9 - 2021 South Central Ag Lab Field Day - Update on Frogeye Leaf Spot

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10/14/2021 Added

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9 - 2021 South Central Ag Lab Field Day - Update on Frogeye Leaf Spot - Asha Mane, Graduate Student

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[00:00:07.880]Hi everyone. I'm Asha Mane.
[00:00:09.890]I'm a PhD student at the UNL Department of Plant Pathology.
[00:00:14.330]I work with extension plant pathologist, Tamra Jackson, since and today,
[00:00:19.070]I'm going to give a brief update on frogeye leaf spot of soybean.
[00:00:24.020]This is a summary of what we have talked about during Scottfield
[00:00:28.760]day on 28,
[00:00:30.290]July, 2021 for the leaf spot of Serbian is a disease
[00:00:35.210]caused by fungal pathogen cyclospora. So China,
[00:00:39.170]if you're scouting your soybean fields for frogeye leaf spot,
[00:00:42.320]which is also known as FLS,
[00:00:44.480]what you should be looking at is leaves that have spots
[00:00:49.310]with Dan or gray colored lesions.
[00:00:52.790]They have dark red or purple border and a very
[00:00:57.350]characteristic black spot at the center.
[00:01:01.340][inaudible]
[00:01:02.510]that causes FLS disease of Serbian likes optimal temperature of
[00:01:07.490]77 to 86 degrees Fahrenheit.
[00:01:10.970]This fungus really likes UBIT conditions and frequent rain or
[00:01:15.740]irrigation can add to the severity of the disease.
[00:01:20.390]What you're able to see in this picture is a Serbian leaf that has frogeye leaf
[00:01:25.010]spot lesions, but Dwight scouting.
[00:01:30.830]It is also important to remember that some other diseases may look like FLS.
[00:01:36.050]One of the examples is fallow stick that leaf spot.
[00:01:40.520]In case of fantastical leaf spot,
[00:01:42.410]you will see gray color lesions similar to those of FLS,
[00:01:46.760]but fantastical leaf spot will have black spots on these
[00:01:51.290]lesions, which differentiate them from FLS.
[00:01:55.130]So if you are able to see this black spots on gray lesions, that is fantastic,
[00:01:59.690]the leaf spot and not frogeye leaf spot in case of
[00:02:03.980]FLS. As I said before,
[00:02:05.750]you will see gray color legions with dark border and a very
[00:02:10.250]characteristic black spot at the center,
[00:02:14.600]which makes them look like an aisle, a frog.
[00:02:17.330]So you can see in this picture here,
[00:02:19.580]how the lesions of FLS compared to an eye of a frog look very similar.
[00:02:24.650]So when you're scouting your soybean field for FLS,
[00:02:28.070]this is something that you may remember moving on to
[00:02:32.660]management strategies to control FLS application of foliar.
[00:02:37.610]Fungicides has been a very common management strategy,
[00:02:42.020]but when you're making your fungicide applications,
[00:02:45.140]please remember that the fungicide application has to be done at the right
[00:02:49.670]stage.
[00:02:50.720]And that right stage is from R three to R five R three is
[00:02:55.610]beginning of bot development. And our five is beginning of C development.
[00:03:01.540]Another important note while making foliar fungicide application is
[00:03:06.430]fungicide should be applied only after scouting and only if the fungicide
[00:03:10.900]application is needed. In case of foliar fungicides,
[00:03:16.120]there are three groups of foliar fungicides that are typically used to control
[00:03:21.100]FLS.
[00:03:22.720]The most important is qui or strobilurin group of fungicides from
[00:03:27.460]group 11,
[00:03:29.080]DMI fungicides from group three and SDHI fungicides from
[00:03:33.820]group seven,
[00:03:37.150]historically group 11 or strawberry group of fungicides were most
[00:03:42.130]effective for controlling FLS.
[00:03:44.800]But the current issue is that qui fungicide resistance has
[00:03:49.570]already been reported in [inaudible] causing this disease.
[00:03:55.210]In this map,
[00:03:55.930]you can see various reports of fungicide resistance in FLS pathogen,
[00:04:00.970]across United States. In this map,
[00:04:04.510]you can see a color coding that shows reports on qui fungicide
[00:04:09.370]resistance from ER 2010 to 2017 in
[00:04:14.170]14 different states around two 40 counties in this 14 different
[00:04:19.120]states reported to have QR fungicide resistance.
[00:04:23.020]Later in 2018,
[00:04:25.210]the distance was also reported in four counties in South Dakota
[00:04:31.120]in 2019.
[00:04:34.120]Do I find you resistance was reported in our neighboring state, Iowa,
[00:04:39.400]the 73 different fields in 51,
[00:04:42.170]Iowa counties were reported to have qui fungicide resistance.
[00:04:46.960]And now for the most important update for our state,
[00:04:51.460]Nebraska Jua fungicide resistance has already been reported.
[00:04:55.750]It was reported for the first time in year 2019. If you look at this map,
[00:05:00.760]you can see 10 counties that are highlighted yellow.
[00:05:05.230]In 2019,
[00:05:06.610]we conducted a small survey where samples from these 10
[00:05:11.350]counties were collected and screen for QR resistance.
[00:05:16.000]And 98% of the collected samples were found to be resistant.
[00:05:20.770]That really shows that the resistance is severe. At this point,
[00:05:25.450]we didn't really know the status in other counties.
[00:05:30.280]In 2020,
[00:05:31.300]we expanded the survey and collected samples from
[00:05:35.830]48 Nebraska counties.
[00:05:39.850]There's a map on the left where you can see 48 counties highlighted
[00:05:44.680]in blue. We screened 1 28 fields in this 48 counties.
[00:05:50.140]And if you compare this highlighted area with the map on the right,
[00:05:55.600]you can see that the sample collection covered most of the soybean
[00:06:00.380]producing region in the state of Nebraska, Scott,
[00:06:05.830]the screen in the preliminary analysis,
[00:06:09.550]we screen eight samples from each of these 48 counties and
[00:06:14.560]found that all of those samples had qui fungicide
[00:06:18.760]resistance.
[00:06:20.290]This really shows the severity and the widespread of qui fungicide
[00:06:24.730]resistance in the state of Nebraska
[00:06:28.660]since the fungicide resistance had, is now confirmed,
[00:06:33.130]we would recommend some updates on frogeye leaf spot disease management.
[00:06:37.870]It is recommended to use an integrated disease management plan.
[00:06:42.790]It is highly recommended to select frog registered.
[00:06:46.120]So I've been varieties and crop rotation whenever possible
[00:06:51.130]by doing application of foliar fungicides. As I mentioned before,
[00:06:55.570]foliar fungicide should be applied only after scouting.
[00:06:59.320]And since now we have resistance reported in group 11
[00:07:04.330]or strobilurin fun group of fungicides.
[00:07:07.180]We recommend that you use a mixture of fungicides rather than using a single
[00:07:11.950]class of fungicides also while making your application be sure to
[00:07:16.630]follow all the pesticide label instructions,
[00:07:19.780]because that will ensure the efficacy of the fungicides.
[00:07:26.170]Now, to give you a brief idea on the current status of different
[00:07:31.930]products or foliar fungicides, and their efficacy in the stable,
[00:07:36.430]you can see that three different colors on the left that shows
[00:07:42.190]group 11, fungicides group seven, fungicides and group three fungicides.
[00:07:47.500]I want you to focus on the group 11 fungicides that is had in yellow color.
[00:07:52.810]And if you see the products from group 11 and that efficacy against
[00:07:57.610]frogeye leaf spot, they clearly show poor efficacy,
[00:08:01.270]which means that group 11 fungicides are no longer useful for frogeye leaf spot
[00:08:06.010]management do group three and group seven fungicides show
[00:08:10.800]some efficacy against the disease using them on using
[00:08:15.520]only group seven or group three. Fungicides will not be efficient now,
[00:08:20.170]but just looked at the efficacy of foliar fungicides when used a single
[00:08:24.910]product. Now, if you look at the efficacy of foliar fungicides,
[00:08:29.290]when we use a mixed class of mixed class of products,
[00:08:34.480]if you see group seven and group three used together,
[00:08:39.430]they, you,
[00:08:40.120]they show very good efficacy against foliar disease,
[00:08:45.340]frogeye leaf spot. If you use a combination of group 11,
[00:08:49.960]seven and three, they also show very good efficacy against frogeye leaf spot.
[00:08:56.400]In these two tables, I gave just a summary of,
[00:08:59.880]if you could see a foliar fungicides against frogeye leaf spot,
[00:09:03.120]but if you would like to know more information on fungicide products and that
[00:09:07.770]efficacy, I would recommend to refer to this article.
[00:09:13.470]There's a QR code on this slide that you can use the QR code scanner to
[00:09:18.390]scan this.
[00:09:19.140]And it should take you to an article from crop protection network.
[00:09:24.000]The article discusses fungicide efficacy for control of Serbian
[00:09:28.770]foliar diseases. So that includes not just frogeye leaf spot,
[00:09:32.430]but some other foliar diseases of soybean.
[00:09:35.550]And if it Cassie or foliar fungicides against those against those
[00:09:40.080]disease, you can either use this QR code,
[00:09:43.200]or there is a text highlighted yellow.
[00:09:46.260]You can use that text in your browser,
[00:09:49.950]and that will directly take you to this article from crop protection network.
[00:09:56.130]Apart from that,
[00:09:56.910]you can find more resources on crop watch or market John John,
[00:10:02.190]or if you have any questions related to frogeye leaf spot or fungicide
[00:10:05.760]resistance, you can reach out to UNL diagnostics clinic or Dr.
[00:10:10.230]Tamra Jackson's Sims at UNL extension. Thank you.

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9 - 2021 South Central Ag Lab Field Day - Update on Frogeye Leaf Spot

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