Seed Selection for Disease Management

Melissa Bartels Author

12/18/2020 Added

4 Plays

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In this episode, Melissa Bartels and Dr. Tamra Jackson-Ziems talk about how seed selection can help producers managed diseases in their fields. Selecting seeds with a disease package that fits your needs could help your operation next season.

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[00:00:00.000](upbeat guitar music)
[00:00:02.900]Welcome to CropWatch podcast
[00:00:05.350]a production of Nebraska Extension.
[00:00:07.467](upbeat guitar music)
[00:00:12.200]Welcome to the CropWatch podcast.
[00:00:14.660]I am your host, Melissa Bartels,
[00:00:16.860]a cropping systems educator with Nebraska Extension,
[00:00:20.190]serving Butler and Polk counties.
[00:00:22.310]And today we'll be joined by Dr. Tamra Jackson-Ziems.
[00:00:25.920]And we'll be talking about
[00:00:27.210]seed selection for disease management.
[00:00:29.940]How are you doing today?
[00:00:31.440]I'm great and thank you for having me on today.
[00:00:34.500]Great.
[00:00:35.960]And for those that don't know
[00:00:37.160]can you tell us a little bit more
[00:00:38.700]about your role in extension?
[00:00:40.570]So I am an extension plant pathologist
[00:00:43.820]and I have state wide responsibility
[00:00:46.420]to help people recognize, prevent and manage diseases
[00:00:50.470]of corn, grain, sorghum and now soybean too.
[00:00:54.280]Great, so 2020 was an interesting year for diseases
[00:00:58.210]and it was an important problem in some of our corn
[00:01:00.650]and soybean fields in several parts of Nebraska.
[00:01:03.600]Can producers expect
[00:01:04.840]to see these same diseases again in 2021?
[00:01:09.070]Well, we did have some interesting things happen this year
[00:01:12.460]and not of course all good things.
[00:01:14.790]And the unfortunate part is,
[00:01:16.760]is that it's a good lesson in that,
[00:01:19.460]almost all of the diseases that affect our crops
[00:01:23.530]are caused by pathogens that overwinter
[00:01:26.100]in either the infected crop residue or debris
[00:01:30.430]or in the soil.
[00:01:32.090]And so there's a very high likelihood
[00:01:35.440]that if weather conditions are favorable
[00:01:38.030]for that pathogen and disease,
[00:01:39.760]that you're gonna see it again,
[00:01:41.430]if you have susceptible soybean
[00:01:43.370]or corn or whatever crop out there.
[00:01:45.950]And so it probably helps us
[00:01:47.790]to be cognizant of what we've had in the past,
[00:01:50.560]and also familiar with which conditions
[00:01:52.860]do support some of those diseases to develop.
[00:01:56.590]So with those diseases that were present this year
[00:01:59.600]fresh in their mind,
[00:02:00.640]would you recommend
[00:02:01.730]that those producers maybe take some notes for each field
[00:02:05.040]so they know what they had present,
[00:02:07.370]or do you have other recommendations?
[00:02:10.100]I think that's a good idea.
[00:02:11.940]I think especially if you had a serious disease,
[00:02:15.690]something that maybe was more severe than normal
[00:02:19.020]that you should keep track of that.
[00:02:21.250]And maybe also, which hybrids maybe did not perform
[00:02:25.520]in the presence of that disease too.
[00:02:28.190]And that's with the understanding that it may happen again.
[00:02:31.930]That's not always the case with every disease.
[00:02:34.700]And I'll just point out that our rust diseases for instance,
[00:02:38.430]are caused by fungi.
[00:02:40.140]That don't overwinter.
[00:02:41.500]And so we saw a lot of rust this year
[00:02:44.400]and folks in Southeast and South central Nebraska,
[00:02:47.920]would say they see a little bit of rust every year
[00:02:50.970]but that's still blowing up from the South
[00:02:53.300]and not overwintering.
[00:02:55.150]And so it really affects your strategy moving forward
[00:03:00.470]not just for that disease but others.
[00:03:03.360]Yes, I did walk through some fields
[00:03:05.150]with some Southern rust
[00:03:06.420]and came out looking a little orange.
[00:03:08.630]So, it was pretty happy this year in its development.
[00:03:12.010]Is there anything producers might consider
[00:03:14.300]to reduce losses due to diseases next year?
[00:03:17.780]Yes, there is.
[00:03:18.880]And I think we don't always of course think about next year
[00:03:23.830]and pest management during the winter time
[00:03:26.240]but, I really like to emphasize
[00:03:28.120]the importance of hybrid and variety selection
[00:03:31.470]for disease management.
[00:03:33.360]Many people maybe aren't thinking about that.
[00:03:36.690]Our number one priority is always yield.
[00:03:39.180]And another way that we can manage diseases
[00:03:43.810]without the use of pesticides
[00:03:45.850]or reducing the amount of inputs,
[00:03:48.210]might be selection of varieties and hybrids
[00:03:51.310]that have a little more resistance to certain diseases
[00:03:54.020]that you may be seeing as problematic on your farm
[00:03:57.130]or in certain fields.
[00:03:58.860]And one of the things that I think is important to say
[00:04:02.630]is that when I say resistance,
[00:04:04.780]I'm not implying
[00:04:06.060]that we should select immune hybrids or varieties
[00:04:09.600]and expecting one to be immune is unrealistic.
[00:04:14.370]When a plant pathologist talks about resistance,
[00:04:17.280]it's a little bit different
[00:04:18.470]than what some of the other pest management disciplines do.
[00:04:22.110]We're implying that there's less disease
[00:04:24.710]in a hybrid or in a variety,
[00:04:27.630]and not necessarily that there's no disease.
[00:04:30.770]And so there's a huge variety and diversity
[00:04:34.440]and how corn hybrids and soybean varieties
[00:04:36.690]react to diseases.
[00:04:38.720]And if you look closely
[00:04:40.910]at many of our seed company catalogs,
[00:04:44.020]you'll notice that there's a lot of categories
[00:04:46.630]and ratings in some of those.
[00:04:48.740]And they provide feedback
[00:04:51.240]on how they would expect those varieties and hybrids
[00:04:54.040]to react in the presence of some diseases.
[00:04:56.600]And those ratings, although they can be confusing
[00:04:59.670]they can be very important in selecting the right ones
[00:05:03.530]and working with your seed company rep to do that too.
[00:05:06.280]And reminding them what diseases you had
[00:05:09.200]and what your concerns are.
[00:05:11.280]The second part of that too
[00:05:12.830]is that resistance usually to a disease.
[00:05:17.050]We're not talking about genetically engineered traits,
[00:05:19.920]so you're not necessarily gonna have
[00:05:21.680]a high tech fee associated with it.
[00:05:24.150]So it usually shouldn't greatly increase the cost
[00:05:27.680]of that seed selection either.
[00:05:29.880]And it might be a way that you can reduce input cost
[00:05:33.670]for the following year.
[00:05:36.070]Sounds like that would be a great way
[00:05:37.520]if you did have a field
[00:05:38.740]that had a history of a certain disease,
[00:05:41.760]and a lot of that pathogen had built up in the residue.
[00:05:44.960]A great option,
[00:05:46.000]look at some of those different hybrids and varieties
[00:05:48.600]to see possibly what else might be out there
[00:05:51.210]that could work in your operation.
[00:05:54.320]And now would be a great time.
[00:05:55.820]I know a lot of people are probably buying seed
[00:05:57.890]to get that early discount.
[00:06:00.490]Just things like you said that we might not think about
[00:06:03.100]going into winter
[00:06:04.170]but might be a good time to think about those.
[00:06:07.020]When do producers know they should be considering diseases
[00:06:10.240]for resistant hybrids and varieties?
[00:06:14.207]I think that I would consider whether my field or fields
[00:06:18.240]are at high risk for disease development.
[00:06:20.690]And clearly we can't very accurately predict the weather
[00:06:24.810]that far in advance.
[00:06:25.980]So, you won't know if conditions may be wet or very cool
[00:06:31.220]or some other condition that may support disease,
[00:06:34.690]but you are at higher risk if you've had severe disease
[00:06:38.290]in the past, with any of those that can overwinter.
[00:06:41.230]Just like you said, we have a greater load,
[00:06:43.890]inoculum load going into winter.
[00:06:46.110]So you'll have more that we would expect to survive
[00:06:48.970]into the next season,
[00:06:50.450]ready to cause disease again when you rotate back.
[00:06:54.150]And so that would be something that I would consider,
[00:06:57.270]again, if you're trying to look at ways
[00:06:59.720]you can reduce input cost,
[00:07:01.130]that might be one way you can do that.
[00:07:03.990]And I would also keep in mind too,
[00:07:06.560]that unfortunately, some of the common production practices
[00:07:09.790]that we're using now,
[00:07:11.920]we use some of those for other reasons,
[00:07:14.010]for soil health and other management reasons.
[00:07:17.110]But some of them do increase the risk for certain diseases,
[00:07:20.720]ones like when we plant continuous corn
[00:07:23.130]or continuous soybean,
[00:07:24.840]or when we're using a minimum or no tillage.
[00:07:27.730]And we have great reasons for doing all of those
[00:07:30.010]but they can all increase our risk of several diseases.
[00:07:33.600]And that might mean it's even more important
[00:07:35.660]to select disease resistant varieties
[00:07:37.950]and, that you may have to rely more often
[00:07:40.700]on the use of foliar fungicides
[00:07:42.660]if you're using any of those practices.
[00:07:46.300]It's all a balancing act, isn't it?
[00:07:47.900]To try to reduce. It sure is.
[00:07:49.563]Huge risk but also get all the benefits
[00:07:51.917]of all the other aspects in the field.
[00:07:54.580]These are hard decisions.
[00:07:56.370]Yes.
[00:07:58.430]Are there specific diseases
[00:07:59.850]for which producers should consider selecting
[00:08:02.180]resistant hybrids and varieties?
[00:08:05.740]Absolutely.
[00:08:06.960]And, I always have a list of things in my head
[00:08:11.490]to be on the lookout for,
[00:08:13.020]and ready to react to during the season
[00:08:16.230]and warn people about.
[00:08:18.010]And some of the common ones that we've seen in corn
[00:08:21.780]for the last handful of years, for instance.
[00:08:25.110]I think about this past year,
[00:08:27.680]we actually saw more Northern corn leaf blight in some areas
[00:08:31.530]and that's a fungal disease.
[00:08:33.650]And although it wasn't severe in most areas
[00:08:36.610]it was in a few areas
[00:08:38.160]and a few people did need to use fungicides on that disease.
[00:08:42.690]And also gray leaf spot's very common.
[00:08:45.640]We didn't see as much gray leaf spot this year
[00:08:48.170]because probably of cooler night temperatures
[00:08:50.870]but in contrast,
[00:08:52.090]that supported the Northern corn leaf blight.
[00:08:53.890]So we saw an increase of that.
[00:08:56.320]But we have resistance to both of those diseases.
[00:08:59.510]And so you might think back to what you've seen,
[00:09:02.050]not just this past year, but historically
[00:09:05.120]and watch those ratings on the hybrids
[00:09:08.470]that you are selecting.
[00:09:09.680]On the other side, though, I would also strongly recommend
[00:09:13.640]people to select resistant varieties
[00:09:15.870]especially for bacterial diseases.
[00:09:18.850]Bacterial leaf streak was very severe
[00:09:21.570]in some fields this year.
[00:09:23.760]It's a newer disease to many people and it may be alarming.
[00:09:28.590]And for instance, this year,
[00:09:30.140]I saw bacterial leaf streak by mid season
[00:09:32.590]was all the way to the top of the plant in many fields.
[00:09:36.280]It looked pretty bad out there.
[00:09:38.770]But we know that this is a deal difficult disease
[00:09:41.700]for our companies to work with,
[00:09:43.410]and we're working with them on that too.
[00:09:46.140]Difficult for them to collect the data
[00:09:48.640]they need to share with you and rating,
[00:09:51.220]so you don't have ratings, very commonly for some of them.
[00:09:55.150]But what's out there is helpful,
[00:09:56.620]but even just that conversation with your seed company rep.
[00:10:00.610]The other example most people are more familiar with
[00:10:03.310]is Goss's wilt or more appropriately
[00:10:06.130]Goss's bacterial wilt and blight.
[00:10:09.030]This one has a historic precedence in Nebraska.
[00:10:13.890]And although we don't normally see it
[00:10:16.610]until after some wounding event like hail or high winds.
[00:10:21.300]This is one that sneaks up on people
[00:10:23.400]'cause if they haven't seen it in a handful of years
[00:10:25.440]maybe they don't actively select a resistant corn hybrid.
[00:10:29.100]And then they have a surprised,
[00:10:30.630]a light hail event and suddenly it's everywhere.
[00:10:33.690]And so if you've had it in the past,
[00:10:35.620]I would continues to select a resistant hybrid for that
[00:10:38.610]because they do work really well
[00:10:40.730]and we do have good ratings for Goss's wilt.
[00:10:43.340]Finally on corn,
[00:10:44.600]Southern rust is one that I'd bring up
[00:10:47.780]and maybe not for reasons you might think.
[00:10:50.120]I mentioned earlier the pathogen causing Southern rust
[00:10:53.300]is a fungus.
[00:10:54.560]It does not overwinter in Nebraska though.
[00:10:57.360]We literally watch it blow up here on Southern winds
[00:11:01.030]from some of those Southern States.
[00:11:03.750]And although it doesn't overwinter,
[00:11:06.370]in irrigation areas especially in Southeast
[00:11:09.260]and South central Nebraska,
[00:11:10.630]we continue to see this almost every year
[00:11:14.407]and some years it's quite severe.
[00:11:16.570]And when I started some 15 years ago,
[00:11:20.280]we didn't have resistance for Southern rust,
[00:11:23.550]but now we do.
[00:11:24.760]Some of our companies are working more
[00:11:27.810]to incorporate resistance or select for variety
[00:11:30.660]or hybrids that have some resistance.
[00:11:33.100]And that could be valuable to folks growing in those areas
[00:11:36.390]where they see it repeatedly.
[00:11:38.120]And so I think that definitely be worth your time.
[00:11:41.160]When we switch and think about soybean,
[00:11:43.080]we've got some very good examples
[00:11:45.260]of how resistance can save you money
[00:11:48.370]as far as disease management.
[00:11:49.920]And one of the best ones is for sudden death syndrome.
[00:11:53.560]And so we've got really good data from regional projects
[00:11:57.930]from across the Midwest,
[00:11:59.910]that soybean varieties that are resistant to SDS
[00:12:03.300]can reduce disease severity by as much as 80%.
[00:12:07.540]And that's a huge savings for you.
[00:12:09.820]And we also now have some seed treatment fungicides
[00:12:13.990]that we know do a good job
[00:12:16.060]managing sudden death syndrome,
[00:12:18.130]like ILeVO and Saltro are the two that come to mind
[00:12:21.610]that we have now.
[00:12:22.610]And so, the variety selection is number one,
[00:12:26.080]that's given us the best control.
[00:12:27.440]But if you've had severe disease in the past
[00:12:30.390]widespread over one or more fields,
[00:12:32.790]it may also pay for you to add that seed,
[00:12:35.200]one of those seed treatments
[00:12:36.480]on top of your resistant variety.
[00:12:39.470]Next one I would consider selecting resistant variety for,
[00:12:43.320]might be frogeye leaf spot.
[00:12:45.840]And frogeye leaf spot
[00:12:48.040]maybe wasn't severe for some people in 2020,
[00:12:51.810]but it was in some places further North in the state
[00:12:55.010]and is even the year before.
[00:12:57.240]And you've been hearing more and more talk about frogeye
[00:13:00.600]because now, at the University of Nebraska
[00:13:02.900]we've confirmed fungicide resistance in that pathogen,
[00:13:07.090]to the group 11 QoI fungicides
[00:13:09.910]are what we used to call strobilurins,
[00:13:12.330]a very important group of fungicides.
[00:13:14.430]But now they don't work well on that disease.
[00:13:17.560]And we're just learning how widespread that might be
[00:13:20.460]doing a survey right now.
[00:13:22.660]But, one way that you can help mitigate
[00:13:26.050]that is, just trying to get a hold of a resistant variety
[00:13:29.750]to put out there.
[00:13:30.720]And some of those may be more difficult to find
[00:13:32.920]but, be prepared that if you have a lot of frogeye
[00:13:35.760]and you need a fungicide,
[00:13:37.330]you might need to consider a different fungicide
[00:13:39.840]mode of action to get effective management.
[00:13:43.370]And finally, soybean cyst nematode.
[00:13:47.110]This is still the number one soybean pathogen
[00:13:50.550]in the country.
[00:13:51.383]And so we do have resistance to the nematode.
[00:13:54.520]Most of that, unfortunately,
[00:13:55.730]comes from one source of resistance, PI 88788.
[00:14:00.460]And we are getting adaptation of the nematode to that.
[00:14:04.630]The good news is we do have a new source of resistance
[00:14:08.110]that has been released and incorporated
[00:14:10.260]into commercially available soybean varieties.
[00:14:14.130]Right now, those are available through Golden harvest.
[00:14:17.480]That PI line is PI 89772.
[00:14:21.880]So there's not many of them right now
[00:14:23.800]but that variety or a different one,
[00:14:26.640]say with the peaking background or another
[00:14:29.520]would be a good option to rotate with.
[00:14:32.240]And help keep soybean cyst nematode
[00:14:34.250]population densities low.
[00:14:35.870]Where that's when they're easiest to manage
[00:14:37.890]is if when you can keep them low,
[00:14:39.740]not allowing them to spike,
[00:14:41.420]it's because they're hard to drive down.
[00:14:43.860]In addition, you've also got a lot of options
[00:14:46.540]for Phytophthora root and stem rot management.
[00:14:49.600]And so this is a disease that has been a particular problem
[00:14:53.470]for a number of people across Eastern Nebraska.
[00:14:56.900]And the selection of varieties for Phytophthora resistance
[00:15:01.640]might be confusing.
[00:15:03.330]For Phytophthora, we have race specific genes
[00:15:06.980]like Rps 1c and Rps 1k.
[00:15:10.980]And those are examples of genes that give you very good,
[00:15:15.330]excellent control of specific races of Phytophthora,
[00:15:18.870]which you may or may not have an idea
[00:15:21.360]of what you have in those fields.
[00:15:23.380]But those are the ones that have been the most effective.
[00:15:26.210]Well, on top of that
[00:15:27.270]we also have tolerance ratings for many of our varieties.
[00:15:31.560]And so what that means is
[00:15:33.610]tolerance is specifically in this case,
[00:15:36.450]means a reduction of disease severity across all races.
[00:15:41.900]Not as effective as what you get for Rps 1c or 1k
[00:15:45.870]but if there were other races
[00:15:47.360]that weren't controlled by those resistance genes,
[00:15:50.200]tolerance means that you'd still get some level of reduction
[00:15:53.970]by selecting
[00:15:54.803]one with the highest possible level of tolerance,
[00:15:57.500]in addition to that Rps gene.
[00:16:00.260]And so we definitely recommend that for fields
[00:16:02.730]where you've had a chronic problem with Phytophthora.
[00:16:05.800]If Phytophthora was a problem, though,
[00:16:07.600]I would encourage you to also consider
[00:16:10.440]a seed treatment fungicide,
[00:16:12.470]but just know that Phytophthora is a fungal like organism.
[00:16:17.310]It's actually an oomycetes
[00:16:18.910]and the same seed treatment fungicides that work on it,
[00:16:22.850]don't necessarily work on other things and vice versa.
[00:16:27.000]And so if you know what you've got is Phytophthora
[00:16:29.800]and you're looking for seed treatment options,
[00:16:31.840]we've got several to choose from,
[00:16:34.020]things like Ethaboxam and Exophiala propylene.
[00:16:37.640]And also some of the older materials
[00:16:39.440]that we know did a good job
[00:16:40.810]like Metalaxyl and Mefenoxam.
[00:16:43.550]But if you use either one of those two,
[00:16:46.240]just know that you have to use the higher rate
[00:16:49.000]to get good effects on Phytophthora control.
[00:16:52.440]That would be my talk for each corn and soybean
[00:16:55.110]and I hope people will reach out
[00:16:57.320]if they have any questions about that,
[00:16:59.130]and let us know what they're thinking.
[00:17:01.738]Great, thank you so much.
[00:17:03.330]Yes, just like with weeds and other pests,
[00:17:06.730]it's always really important,
[00:17:08.560]make sure that we're trying to rotate out
[00:17:10.240]and not just depending on one variety or hybrid
[00:17:13.850]or mode of action or any of that,
[00:17:16.460]'cause unfortunately that just causes our pest, our weed
[00:17:20.500]to mutate a little faster and overcome that.
[00:17:25.500]It's worth mentioning too, that I didn't mention earlier
[00:17:29.490]that I don't think we're talking enough
[00:17:31.830]about the impact of soybean cyst nematode
[00:17:34.830]on SDS development.
[00:17:37.040]And so we're talking about a nematode and a fungus
[00:17:40.030]working together, well not literally,
[00:17:42.610]but from the plants perspective, it's a double whammy.
[00:17:46.200]And so then when the nematode is present in a field,
[00:17:50.980]you are more likely to have SDS develop earlier
[00:17:54.670]and become more severe than if the nematode wasn't there.
[00:17:58.150]And so that's just one more reason
[00:17:59.870]to manage the nematode too.
[00:18:02.540]Great, great advice.
[00:18:04.520]Do you have any programs or articles coming out
[00:18:07.900]that are related to this topic?
[00:18:09.960]Well, we've been trying to get this information out
[00:18:13.320]in a number of ways.
[00:18:14.860]And so we do have a CropWatch article that was released,
[00:18:18.080]you and I co-authored that.
[00:18:19.590]I think November the 19th is when that came out.
[00:18:23.020]And we also,
[00:18:25.070]I think people will see the Market Journal episode
[00:18:27.860]coming up this week,
[00:18:29.190]here in a couple of days December 11th or so,
[00:18:33.330]we'll be talking about it there.
[00:18:34.600]No, probably hear and see this
[00:18:36.560]on a few other and social media
[00:18:38.372]and I'm guessing maybe even on the radio.
[00:18:42.090]We just can't stop thinking about some of these things
[00:18:45.690]and in the wintertime,
[00:18:46.940]and planning ahead can certainly save you some money.
[00:18:49.760]Definitely, and then like you said,
[00:18:51.460]now is the time to make those decisions.
[00:18:53.770]And when it's fresh in your head
[00:18:55.210]of what fields had what problems or if any,
[00:18:58.300]and how to try to mitigate those risks moving forwards
[00:19:01.660]in the next year.
[00:19:02.800]Well, thank you so much for joining me today.
[00:19:04.980]And I hope everybody has a safe holiday season
[00:19:08.830]and we'll catch you next time.
[00:19:10.740]Thank you.
[00:19:11.573](upbeat guitar music)

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Seed Selection for Disease Management

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