so that's it. And I'm going to stop sharing, and share my... - Great, thank thank you, Marisol, and great. We do have some questions. So let's see, the first one. Well, I think you guys touched on this, are there some cover crops that we should not plant if we have nematode issues because they are a host? And I think you guys did talk about that. I don't know if you wanted to talk about that a little bit more. - Yes. So the answer is, depends which nematode you have and which crop you grow. We found, for oil seed radishes, we found that some of them, such as oil seed radish variety Control, oil seed radish variety Concord, and a few others seem to have effectiveness for every nematode that we tried, okay. I didn't show any graph with soybean cyst nematode, but also this applies for soybean cyst nematode. All of those oil seed radish varieties are nonhost or extremely poor host to soybean cyst nematode. For soybean cyst nematode also, almost every crop is a nonhost except for like dry beans. And there's a few weeds that are also host, but with soybean cyst nematode, pretty much if you're not growing soybeans or dry beans, you're pretty good. But for root lesion and for Northern root knot, there are some cover crops that are excellent hosts for root lesion and excellent hosts for root knot. Same thing for sugar beet cyst nematode. Many brassicas, many radishes are excellent hosts for beet cyst nematode. So yes, there are definitely some cover crops that you want to avoid if you have nematode problems. I would recommend you take the sample, submit it to the plant diagnostic lab. Know which nematode you have. And with that, we can make decisions on nematode varieties. - That sounds good. Thank you for that, Marisol. So we do have a few more questions, but before we go on with that, I just wanted to let everyone know that we're gonna post the survey for credits in the chat box. And that way you guys can follow that link and then fill out the survey. - Hey, Samantha? - Yes. - One of the questions is about, is there any data on seed treatments? And I do have one data slide. Do we have time for me to show that? - Yes, we do. I was just told that I needed to get that out there pretty quick. So, yeah, definitely. So just to let everyone know, you will get a link to the webinar recording emailed to you as well. So I'm gonna go ahead and stop the share here, and then yeah, go for it definitely, Greg. - [Greg] Okay. So, we do these nine main field locations every year across the State of Iowa for a variety evaluations. And starting in 2014, we started putting out paired plots with the seed treatment. So we're not comparing these seed treatments listed on the left against each other. We're comparing the base of insecticide and fungicide that the seed treatments have with the base fungicide insecticide plus the nematode component. So this, for example, is Clariva, plus its base compared to just its base. So we've done over the years, over 180 different paired plot experiments. We do lots of replications, 12 reps with and without the nematode component. And here's the years studied, the products we've looked at, the frequency of a statistically significant yield increase, and then the magnitude of the yield increase. And the last time I presented this, I was asked about what's the frequency of nonsignificant yield increases? And I have to go modify that, although that's kind of against our secret code of being scientists that we only talk about statistically significant. So here's what we have found in our small plot research. And it's not very uplifting in that the frequency of a significant yield increase isn't that great. One out of five, one out of six, one out of seven experiments. So a range from 6% of the time to 22% of the time. When we see a significant increase, it is significant economically. It more than pays for the product, so if you think of the seed treatment as costing between $8 and $25 an acre and the current price of soybeans being 9 to, well, last time I updated my slide, I said 13, but it's over 15 now, the break even point is it's pretty easy to hit that. So back to the question I had the last webinar I gave. Somebody asked, "Well, what's the frequency of nonsignificant, not worrying about statistical significance?" And I don't have those numbers at the top of my head. Rest assured it's much higher, but generally the best any has done is about 60% of the time, the yield with the nematode protected seed treatment is numerically greater than compared to just the base. But it's no better than that in our experiments, no better than 60% of the time. And then what I'm showing here are the frequency or percent of the times where it's statistically significant at a significance level of 10%. These are small plots, four rows wide by 17 feet long, but replicated 12 times with and without the nematode component. I've seen slightly higher frequencies of significant yield increases with strip trials. And so these low percentages will perhaps have a little bit of an explanation because it's small plot work, but typically the more times you replicate the easier it is to pick. In our small plots, we just don't see much higher than the percentages that are shown there in blue. - All right, very good. We do have a couple more questions. What is the most common nematode problem with collard greens? - Okay. Collard greens would be similar to cabbage. So it depends where you're growing it. We did do a vegetable survey. Northern root knot would be a problem if you're growing it like in muck especially, or if you're growing in a soil that has Northern root knot in Michigan. I'm noticing a lot of fields with muck have severe problems with Northern root knot. Root lesion nematode would be a problem. Even beet cyst nematode. If you're growing collard greens in soils that used to have sugar beets, it also can affect collard greens. And so several nematodes can affect collard greens. Definitely not soybean cyst nematode that I know of, but pretty much every nematode that I mentioned. My guess is that most people that grow collard greens in Michigan are not having a significant problem 'cause they're problem rotating with corn or wheat or something like that. But if you are growing vegetables back to back, you can start having a problem. - Okay. Another question, how can big corporations that grow one kind of vegetable continue to grow the same crop without crop rotations? - Why or how? - How? Yeah, so how can big corporations do that without rotating? - Well, I think most growers that I know do some kind of rotation. I have met some vegetable growers that do not rotate at all in muck fields, and their nematode problems are astronomical. They're losing significant yields. I think it is economic, it makes economical sense to rotate, not only for nematodes. I mean, all the fungal pathogens, insect, pests, all kinds of problems build up when you grow the same crop back to back. So I thought it doesn't make sense to grow the same crop over and over again, unless you do it the old fashioned way and you have a highly profitable crop and you are fumigating with an effective fumigant, but if you are just growing the same crop back to back, especially if it's a very susceptible crop to nematodes or diseases, I don't see that as a good alternative. I think you can get away with a while, but eventually it'll catch up with you. But taking soil samples can give you an idea of how things are going. - Okay, great. Thanks Marisol. And I think Greg, you're answering that final question that's up there. - Yeah. - Okay. Great. Then I don't think we have any other questions. Yep, and we're, I think we're good to go. So thank you everybody for attending and don't forget our last webinar, Series Webinar is gonna be next Monday. So, thank you everyone.