10 - 2020 South Central Ag Lab Field Day

Mike Kamm Author

12/04/2020 Added

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2020 South Central Ag Lab Field Day

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[00:00:04.550]Hello, I'm Asha Mane.
[00:00:06.200]I'm currently doing my PhD at the University of Nebraska-Lincoln.
[00:00:10.130]I joined the Department of Plant Pathology.
[00:00:12.350]I work with Extension plant pathologist, Dr.
[00:00:15.080]Tamra Jackson Ziems and associate professor Dr. Sidney Everhart.
[00:00:19.790]Today, I'm going to give you an update on a very important disease.
[00:00:23.420]Frogeye leaf spot of soybean.
[00:00:27.170]This disease is also known as FLS.
[00:00:30.470]FLS is currently developing in the fields in Nebraska and becoming
[00:00:35.360]more severe.
[00:00:37.430]This is a good time to scout the field for the disease and know whether the
[00:00:41.600]fungicide application is needed.
[00:00:44.450]If you have seen FLS in your fields last year,
[00:00:47.540]there's a good chance that you will see the disease this year as well.
[00:00:52.190]FLS is caused by a fungus prosperous vagina,
[00:00:55.610]and the disease has already been reported in most Serbian producing areas of the
[00:01:00.260]United States.
[00:01:03.500]You can see an leaf image on the right that shows symptoms of frogeye leaf
[00:01:08.360]spot. I would show a closer look of this later,
[00:01:12.620]but what you can see here is tan or gray color legions
[00:01:17.180]with red or purple border.
[00:01:20.960]You will see this symptoms mostly on the leaves in the upper canopy,
[00:01:25.580]but the symptoms can also be seen on seed STEM pot.
[00:01:32.390]A fellow severely affects soybean.
[00:01:35.300]When weather conditions are formed humid that frequent rain or
[00:01:40.070]education optimal temperature of 77 to
[00:01:44.840]86 degree Fahrenheit is favorable for the disease.
[00:01:48.890]And if these weather conditions persist that might make the disease
[00:01:53.660]CVR
[00:01:56.960]By scarping for frogeye leaf spot,
[00:01:59.960]what you will see is the spots.
[00:02:03.290]Initially look like water spots, which later turned into lesions.
[00:02:09.260]When the lesions are younger, they're smaller in size,
[00:02:13.040]but as they grow older, they get bigger
[00:02:17.900]by scouting for FLS.
[00:02:20.420]It is also important to know that some other Serbian diseases may look like
[00:02:24.890]FLS. One of the examples is Phyllosticta. The leaf spot,
[00:02:30.890]this disease is caused by a different fungus Phyllosticta.
[00:02:36.080]As you can see in the image on the left Phyllosticta,
[00:02:39.590]the leaf spots are also done or create in color.
[00:02:43.520]They have dark borders and are circular to oval in shape,
[00:02:48.920]but what makes Phyllosticta l leaf spot different is once these
[00:02:53.720]legions mature,
[00:02:55.580]they show black specks in the middle of the spot.
[00:02:59.680]This black specks are fungal reproductive structures,
[00:03:03.640]and these will not be seen in case of FLS.
[00:03:07.780]When you look at frogeye leaf spot,
[00:03:09.550]you will see tan or gray Legion with red or purple border,
[00:03:14.920]and a very characteristic black spot at the center,
[00:03:18.580]which gives this parts and appearance of an eye for frog.
[00:03:24.400]Moving on to management strategies,
[00:03:27.640]the general management strategies for FLS are selection of resistant
[00:03:32.410]varieties.
[00:03:33.790]Avoiding growing continuous Serbian grew up an application of foliar. Fungicides
[00:03:40.120]foliar fungicide application should be done only after scouting and it should
[00:03:45.070]be done at a stage, which is most effective for the efficacy.
[00:03:50.890]Fungicide application is most effective when it is done at reproductive stage
[00:03:55.870]are three to reproductive stage R5 and R3 is beginning
[00:04:00.790]of seed development. And R5 is beginning of pod development
[00:04:07.630]For the fungicide treatment of frogeye leaf spot.
[00:04:10.090]There are three classes of fungicides typically used on soybean.
[00:04:14.680]First is q0i or more commonly known as strobilurin group of
[00:04:19.210]fungicides.
[00:04:20.560]The belong to frat group 11 DMI fungicides belong to
[00:04:25.330]FRAC group three and SDHI fungicides that belong to group seven.
[00:04:31.630]If you wish to know more information about this,
[00:04:34.270]we should definitely refer to the disease management section from 2020 guide
[00:04:39.070]for VI disease and insect management in Nebraska.
[00:04:43.960]Another very useful resource for you could be an article that was published in
[00:04:48.610]crop protection network.
[00:04:50.560]This article discusses fungicide efficacy for control of serving
[00:04:55.450]foliar diseases. If you use the given QR code,
[00:04:59.770]or if you go to the given URL,
[00:05:01.810]you will find a link to this article in case you do not have access to this
[00:05:06.190]article. Don't worry about it. Because later in the stock,
[00:05:09.280]I will talk in detail about the fungicide efficacy,
[00:05:14.920]Looking at the foliar fungicides for FLS treatment.
[00:05:19.060]I already mentioned the three classes that are typically used,
[00:05:23.530]but I find the sites from group 11 are historically known to be most
[00:05:28.270]effective to treat FLS.
[00:05:31.390]But the issue is the resistance is becoming more common
[00:05:35.800]development of resistance reduces the efficacy of the fund.
[00:05:38.930]Sites.
[00:05:42.570]QR fungicide resistance has other dip in the report tech in the
[00:05:46.650]United States. You can see in this map that from ER,
[00:05:50.520]2010 to 2072 40 counties from
[00:05:55.080]14 different States reported qui fungicide resistance
[00:06:01.370]in late 2018,
[00:06:03.950]the distance was confirmed in four counties in Southeast South Dakota
[00:06:09.200]in the state of Iowa samples from 73 fields in
[00:06:13.850]51 counties were found to be resistant to q0i fungicides
[00:06:20.630]and for the most important update of the day in year 2019,
[00:06:25.580]Qoi fungicide resistance was confirmed for the first time in the state of
[00:06:29.870]Nebraska,
[00:06:31.970]we conducted a small survey where FLS samples were collected from 10
[00:06:36.530]Nebraska counties.
[00:06:38.840]These 10 counties are highlighted yellow in this map.
[00:06:43.130]98% of the collected samples were found to be resistant to qui
[00:06:47.930]fungicides.
[00:06:51.200]Since these were the only 10 counties from where samples were collected,
[00:06:56.240]we currently do not know how widespread this problem is in Nebraska,
[00:07:01.520]but to avoid the possible widespread drugs should update
[00:07:06.410]their management strategies.
[00:07:09.080]Draws should opt for an integrated management plan,
[00:07:12.050]which includes selection of resistant varieties,
[00:07:17.660]practicing crop rotation, whenever possible,
[00:07:21.920]an application of foliar fungicides
[00:07:25.790]to give you an update on fungicide efficacy for control of soybean foliar
[00:07:30.050]diseases. You can see this table,
[00:07:33.710]this table is taken from the fungicide efficacy resource I earlier talked about
[00:07:39.710]though. There's a lot of information on this table.
[00:07:41.870]I'm going to highlight the information that is relevant for you.
[00:07:46.790]The QA or strobilurin group of fungicides,
[00:07:49.760]when used alone for treatment of FLS, they showed poor efficacy.
[00:07:55.040]Also the SDHI group of fungicides when used alone to treat FLS short,
[00:07:59.840]poor efficacy,
[00:08:01.160]which means these group of fungicides are no longer efficient for a treatment.
[00:08:08.920]Bye.
[00:08:09.220]DMI group of fungicides and MBC twofer nets when used
[00:08:14.020]alone showed fair, good, or very good efficacy.
[00:08:18.340]So this could be a better option.
[00:08:23.260]Looking at the efficacy of mixed mode of action fungicides,
[00:08:28.060]there are different products available and this product show fair,
[00:08:33.040]good, or very good efficacy.
[00:08:36.790]Some of the mixed mode of action fungicides are now available in a combination
[00:08:40.840]of three, or you can also make your own mixes,
[00:08:45.670]but if you are making your own combinations,
[00:08:48.130]be sure of following the pesticide level.
[00:08:50.380]Options.
[00:08:53.500]If you'll find it in, how do you,
[00:08:55.380]if there is a fungicide resistance in your field,
[00:08:58.470]you can submit the Phyllis samples to UNL diagnostics clinic.
[00:09:03.090]You can use the given QR code or visit the given URL,
[00:09:07.830]which will provide all the information on how to collect the samples and how to
[00:09:12.630]submit them to UNL diagnostics clinic.
[00:09:17.520]At the UNL department of plant pathology,
[00:09:20.040]we are currently developing a rapid test to detect fungicide resistance to
[00:09:24.900]the qui group. This test is currently in progress.
[00:09:29.400]The samples that will be collected now will be processed in winter.
[00:09:34.530]But once this test is established,
[00:09:36.480]we will be able to perform it in two to three hours.
[00:09:40.470]We will be able to perform this test to both in lab and in field.
[00:09:44.790]And this test is going to allow us the timely suggestion for the fungicide
[00:09:48.660]selection. If you wish to know more information,
[00:09:53.580]these are some very useful resources you can find online if you want to
[00:09:58.380]stay updated on disease management in Nebraska, do follow us on Twitter.
[00:10:04.650]Thank you.

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10 - 2020 South Central Ag Lab Field Day

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