2 - 2020 Soybean Management Field Days - Soybean Gall Midge: Research Updates on a New Pest of Soybean

Nebraska Soybean Board & Nebraska Extension Author

09/25/2020 Added

244 Plays

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Soybean Gall Midge: Research Updates on a New Pest of Soybean - Justin McMechan, University of Nebraska Crop Protection and Cropping Systems Specialist. This presentation includes: Overview of symptomology and scouting for soybean gall midge; Current distribution and field pressure from survey conducted in Nebraska; and Updates on biology, ecology and management challenges

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[00:00:02.424](upbeat music)
[00:00:07.280]I'm Justin McMechan and I'm a crop protection
[00:00:08.920]and cropping systems specialist.
[00:00:09.923]Today I'm gonna discuss strategies
[00:00:11.720]for soybean gall midge management,
[00:00:13.250]a new species that's been found in the state recently
[00:00:15.487]and insect management in cover crops.
[00:00:18.460]We'll start by talking about strategies
[00:00:20.380]for soybean gall midge.
[00:00:21.600]As I mentioned, this is a new pest
[00:00:22.618]that recently showed up in the state
[00:00:24.173]and we've been doing a lot of things to try and understand
[00:00:26.540]its distribution, its biology and ecology.
[00:00:29.560]Then this year applying a lot of different strategies
[00:00:31.660]to this insect.
[00:00:32.493]A number of you that are listening to this
[00:00:34.240]are probably impacted by soybean gall midge
[00:00:36.540]or know neighbors that are.
[00:00:37.963]So the goal of this video is to kind of
[00:00:40.240]provide you with some background on soybean gall midge.
[00:00:42.430]Maybe you know some of that already,
[00:00:44.290]show you its distribution in the State
[00:00:45.840]based on a survey we're conducting this year
[00:00:48.000]and then lead into some of those strategies that...
[00:00:49.995]This is the beginning of this conversation,
[00:00:52.010]later this fall we'll have a lot more to say about those.
[00:00:54.903]My colleagues couldn't join me today,
[00:00:57.682]but Tom Hunt, who's up in the Northeast
[00:00:58.717]has done quite a bit of research on soybean gall midge
[00:01:01.440]in cover crops.
[00:01:02.640]Bob Wright, who's down in Lincoln and works at a scale
[00:01:05.460]and Elliot Knoell, who's a research project coordinator
[00:01:07.675]that does a lot of the cover crop work
[00:01:09.590]and helps on soybean gall midge.
[00:01:11.520]Soybean gall midge is a new pest as we mentioned.
[00:01:13.185]Looking at this slide you'd say well, Jesus!
[00:01:14.977]It's been around since 2011.
[00:01:17.480]It has, but we never considered it
[00:01:18.854]an economic threat at that point,
[00:01:20.758]I was at a pretty low level of concern.
[00:01:22.358]We usually found it around now in the season.
[00:01:26.330]Typically it wasn't causing any plant death,
[00:01:28.320]it was just present on plants that were
[00:01:30.250]historically had received some sort of injury
[00:01:32.410]earlier in the season.
[00:01:34.140]2015 and 16, it was documented in other states,
[00:01:36.800]South Dakota and Iowa.
[00:01:38.360]But no part of those states did anybody raise concerns,
[00:01:41.770]at least at that point in time
[00:01:43.170]on its likelihood of causing any injury.
[00:01:45.260]Then in 2018, in about June,
[00:01:48.000]I got a call from Aaron Nygren
[00:01:49.870]indicating some problems in Saunders County area
[00:01:52.040]just south of the station a couple miles.
[00:01:55.854]A tour to that county showed that
[00:01:57.420]it was already present in fields,
[00:01:59.230]except we were in late June early July.
[00:02:01.160]So two months earlier than anticipated.
[00:02:04.160]With that, came a number of calls from other states
[00:02:05.920]that were also experiencing issues.
[00:02:08.570]We're able to collect adults using some emergence cages,
[00:02:10.900]which is the cornerstone of how we manage soybean gall midge
[00:02:13.430]and monitor it in these various states.
[00:02:16.303]That led to the identification of a new species in 2018.
[00:02:18.649]That should be underlined and highlighted
[00:02:20.970]not for its notability to entomologists,
[00:02:24.560]but for the fact that we're way behind
[00:02:26.210]with an insect like this
[00:02:27.160]and trying to find management strategies.
[00:02:29.340]We appreciate the growers that are working with this
[00:02:31.150]and dealing with this, their patience
[00:02:33.340]as we learn more about this insect.
[00:02:35.441]Here's an array of plant symptoms.
[00:02:38.200]If you have soybean gall midge,
[00:02:39.410]you've probably already seen a lot of this.
[00:02:42.101]It suggests by the name gall,
[00:02:44.550]that it should form these large galls on the stem.
[00:02:46.640]But in fact, this the stems kind of cave in a little bit
[00:02:49.710]turned black
[00:02:51.380]and underneath that blackened area, if you peel that open,
[00:02:53.630]if it is soybean gall midge,
[00:02:54.920]you'll find orange or white larvae
[00:02:56.335]depending on the time of infestation
[00:02:58.400]and when adults arrived in that field.
[00:03:00.510]So initially, we find these white larvae
[00:03:01.940]for the first seven to nine days.
[00:03:04.230]Later, they start to transition to this orange color
[00:03:07.340]and that slowly decays the outside of that plant
[00:03:10.550]towards the inner part which eventually results
[00:03:12.077]in the plants wilting and dying
[00:03:13.491]because they can't move water or nutrients
[00:03:15.830]through their stem.
[00:03:16.950]This is an edge infesting pest
[00:03:18.700]so typically, we find it the first few rows.
[00:03:20.206]So I've been out scouting fields.
[00:03:21.961]I never have to step more than a row or two into a field
[00:03:25.240]if I'm likely to find soybean gall midge in those fields
[00:03:28.350]and it hasn't been causing a significant injury yet.
[00:03:31.570]This is a current map of the five states
[00:03:34.680]where we found soybean gall midge so far,
[00:03:37.060]so we added Missouri late last year,
[00:03:39.680]but it's present in Nebraska, Iowa,
[00:03:41.810]South Dakota and Minnesota.
[00:03:42.643]You can see it's covered most of our eastern Nebraska area.
[00:03:46.960]There are different colors on that map
[00:03:48.350]to indicate 2018 when it was first discovered,
[00:03:51.360]as well as 2019, where we added six counties in Nebraska.
[00:03:54.189]This year, we've already added not one but second county,
[00:03:57.620]Polk County just as I arrived at this site.
[00:04:00.150]It's only 50 feet into Polk County.
[00:04:01.900]I'll continue to sample the county today.
[00:04:04.150]So it's good to keep up to date with a new insect like this,
[00:04:07.037]cos it initiate strategies for the next year being alert,
[00:04:10.260]whether you're a consultant or a producer.
[00:04:11.669]So right now we're at five states and 100 counties infested
[00:04:15.470]and obviously the severity in these counties
[00:04:17.700]varies quite a bit.
[00:04:18.540]We have significant injury in some fields,
[00:04:21.870]and even within the same county drive 10 miles
[00:04:24.070]and some growers don't even know
[00:04:25.550]soybean gall midge is around or a threat.
[00:04:28.330]This project as well as a couple other projects
[00:04:30.590]I'll discuss today,
[00:04:32.610]was funded by the NCSRP
[00:04:33.730]or North Central Soybean Research Program
[00:04:36.340]as well as the United Soybean Board.
[00:04:37.903]So without their support,
[00:04:39.330]as well as the Nebraska Soybean Board,
[00:04:40.498]I'd have a pretty blank presentation to show you today.
[00:04:43.580]So we greatly appreciate their support.
[00:04:47.530]This is a more detailed look into Nebraska
[00:04:49.530]and specific sites where we've sampled.
[00:04:52.050]The dots you see on there represent
[00:04:53.690]varying degrees of pressure.
[00:04:55.320]We started this survey on July 19th.
[00:04:57.260]We're still going today.
[00:04:58.703]We've been adjusting to different fields,
[00:05:00.710]both corn and soybean.
[00:05:02.600]Historically when I talk about soybean gall midge
[00:05:05.180]next to soybean is a low pressure field
[00:05:07.040]because that is likely corn of the previous year.
[00:05:09.660]The likelihood of finding soybean gall midge
[00:05:11.780]in those fields is pretty low.
[00:05:13.770]But you can see on the map here,
[00:05:15.470]we could not find an uninfested field
[00:05:17.210]and Lancaster, Cass, Sarpy or Saunders County,
[00:05:20.550]We even targeted low pressure areas,
[00:05:22.189]soybeans across from soybeans,
[00:05:24.890]these fields didn't show any signs of wilting,
[00:05:27.110]but we still have presence of soybean gall midge.
[00:05:29.150]This is something for especially growers in those counties
[00:05:32.600]to pay attention to next year
[00:05:33.860]because it's frequent across the landscape in those areas
[00:05:37.180]and pose a significant threat.
[00:05:38.647]We've been along the York and Polk County line
[00:05:40.824]as well as out in Merrick.
[00:05:42.710]We can find it on sweet clover in York County,
[00:05:45.137]but we cannot find it on soybeans.
[00:05:47.450]This is an interesting thing with soybean gall midge.
[00:05:50.150]It has a few other hosts that we've identified it on,
[00:05:52.910]but this is something growers need to pay attention to.
[00:05:55.168]Larval numbers on these plants range anywhere from
[00:05:57.650]one larvae on a plant up to 118 on soybeans
[00:06:01.090]and on sweet clover you found as many as 225.
[00:06:04.780]So lots of work to be done in this area
[00:06:06.780]and the photo you see here
[00:06:07.760]is actually from Colfax County area.
[00:06:10.213]That just shows you we're seeing what we saw in 2018
[00:06:13.290]in a number of fields,
[00:06:14.390]those fields are the red dots you see on that map.
[00:06:18.980]So scouting, where to scout you can probably indicate by now
[00:06:20.660]where we need to scout these corn soybean interfaces
[00:06:23.640]with the highest risk areas
[00:06:24.810]coz it's likely last year soybean field.
[00:06:27.330]If you're gonna find it go into an area
[00:06:28.770]with dense vegetation,
[00:06:29.720]you got a few trees along the edge a bush,
[00:06:32.059]walking next to those areas directly.
[00:06:33.564]That's the highest likelihood of finding it in the field
[00:06:36.527]and the first one to two rows is the best place.
[00:06:39.460]We have a website soybeangallmidge.org
[00:06:43.630]and has a video in there
[00:06:44.940]on how to scout for soybean gall midge.
[00:06:46.144]So if you're still wondering after this
[00:06:47.970]and wants kind of specific details,
[00:06:49.580]that's a good place to go.
[00:06:51.650]Then later around now,
[00:06:53.410]wilting becomes pretty apparent in these fields.
[00:06:55.190]It can be confused with other things like phytophthora.
[00:06:57.861]It's important to get out into those fields,
[00:06:59.760]look at those plants and make sure...
[00:07:01.670]In fact, right on this site, we have phytophthora,
[00:07:03.736]which I walked over thinking was gall midge,
[00:07:05.610]picked it up and it's clearly phytophthora
[00:07:07.476]and then 20 feet away from that I found a plant
[00:07:09.570]that doesn't have really much symptomology
[00:07:12.070]but has soybean gall midge at the base of that plant.
[00:07:14.431]So that's why we added Polk County today.
[00:07:16.745]So here's a little more on scouting.
[00:07:18.381]When you get into these fields,
[00:07:19.870]you wanna lean right down to the base of the plants
[00:07:21.530]below even the cotyledonary node next to the soil line
[00:07:24.250]look for a blackened area,
[00:07:25.810]you can bend or break those areas over
[00:07:27.990]and underneath that blackened areas where you might find
[00:07:30.270]soybean gall midge if it's present.
[00:07:32.995]There are two other hosts identified for soybean gall midge,
[00:07:35.495]as I mentioned earlier sweet clover,
[00:07:37.287]we have a yellow and white sweet clover.
[00:07:39.420]White tends to be alive longer, throughout the summer
[00:07:41.857]and so that's a good one to target
[00:07:43.262]if you're wondering if it's on those hosts.
[00:07:45.140]Then alfalfa, it's particularly hard to find
[00:07:46.842]we can't find it on alfalfa.
[00:07:49.009]But typically the numbers are quite low,
[00:07:50.820]and it's actually inside the stem,
[00:07:52.440]so you have to crack those stems open.
[00:07:54.940]We waited a long time in 2019 to add these hosts.
[00:07:58.570]We did larval morphology, DNA sequencing and adult rearing
[00:08:01.690]to determine that they were hosts.
[00:08:04.950]The ecological role of them isn't clear,
[00:08:06.590]we don't see significant pressure from these hosts,
[00:08:08.560]they're likely background hosts relative to soybean.
[00:08:12.320]Soybean adult monitoring network,
[00:08:13.784]the network can consist of 36 sites across four states.
[00:08:17.806]Here in East-Central Nebraska,
[00:08:19.340]we monitored this daily during the spring.
[00:08:21.480]It's easy to join this.
[00:08:23.300]You just have to send me an email
[00:08:24.730]put in the subject line soybean gall midge alert network.
[00:08:27.720]This puts you on an alert system
[00:08:28.906]that whenever we get new emergence
[00:08:30.870]or things are happening in an area we can add you to that.
[00:08:32.940]We try not to inundate our clientele with this.
[00:08:35.223]So we do a lot early season and then ease off
[00:08:37.507]once management practices are out of the way,
[00:08:41.240]or at least not practical anymore.
[00:08:42.758]There's the website again to go
[00:08:44.467]where you can find maps like the map you see on your screen.
[00:08:49.190]First emergence for this year was June 10th in Cass County,
[00:08:52.770]quickly escalated throughout the state
[00:08:54.990]with emergence occurring at all the sites in Nebraska
[00:08:57.180]within nine days.
[00:08:58.700]Each site, we typically have around 12 cages
[00:09:00.820]as little as six, but each time we get a single adult,
[00:09:03.620]that's about 1000 adults per acre emerging,
[00:09:06.300]which is highly variable because the cages are quite small
[00:09:09.950]relative to the total land area that's being estimated.
[00:09:13.290]But here on the map, you can see the numbers,
[00:09:15.360]the dates of when it emerged.
[00:09:17.242]It pushed all the way up into South Dakota
[00:09:19.730]within that nine day mark two in Minnesota.
[00:09:22.990]Lots of people asked for the life cycle
[00:09:24.320]of soybean gall midge, I appreciate this.
[00:09:26.880]We found eggs this year.
[00:09:27.721]So we now know what those look like,
[00:09:29.022]they look like little cigars.
[00:09:30.802]White cigars are typically in pairs
[00:09:32.720]that are in sets of three.
[00:09:34.660]Those hatch,
[00:09:35.493]they go through to larval instars that are white
[00:09:37.714]and then as they transition to the third instar
[00:09:39.719]they turn orange.
[00:09:41.280]That orange is because they can synthesize
[00:09:42.549]what's called carotenoids, which is unusual in insects.
[00:09:45.560]There's only two others aphids and mites
[00:09:47.335]that are known to do that,
[00:09:48.168]but that's why they have that orange color that we see
[00:09:50.050]which is nice for identifying them in the field.
[00:09:53.060]The pupae then after they've gone through the third instar
[00:09:55.630]they fall off these plants, they pupate in the soil.
[00:09:58.399]We've done some soil work,
[00:09:59.353]they'll go as far down as five inches,
[00:10:01.950]but typically they're in the top inch and a half
[00:10:04.420]and then adults will emerge
[00:10:05.309]and that cycle will repeat itself.
[00:10:07.600]Last year, we went through two full cycles and soybeans,
[00:10:11.010]this year was really hard to tell
[00:10:12.450]because we had emergence overlaps of over 10 days,
[00:10:14.850]so it was impossible to tell generations apart.
[00:10:17.190]This year, we don't have any good information on that.
[00:10:19.483]You could see life cycle anywhere between 28 and 32 days,
[00:10:23.280]It may have been faster this year
[00:10:24.840]just based on first adult captures.
[00:10:27.080]But again, very difficult to tell the difference.
[00:10:29.870]This is the most important slide
[00:10:32.060]of this entire presentation on gall midge.
[00:10:34.200]It is the focus for how we look at management
[00:10:35.836]of soybean gall midge and its duration of emergence.
[00:10:39.850]Emergence from last year soybeans.
[00:10:41.240]This is the duration we're talking about
[00:10:42.910]it emerges all year, depending on
[00:10:45.248]which side of the fields you're looking at.
[00:10:48.230]But we checked for volunteer soybeans in our corn fields,
[00:10:51.350]where last year there were soybeans
[00:10:53.071]to ensure we weren't getting a secondary source from those.
[00:10:56.890]But it was much longer than last year.
[00:10:58.790]Our average emergence, as you can see was 25.6 days,
[00:11:02.278]that's almost 10 days longer than 2019.
[00:11:05.570]This means no single management practice will be sufficient
[00:11:09.158]in a high pressure area to control soybean gall midge
[00:11:12.053]You see we range anywhere from 19 days up to 34 days.
[00:11:15.456]That's over a month, I've talked to companies,
[00:11:17.890]they said that nothing on the shelf or in the pipeline
[00:11:20.710]that has that kind of residual activity,
[00:11:22.720]nor would EPA likely register a chemistry
[00:11:25.930]that existed that long in the system.
[00:11:28.770]We'll have to think about gall midge differently
[00:11:31.190]than we're used to with a lot of insects.
[00:11:34.921]This next graph here shows on the x-axis,
[00:11:37.790]the months beginning June 9th
[00:11:40.440]10th was when we saw first emergence,
[00:11:42.420]and its overwintering, adult emergence on the y-axis,
[00:11:45.180]the vertical axis.
[00:11:46.690]You can see we got a quick rise in emergence
[00:11:48.690]across all the sites in Eastern Nebraska.
[00:11:50.663]Then it kind of panned out all the way through to July 15
[00:11:53.579]was our last emergence from last year soybean field
[00:11:56.420]that would be this year's corn for a lot of growers.
[00:12:00.754]What happened was typically within about nine days of that.
[00:12:03.490]We can find larvae and plants pretty easily.
[00:12:05.914]They're present prior to that
[00:12:06.747]they're just not causing enough injury
[00:12:08.061]that they're easy to find within 12 days.
[00:12:10.167]They kinda transition to orange
[00:12:12.360]and within 20 days we can find wilting or dead plants,
[00:12:15.200]in a heavily infested area.
[00:12:17.740]So those give you an idea after adult emergence,
[00:12:20.112]what to look for.
[00:12:21.890]So this pans all the way through to August 10.
[00:12:24.120]Just yesterday, all the yellow you see there now added
[00:12:27.215]to the graph is from this year soybean fields,
[00:12:30.560]across nine sites.
[00:12:32.020]You can see that we've collected over 4300 adults
[00:12:35.340]Last year we collected 1800 adults.
[00:12:37.276]A lot more than what we saw last year.
[00:12:39.930]This is over 800 jars with the presence of adults.
[00:12:44.080]Sometimes we'll pull more than 90 adults from a single jar.
[00:12:46.700]So these numbers are very high on a landscape level,
[00:12:49.900]although we're talking the first hundred feet
[00:12:51.094]in these fields with a lot of significant impact.
[00:12:54.580]So you can see we collected roughly 360 adults yesterday
[00:12:58.540]and we had a peak emergence of a single day of 891 adults
[00:13:02.210]which of course was on a weekend.
[00:13:04.021]Cos they always emerge on a weekend.
[00:13:06.920]Now getting to management.
[00:13:07.753]After going through all this
[00:13:08.586]you can see we face a lot of challenges.
[00:13:10.116]This is a new insect, it's adapting to the system.
[00:13:13.950]This year at the Eastern Nebraska Research
[00:13:15.763]and Extension Center, we evaluated 767 soybean lines.
[00:13:20.510]This is courtesy of NCSRP and United Soybean Board funding
[00:13:24.760]93.7% of those lines were infested.
[00:13:28.370]So we took out a lot to look at next year,
[00:13:30.970]although we'll expand in the areas
[00:13:32.074]where we found potential resistance,
[00:13:34.626]which would be really great for growers,
[00:13:36.910]we need something like this,
[00:13:38.960]wide range of responses anywhere from zero percent.
[00:13:41.400]So meaning the plants were infested but no signs of wilting
[00:13:44.280]to more than 75% of plants were wilting in a single plot.
[00:13:47.710]We're certainly looking at some escapes,
[00:13:48.920]although there are common characteristics
[00:13:50.786]among these varieties that we find are lines
[00:13:54.340]that were found to not be infested.
[00:13:56.259]Eager to look at this next year.
[00:13:58.743]The photo you see on there,
[00:14:00.380]looks like there's one soybean row.
[00:14:02.450]But there's actually a soybean row in front of it
[00:14:04.230]that is nearly 90% dead.
[00:14:06.460]It's overshadowed by the row adjacent,
[00:14:07.566]which we couldn't find any.
[00:14:08.732]These are good signs
[00:14:11.000]for what we might find in the near future.
[00:14:13.830]Management practices were evaluating
[00:14:15.176]14 different chemical control strategies here in 2020.
[00:14:18.940]These are over shots of a plot near Devay
[00:14:21.750]and you can see we're seeing obvious visual differences
[00:14:24.590]with some of our treatments.
[00:14:26.500]I'm not gonna show a lot of that to you today,
[00:14:27.588]because we need to get the yields from these plots,
[00:14:29.544]that's what really matters
[00:14:30.567]cos we're looking at a season long approach,
[00:14:33.240]but certainly we're gonna need a combination of chemical
[00:14:35.710]and cultural control strategies for gall midge.
[00:14:38.140]We know that these strategies applied at the wrong time
[00:14:40.510]say early plantings don't seem to have much effect.
[00:14:44.665]So value of these treatments
[00:14:45.498]will be determined later in the season,
[00:14:47.330]although there's no single plot you see in that photo
[00:14:50.020]that is not injured.
[00:14:51.000]We are not looking at any silver bullets
[00:14:53.220]for soybean gall midge for management this year.
[00:14:56.420]So take home message,
[00:14:57.410]this is a significant pest if it's not in your area,
[00:14:59.610]you definitely need to scout for it,
[00:15:01.320]use you soybeangallmidge.org. for information on scouting.
[00:15:03.844]Its present in several Eastern Nebraska counties,
[00:15:06.270]we've added two already.
[00:15:07.920]Tom Hunt and I are still going through the western side
[00:15:10.520]or western edge of where gall midge is.
[00:15:12.840]Early signs of cultural and chemical strategies
[00:15:14.970]together may reduce pressure,
[00:15:17.020]final yields are needed in order to do that.
[00:15:19.090]For this year, if I was a grower with significant pressure,
[00:15:21.553]I would harvest those fields that are impacted early.
[00:15:24.490]Because one thing that happens with soybean gall midge
[00:15:26.780]is variable pressure in the field
[00:15:28.330]with plants maturing earlier than anticipated,
[00:15:30.890]so those that made it may fling seeds out,
[00:15:33.250]which may cause issues with additional loss in the field.
[00:15:36.548]What about insecticide seed treatments
[00:15:38.844]for managing soybean gall midge?
[00:15:40.113]This is a great question,
[00:15:42.070]especially when we're looking at difficulty
[00:15:43.829]in trying to time our earlier foliar applications.
[00:15:47.610]We've looked at a lot of that this year.
[00:15:48.777]We've looked at Gaucho,
[00:15:51.020]which is imidacloripid in soybean,
[00:15:53.250]we've looked at Cruiser Maxx, which is thiamethoxam.
[00:15:56.810]Those studies are still kind of up in the air
[00:15:58.490]in terms of whether or not
[00:16:00.010]there's an economic benefit to those applications.
[00:16:03.000]But we found with Gaucho
[00:16:04.520]cos we incorporated it into a planting date study,
[00:16:07.680]starting on April 22nd and every 10 days
[00:16:09.933]all the way through to June One,
[00:16:11.980]was that delaying that planting
[00:16:14.220]along with the seed treatment by about may 12,
[00:16:17.330]we started to see a benefit from that seed treatment.
[00:16:19.425]So we started to see differences in larval number,
[00:16:22.330]as well as the number of infested plants,
[00:16:24.700]which is really key.
[00:16:26.490]Unfortunately, those plots don't show that result anymore.
[00:16:29.504]They were so inundated by continued emergence
[00:16:32.770]that site at 26 days of emergence,
[00:16:35.250]they overwhelmed all those treatments.
[00:16:37.450]Maybe this isn't a typical year.
[00:16:39.830]But growers that are thinking about
[00:16:41.190]incorporating seed treatments
[00:16:42.630]for management of soybean garbage,
[00:16:44.530]need to think about delaying planting,
[00:16:46.100]which I know is not a good subject to delay planting,
[00:16:48.720]there's a cost to that,
[00:16:50.570]but then thinking also maybe able to foliar on top of that
[00:16:53.520]around the v2 to try and extend
[00:16:55.220]through that emergence period.
[00:16:57.054]It's not a solid answer yet.
[00:16:58.700]I doubt we see any yield differences
[00:17:00.530]in those studies this year,
[00:17:01.834]because of the continued pressure from those.
[00:17:05.370]Cruiser Maxx is also showing some response.
[00:17:07.540]It's a single planting date.
[00:17:08.590]We can't talk about planting date effects with that one.
[00:17:11.340]Those were incorporated with foliars on top.
[00:17:14.480]That one's up in the air too.
[00:17:15.360]I just suggest after we get through the fall,
[00:17:17.640]we get some yield data.
[00:17:18.940]That's when everybody should follow up with this to say
[00:17:20.850]what really made sense at the end of the season,
[00:17:22.402]given all the pressure this year.
[00:17:24.880]The question is, when scouting,
[00:17:26.710]we're sticking to the four rows of the edge
[00:17:29.130]and that's really just for...
[00:17:30.180]Is this field infested or not
[00:17:31.540]under low population or low presence?
[00:17:34.160]That's different than the severity check
[00:17:36.010]you're talking about which is,
[00:17:37.230]how far into the field does this thing go?
[00:17:40.400]How much should we encourage people scouting
[00:17:42.340]further into a field when looking for soybean gall midge
[00:17:46.230]I've been as far as 600 feet from a field edge
[00:17:49.190]still finding larval presence in plants
[00:17:52.970]and a two to 300 feet I still find dead and wilting plants
[00:17:55.510]in high pressure fields.
[00:17:58.150]We have confusing insects out there,
[00:18:00.490]like dectes stem borer that's present
[00:18:02.220]through a large part of the area,
[00:18:03.530]most of the area where we find soybean gall midge.
[00:18:06.230]Dectes hides itself pretty well
[00:18:08.240]minus a dead trifoliate along the edge of the leaf
[00:18:10.600]you see this wilting trifoliate
[00:18:12.790]that's the key indicator it's present.
[00:18:16.310]The two can be found in the same plant.
[00:18:17.289]We can actually lean into one plant, peel it open
[00:18:19.660]fine dectes and as you get to the bottom of the plant,
[00:18:21.863]you'll find these orange larvae.
[00:18:24.226]What I would suggest as we get further into the field,
[00:18:26.930]it's just almost like you're swimming kind of peel back
[00:18:29.550]the canopy open it up
[00:18:31.020]and if it's all green don't say I'm good.
[00:18:32.903]Lean down the bottom and look at the base of those plants.
[00:18:37.250]I don't know the tricky part
[00:18:39.270]that we face with soybean gall midge
[00:18:40.291]and without a really effective management strategy
[00:18:43.330]is right now we're all looking at gall midge and saying
[00:18:45.380]it's 100 foot pest.
[00:18:46.870]Your losses are limited to 100 feet for the most part
[00:18:50.600]and it's great if it stays there,
[00:18:52.410]but entomologist like myself
[00:18:54.620]and up in Minnesota with Bruce Potter or Aaron Hutchinson
[00:18:58.190]or what about the infested plants that are alive,
[00:19:01.210]but have suffered considerably during the season?
[00:19:04.190]What's their frequency and presence in the field?
[00:19:05.569]Is there a yield reduction with that?
[00:19:08.040]I think this the staggering loss early and then a jump up
[00:19:11.390]in yield suggests we're back to normal.
[00:19:14.190]I don't have a good answer for that.
[00:19:15.830]I think I have some strategies like the image I showed
[00:19:17.900]with those nice green plants amongst dead plants,
[00:19:20.600]that we might be able to better understand that in 2021.
[00:19:23.780]But you really need to do travel across that field.
[00:19:26.937]I understand we're knocking down beans,
[00:19:29.520]it feels like you're taken out part of your field
[00:19:31.810]when you're walking and I definitely feel bad
[00:19:32.650]walking through those fields,
[00:19:34.100]but it is worth the trip to say how far
[00:19:36.460]is this thing into the field
[00:19:37.740]and how concerned do I need to be next year
[00:19:40.180]in terms of its pressure and presence?

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2 - 2020 Soybean Management Field Days - Soybean Gall Midge: Research Updates on a New Pest of Soybean

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