Plant Sampling for Disease Diagnostics

Don Lee Author

05/16/2016 Added

66 Plays

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For more information about Oomycete Disease Diagnostics visit: https://ge.unl.edu/oomycete-disease-diagnostics/

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[00:00:10.645]When we're collecting a sample from a field
[00:00:12.888]for a seedling disease problem, one of the first things
[00:00:16.353]we're gonna wanna do is make sure that we've got
[00:00:18.008]something to put that sample in when we collect it.
[00:00:20.924]Typically, in a smaller soybean plant, we're gonna
[00:00:23.294]have a gallon Ziploc bag, or something that
[00:00:25.766]we can put that in.
[00:00:27.177]Make sure you're labeling that bag correctly and including,
[00:00:29.456]you know, all the contact information for
[00:00:31.693]the agronomist or the farmer that you're working with
[00:00:34.279]for that particular field, you know,
[00:00:36.690]where you collected it in the field, even,
[00:00:38.972]some details about, you know, maybe the southeast corner
[00:00:41.669]of the field, for example, just so you can get back
[00:00:44.398]to that site if you needed to go back
[00:00:45.957]for a confirmation later or you needed
[00:00:48.040]more samples collected.
[00:00:49.965]Now, we've identified an area in the field
[00:00:52.323]where we have representative in one of these small pockets
[00:00:56.016]where we're seeing symptoms, really all stages of activity.
[00:00:59.555]So, we've got some dead plants.
[00:01:01.701]We've got some plants on the edge
[00:01:03.226]that are shorter, or less vigorous growing
[00:01:05.748]than our healthy plants.
[00:01:07.322]So, what I like to do is, you know,
[00:01:09.002]include a few of those dead plants.
[00:01:10.714]You don't wanna just include those, though,
[00:01:12.443]because many times those will have many other
[00:01:15.930]secondary fungi colonizing 'em, and that diagnostician
[00:01:19.280]may not be able to work with them.
[00:01:20.976]So, you can include a couple of those, so they can see
[00:01:23.526]the dead plants or that, even if it's pre-emergence,
[00:01:26.480]that decayed seed, and I like to have
[00:01:29.123]three or four plants that are gonna be
[00:01:31.194]reduced in vigor or show some symptoms,
[00:01:33.189]maybe those with cotyledon burning, maybe some
[00:01:35.930]with some leaf wilting or rolling, or a larger plant
[00:01:39.184]with post-emergent damping off, and then
[00:01:41.398]I like to include at least one plant
[00:01:43.269]that's gonna have, or be representative
[00:01:45.023]of what a good looking plant in that field looks like.
[00:01:48.434]Remember that that person doing that diagnosis
[00:01:51.718]is not gonna know the growth stage
[00:01:53.435]of that field or how large a normal plant would look.
[00:01:57.030]So, try to include one of those, as well,
[00:01:58.555]so they can make that comparison.
[00:02:00.443]So, when we're digging plants up, you know,
[00:02:02.911]we're gonna try to capture some soil around
[00:02:05.629]those individual plants.
[00:02:07.229]We're gonna cut that plant out, so we can get
[00:02:09.347]its intact root system, and then we don't have to have
[00:02:12.384]all the soil with that, but we wanna try to
[00:02:14.835]not tear away all of the root mass,
[00:02:18.227]so leaving some soil in the bag, that's gonna be fine.
[00:02:21.336]So, we're digging that plant up, and then
[00:02:24.347]for analysis, the diagnostician can easily take that out.
[00:02:27.600]So having some soil, that's fine,
[00:02:29.158]but we're gonna put several of those in there.
[00:02:31.479]So, we're gonna go ahead, and we're gonna collect
[00:02:33.200]several plants that have reduced vigor or growth.
[00:02:37.297]Here's another seedling which you can see
[00:02:38.992]isn't as merged as well.
[00:02:41.146]We're gonna take that plant and just pull it out gently,
[00:02:44.423]where we not removing a lot of the root system.
[00:02:46.210]Just have the root mass intact.
[00:02:47.693]We're gonna put that in the bag, as well.
[00:02:50.009]We're just gonna continue here to try to get
[00:02:52.158]some other plants that have those same kind
[00:02:54.679]of symptoms where we're looking at,
[00:02:56.784]some cotyledon injury and less vigor, and there again,
[00:02:59.706]we've just a root mass, small root mass,
[00:03:01.637]put that in there, and then, too, we're gonna also
[00:03:04.559]take a step and try to find some plants
[00:03:06.441]that look representative of what the larger plants
[00:03:10.394]are that we have in the field.
[00:03:11.823]So, in this particular case, we've got
[00:03:13.262]a couple plants here that have some
[00:03:14.386]nice bright green cotyledons, and we're gonna take
[00:03:16.874]those and pick those out, and just take
[00:03:19.727]a couple of those just to show, you know,
[00:03:22.245]what a better looking plant actually looks like
[00:03:25.075]in this particular field.
[00:03:26.650]So, we've got our healthy plants.
[00:03:28.133]We can put those in a separate bag, possibly,
[00:03:29.996]or the same bag.
[00:03:31.301]Just so that you're able to identify
[00:03:33.499]the difference when you share that with the diagnostic lab.
[00:03:36.307]So, we've got some diseased plants,
[00:03:38.494]some dead plants, and then we've got
[00:03:40.576]a couple healthy plants, as well, and then
[00:03:42.960]what we're gonna wanna do with this is make sure that
[00:03:45.163]that sample, we're gonna keep it nice and cool.
[00:03:48.915]We're not gonna wanna let that clear plastic bag
[00:03:50.701]in the sun, because that really gets hot, and put that
[00:03:53.527]in a cooler if you can, and if you have to,
[00:03:56.126]keep it in a refrigerator overnight, and then
[00:03:58.967]get that to your diagnostic center
[00:04:00.781]or diagnostic lab for analysis.

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Plant Sampling for Disease Diagnostics

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