Pesticide Resistance Management 2

Don Lee, Leah Sandall Author

02/12/2019 Added

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[00:00:22.119]This is a cornfield
[00:00:23.620]at the site of Research Farm
[00:00:25.810]at The University of Nebraska.
[00:00:27.300]And it's called the Agricultural Research
[00:00:29.140]and Development Center,
[00:00:30.670]near Mead, Nebraska.
[00:00:32.701]It's a big farm that has a lot of different
[00:00:35.909]research activities going on.
[00:00:38.100]And then this particular experiment
[00:00:40.650]that we're standing next to,
[00:00:43.270]is an experiment to evaluate some
[00:00:45.440]experimental transgenic plants,
[00:00:49.208]and new events that are being developed
[00:00:51.610]for Rootworm Management.
[00:00:53.230]This was actually hand planted,
[00:00:56.010]because these are tent studies to
[00:00:58.520]try to collect every beetle that comes out of these plots.
[00:01:04.010]We planted 10 foot by 4 row plots,
[00:01:07.850]and then replicated different treatments
[00:01:11.730]throughout the study.
[00:01:13.650]The tents are here so that we can,
[00:01:15.560]uh, the Corn Rootworm Beetle is
[00:01:20.390]the adult stage of an insect that feeds on the corn roots.
[00:01:24.190]And when those beetles emerge,
[00:01:26.210]then the tents are surrounding each whole plot
[00:01:29.910]so that we can collect the beetles that come out
[00:01:32.310]over time and record the total emergence period
[00:01:35.690]that are, that they are emerging from each treatment.
[00:01:39.120]We have a dust modified Dustbuster
[00:01:42.490]that they use to collect these beetles with.
[00:01:45.108]They'll systematically lay the tube that
[00:01:48.300]they collect the beetles in, by each tent,
[00:01:51.330]make sure that the treatment number matches the tent number.
[00:01:55.300]And then they'll go in systematically.
[00:01:57.470]Do one tent at a time and collect every beetle
[00:02:01.739]that they can see in a certain period of time in that tent.
[00:02:05.440]And then those beetles then will be labeled.
[00:02:08.950]So we know exactly where they came from,
[00:02:11.490]and we can take those back to the lab
[00:02:13.610]for various other uses.
[00:02:15.910]The tents were placed late vegetative
[00:02:19.320]stage of the corn plants.
[00:02:21.210]Beetles typically emerged at this location
[00:02:23.870]around the 4th of July.
[00:02:25.696]And so these tents were put up in late June,
[00:02:28.750]and beetle emergence has been going on for over a month now.
[00:02:32.320]And so July and most of August
[00:02:35.150]we'll be collecting beetles out of these tents.
[00:02:37.100]In one collection period which
[00:02:38.770]could be a two day collection period,
[00:02:41.270]we can get over 300 beetles per tent.
[00:02:44.760]The total seasonal emergence pattern
[00:02:47.170]that we saw of the Western Corn Rootworm Beetle
[00:02:50.925]from say one tent, for example,
[00:02:53.710]which might be one type of corn.
[00:02:56.240]So that would include the very initial emergence
[00:02:59.935]till the last beetle that emerged late in the season.
[00:03:03.210]So that's called an Emergence Curve.
[00:03:05.550]Most Insect Emergence Curves follow
[00:03:09.170]kind of a bell shaped curve.
[00:03:11.380]And that's typically because
[00:03:13.220]the initial emergence is very low.
[00:03:15.310]And then we usually have a peak emergence period
[00:03:17.250]where we have the highest emergence per day.
[00:03:20.350]And then at the end there's a tail at the end,
[00:03:22.650]where there's very few that come out.
[00:03:24.130]So it ends up being,
[00:03:25.570]it can be a very tight curve,
[00:03:27.040]or it can be very flat
[00:03:28.300]depending on weather and other factors.
[00:03:32.620]We have some treatments,
[00:03:34.200]experimental treatments where emergence is very very low.
[00:03:37.260]I don't think we've had any that we haven't
[00:03:38.979]gotten any emergence from,
[00:03:42.000]but yeah some of the
[00:03:44.290]the new Transgenic Technologies
[00:03:46.900]that provide a high level of control,
[00:03:49.440]will generate a very low number of beetles coming out
[00:03:52.260]compared to a conventional hybrid,
[00:03:54.990]that's not protected genetically against Corn Rootworms.
[00:03:59.455]Those are border rows that were
[00:04:01.310]planted around the experiment.
[00:04:04.600]They are all conventional corn,
[00:04:07.520]that's not protected against rootworms anyway.
[00:04:09.680]There's no soil insecticide or anything else used with them.
[00:04:13.170]And as you can see,
[00:04:15.330]we have a lot of lodging in the corn
[00:04:17.240]the corn has been highly damaged.
[00:04:20.450]The roots have been highly damaged by larvae.
[00:04:23.015]And so when we had wet conditions and high winds,
[00:04:27.660]a lot of those plants were blown over
[00:04:30.276]and they're growing back towards the light now.
[00:04:32.900]So they have kind of a boat or goosenecked appearance.
[00:04:35.706]But they're shorter than the typical corn that's
[00:04:38.400]straight up and down because of that.
[00:04:40.750]Um, so that's probably a worst case scenario
[00:04:44.870]that farmers don't want to see in their fields.
[00:04:47.320]We have a pretty uniform infestation of larvae
[00:04:50.930]all the way through this plot.
[00:04:53.110]And so that we'll have pretty much uniform exposure
[00:04:56.610]across all our treatments to about
[00:04:58.457]the same amount of rootworm pressure.
[00:05:01.200]And we wanted to have a high amount of pressure in here
[00:05:04.220]so that we could really
[00:05:06.729]generate enough beetles from some of the treatments
[00:05:10.140]that are highly effective against rootworms.
[00:05:12.470]So we can really get a good comparison across treatments.
[00:05:17.079](indistinct)
[00:05:22.832](water splashing)
[00:05:27.810]The roots that I'm,
[00:05:28.643]that I have here were taken from a corn rootworm trial.
[00:05:33.130]It was designed to
[00:05:35.480]determine or compare how well
[00:05:38.682]different transgenic plants
[00:05:41.380]and also some of our conventional technologies
[00:05:44.340]such as soil insecticides,
[00:05:46.790]protect corn roots from corn rootworm feeding.
[00:05:49.550]We have a root rating.
[00:05:50.620]There are several root rating systems actually,
[00:05:52.860]where people can go in and quantitatively compare
[00:05:57.490]how much injury is on one plant versus another plant.
[00:06:01.210]And so that's how we compare treatments
[00:06:03.910]and also compare how effective different compounds
[00:06:07.480]or transgenic plants are protecting corn
[00:06:11.210]from rootworm injury.
[00:06:13.640]The root-rating scale we use most of the time
[00:06:15.770]is a zero to three scale.
[00:06:17.880]Based on the number of nodes,
[00:06:20.370]which is the equivalent of 10 roots.
[00:06:23.858]How many of those roots are actually pruned
[00:06:27.120]within one inch, one and a half inches from the plant base?
[00:06:30.840]And because this plant has no pruning
[00:06:34.452]we call pruning to at least one and a half inches
[00:06:37.420]to the base,
[00:06:39.010]then it would be, it would be under a point one root rating.
[00:06:44.320]It's just because it just has feeding scars on it.
[00:06:47.800]No pruning at all.
[00:06:49.260]Extreme contrast is right here.
[00:06:52.003]We have, this is probably a worst case scenario
[00:06:55.440]that you probably won't see in commercial fields too much.
[00:06:59.080]You'll see, you may see a plant here or there like this,
[00:07:02.020]but this is a uniform extreme damage.
[00:07:05.620]This is what rootworms can do to a plant.
[00:07:08.810]And you can see here these dark marks
[00:07:10.710]are actually full nodes of roots
[00:07:12.330]that are completely eaten away by the corn rootworm larvae.
[00:07:16.130]And some of these plants you can see are curved.
[00:07:19.220]It's kind of hard to tell it to tape on,
[00:07:20.670]but they're bowed.
[00:07:22.780]And this is because they lodged in the field.
[00:07:25.230]Hardly any roots holding the plants up when it rained,
[00:07:28.210]and when we had high winds,
[00:07:29.180]it caused the plants to fall over.
[00:07:31.683]And then that's going to directly lead
[00:07:34.340]to yield losses and also cause harvest problems later.
[00:07:37.910]So you'll have harvest losses,
[00:07:39.090]mechanical harvest losses on top of that.
[00:07:42.020]So this really is a good indication of
[00:07:46.530]why a lot of technologies have been developed
[00:07:50.610]to combat corn rootworm injury.
[00:07:52.890]If you have something like this,
[00:07:54.210]if you've ever been a farmer that has
[00:07:56.600]a whole field like this that's gone over,
[00:07:58.490]you'll never forget that.
[00:07:59.700]And so, and it can be really devastating
[00:08:03.030]from a yield standpoint as well.
[00:08:06.500]This plant
[00:08:09.090]in this zero to three system,
[00:08:11.398]every time you have a node removed,
[00:08:13.250]it's one more number higher in the root and system.
[00:08:17.390]So because this one has three nodes
[00:08:18.838]completely eaten within one and a half inches or less,
[00:08:23.969]this would be called a three root rating of three.
[00:08:26.440]And that's the maximum you can get using this scale.
[00:08:30.423]So this is an, an extreme
[00:08:32.673]example of the amount of injury
[00:08:35.360]that you could get from corn rootworms.
[00:08:38.520]In a lot of our trials,
[00:08:39.730]we'll have plants that are in between
[00:08:42.340]the two that I've showed you to varying degrees.
[00:08:45.186]And then you can statistically compare the results
[00:08:49.098]from different treatments by using the scale.

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Pesticide Resistance Management 2

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