The annual UW Agronomy, Pest Management and Soil, Water, and Nutrient Management meetings are moving to a new format this year and will be offered as a single day-long program. Two in-person sessions as well as a virtual option will be offered. In-person sessions in Green Bay and La Crosse will follow the same agenda. The virtual option will follow a similar but abbreviated agenda.
This year’s program will be focused on the theme of “Achieving a Positive Return on Investment in an Era of High Input Costs (a.k.a Small steps, Big change).” The meetings will present the latest information on agronomic, pest, and nutrient management research coming out of UW with a lens to on-farm application.
For details and to register for the event, please CLICK HERE or scan the QR code in the attached flyer. We are looking forward to seeing you and kicking off a busy winter meeting season!
https://badgercropdoc.com/wp-content/uploads/sites/5/2022/11/Screenshot-2022-11-22-at-8.11.53-PM.png13721062damonsmithhttp://badgercropdoc.com/wp-content/uploads/sites/5/2018/05/bcd-color-300x153.pngdamonsmith2022-11-23 02:25:022022-11-23 02:26:152022 Badger Crops and Soils Update Meetings
Damon Smith, Extension Field Crops Pathologist, Department of Plant Pathology, University of Wisconsin-Madison
Roger Schmidt, Nutrient and Pest Management Program, University of Wisconsin-Madison
Rain, and the return of more humid weather, has meant that risk of tar spot of corn and white mold of soybean has increased over the past week. Now is the time to think about your in-season management plan for both of these diseases. Let’s dig in a bit on what the risk looks like for each disease.
This week we added Fond du Lac County to the tar spot map (Fig. 1). We also continue to see tar spot slowly increasing in plots and production fields on the Arlington research station. Looking back at our records from last season, we are tracking almost identically with what happened last year. I know folks think it is dry, but the tar spot fungus doesn’t care. It might move slow in these conditions, but the elevated humidity provides adequate leaf wetness for the disease to slowly progress. Should it start raining more regularly I expect the disease to pick up speed.
Corn is rapidly approaching (if not already at) the optimal window of opportunity (VT-R3) for spraying fungicide to control tar spot. Given the high risk for tar spot across much of the state (Fig. 2), now is the time to call in that fungicide application if you are planning on it. Given the possible constraints on locating a custom applicator, getting the order in earlier than later may ensure application of fungicide by the R3 corn growth stage. Get out and scout, scout, scout!
Figure 2. Tar Spot Risk for Wisconsin on July 21, 2022
White Mold of Soybean
White mold risk has increased from reasonably low last week, to mostly moderate across the state, this week (Fig. 3). Risk trends are also increasing, indicating that weather is continuing to become more favorable for white mold development. As we approach the R3 soybean growth stage, it will be important to make a decision on fungicide application, especially if you haven’t already applied a fungicide. If rain moves in over the next 7-10 days, expect risk to continue to increase. In irrigated fields we have been able to find apothecia (the mushroom-like structure that produces spores that infect soybean). This corroborates the increased risk we are seeing even in non-irrigated fields.
Figure 3. White mold risk in Wisconsin for July 21, 2022.
The Field Prophet Tool
For those who like all of their disease prediction tools in one place you might check out the Field Prophet versionof the Tarspotter and Sporecaster apps. This tool consolidates all of our disease prediction tools into one convenient tool. The app also allows for true 7-day forecasting and will display 7-day trends to better inform your disease management decisions. Field Prophet, Inc is a startup company supported by UW-Madison and uses science-based information and the same models as Tarspotter and Sporecaster to deliver informative tools for agriculture clientele. You can also download and use Field Prophet for free for the next 6 months! You might find this tool as a handy alternative to Tarspotter and Sporecaster.
https://badgercropdoc.com/wp-content/uploads/sites/5/2022/07/IMG_7763-scaled.jpg25601830damonsmithhttp://badgercropdoc.com/wp-content/uploads/sites/5/2018/05/bcd-color-300x153.pngdamonsmith2022-07-22 02:52:522022-07-22 02:52:52Wisconsin Corn and Soybean Disease Update and Forecast – July 21, 2022
Damon Smith, Extension Field Crops Pathologist, Department of Plant Pathology, University of Wisconsin-Madison
Roger Schmidt, Nutrient and Pest Management Program, University of Wisconsin-Madison
Weather over the last week has been generally drier with milder temperatures in most of Wisconsin. Isolated storms have occurred and periods of leaf wetness have prevailed. So what does that mean for important plant diseases of corn and soybeans? Let’s break that down.
As noted last week we found tar spot in Columbia county Wisconsin, which was the first report for 2022. This week we add Dane County to the list (Fig. 1). Tarspotter risk has remained high for much of the state over the last week due to milder temperatures and periods of leaf wetting events. It is important to note that conditions favorable for tar spot development are different than those for white mold in soybean. For white mold rain, more sustained wetting events, and cooler temperatures are required (see below). As of today (July 14, 2022) tar spot risk remains high or elevated for most of the state (Fig. 2). Over the next week the forecast is putting us a bit drier and hotter. Thus, the tar spot risk could continue to decline. However, remember that tar spot will continue to show up due to favorable weather 2 or more weeks back. The tar spot pathogen has a long incubation period (time from infection to tar spot appearance). Thus, you shouldn’t be surprised in finding tar spot at low levels over the next week. So should you spray fungicide now? If you can, wait until at least the VT (tasseling growth stage). The evidence is strong that the optimum window to spray fungicide to control tar spot is between the VT and R3 (milk) growth stages. Spraying before VT might leave corn plants vulnerable to a late-season tar spot increase. Thus, if you spray before VT, you might need to come back with a second application of fungicide closer to the R3 growth stage. For guidance on when/if to spray fungicide to manage tar spot, see my previous article.
Figure 2. Tar spot risk for Wisconsin on July 14, 2022.
White Mold of Soybean
White mold risk remains generally low and is dropping for most of the state of Wisconsin (Fig. 3). This is not surprising as temperatures have remained moderate with drier conditions. Based on the current risk and the 7-day forecast, fungicide applications can be held back. Folks should pay attention to the weather and Sporecaster risk as the crop moves into full bloom and early pod development. In recent years we have seen white mold risk increase during the late bloom time necessitating a fungicide application around the R3 growth stage. I would expect this same scenario to set up in 2022 in at least a portion of Wisconsin. Folks should monitor this situation carefully as we move ahead over the next 2 weeks. For more information on white mold and making the fungicide spray decision, see this previous article.
Figure 3. White mold risk for Wisconsin for July 14, 2022.
The Field Prophet Tool
For those who like all of their disease prediction tools in one place you might check out the Field Prophet versionof the Tarspotter and Sporecaster apps. This tool consolidates all of our disease prediction tools into one convenient tool. The app also allows for true 7-day forecasting and will display 7-day trends to better inform your disease management decisions. Field Prophet, Inc is a startup company supported by UW-Madison and uses science-based information and the same models as Tarspotter and Sporecaster to deliver informative tools for agriculture clientele. You can also download and use Field Prophet for free for the next 6 months! You might find this tool as a handy alternative to Tarspotter and Sporecaster.
https://badgercropdoc.com/wp-content/uploads/sites/5/2022/07/IMG_6785-scaled.jpg25601920damonsmithhttp://badgercropdoc.com/wp-content/uploads/sites/5/2018/05/bcd-color-300x153.pngdamonsmith2022-07-14 15:42:172022-07-14 15:43:58Wisconsin Corn and Soybean Disease Update and Forecast - July 14, 2022
Damon Smith, Extension Field Crops Pathologist, Department of Plant Pathology, University of Wisconsin-Madison
Shawn Conley, Extension Soybean and Small Grains Agronomist, Department of Agronomy, University of Wisconsin-Madison
Roger Schmidt, Nutrient and Pest Management Program, University of Wisconsin-Madison
Paul Mitchell, Extension Economist, Agricultural and Applied Economics, University of Wisconsin-Madison
Figure 1. Apothecia, a small mushroom-like structure of the white mold fungus that give rise to spores, which infect soybean flowers.
In Wisconsin, the first couple of weeks of July brings us a heightened awareness of white mold in soybeans, and its management. The 2021 season in Wisconsin resulted in some pockets of white mold in the state. However, now is not the time to be complacent. If the weather becomes conducive in 2022, the situation could be much different than last year.
Remember that the white mold fungus infects soybeans through open and senescing flowers, by spores that are born from small mushroom-like structures called apothecia (Fig. 1). Remember that if the bloom period gets extended due to cool weather, this can lead to an extended window for infection by the fungus. Often cool weather is a double whammy as it is good for the white mold fungus and slows down soybean crop development, thereby extending bloom.
While conditions have been hot and dry in parts of the state, we are seeing cooler and wetter conditions over the last week. The white mold situation can change rapidly based on weather, thus anticipating favorable conditions for white mold, can help you protect your soybean crop.
Predicting White Mold
The flowering growth stages are a critical time to manage white mold in-season. You can view a fact sheet and video on the subject. As you probably know, timing in-season fungicide sprays at the correct time during the soybean bloom period can be extremely difficult. To help solve this decision-making issue, models were developed at the University of Wisconsin-Madison in conjunction with Michigan State University and Iowa State University to identify at-risk regions which have been experiencing weather favorable for the development of white mold apothecia. These models predict when apothecia will be present in the field using combinations of 30-day averages of maximum temperature, relative humidity, and wind speed. Using virtually available weather data, predictions can be made in most soybean growing regions. To facilitate precise predictions and make the model user-friendly, we use the Sporecaster smartphone application for Android and iPhone and also the Field Prophet app for iPhones.
Figure 2. Sporecaster predictions for selected non-irrigated locations in Wisconsin for July 8, 2022.
The purpose of the smartphone app is to assist farmers in making early season management decisions for white mold in soybean. The best time to spray fungicides for white mold is during flowering (R1 and R3 growth stages) when apothecia are present on the soil surface. If you have trouble growth-staging soybeans, here is a helpful guide on correctly identifying soybean growth stages.
Sporecaster uses university research to turn a few simple taps on a smartphone screen into an instant forecast of the risk of apothecia being present in a soybean field, which helps growers predict the best timing for white mold treatment during the flowering period.
University research has indicated that the appearance of apothecia can be predicted using weather data and a threshold of percent soybean canopy row closure in a field. Based on these predictions and crop phenology, site-specific risk values are generated for three scenarios (non-irrigated soybeans, soybeans planted on 15″ row-spacing and irrigated, or soybeans planted on 30″ row-spacing and irrigated). Though not specifically tested we would expect row-spacings of 22 inches or less to have a similar probability response to fungicide as the 15 inch row-spacing.
The Sclerotinia apothecial models that underlie the Sporecaster prediction tool have undergone significant validation in both small test plots and in commercial production fields. In 2017, efficacy trials were conducted at agricultural research stations in Iowa, Michigan, and Wisconsin to identify fungicide application programs and thresholds for model implementation. Additionally, apothecial scouting and disease monitoring were conducted in a total of 60 commercial farmer fields in Michigan, Nebraska, and Wisconsin between 2016 and 2017 to evaluate model accuracy across the growing region. Across all irrigated and non-irrigated locations predictions during the soybean flowering period (R1 to early R4 growth stages) were found to explain end-of-season disease observations with an accuracy of 81.8% using the established probability thresholds now programmed in the app. We have made additional improvements for 2022, to further refine accuracy. So if you have used Sporecaster before, you might want to check the version in the “Help and Info” button to be sure you have version 1.41 of Sporecaster. If you want to learn more about the science of Sporecaster, check out the embedded video below.
Not only can users run predictions of risk during the soybean bloom period for any field, you can also set up visual maps to look at multiple sites simultaneously. An example for the state of Wisconsin can be found in figure 2, which represents risk for July 8, 2022 for non-irrigated soybeans. Currently, if soybeans are flowering, risk is moderate to low in much of Wisconsin for non-irrigated soybeans, due to the recent hot and dryer weather. In the north-eastern portions of the state, risk for flowering soybeans is higher due to cooler conditions and more frequent rain events that have occurred there. Check back to this blog regularly as I will post maps like these with interpretation of risk for Wisconsin as we move through the season.
What to Spray for White Mold?
If you have decided to spray soybeans for white mold, what are the best products to use? Over the last several years we have run numerous fungicide efficacy trials in Wisconsin and in conjunction with researchers in other states. In Wisconsin, we have observed that Endura applied as a single application at 8 oz between the R1 and R2 growth stage performs well. Other fungicide options also include Omega and Proline. You can view results of past fungicide evaluations for Wisconsin by CLICKING HERE.If you would like to run tailored estimations of return on investment for various fungicide programs, you can use another smartphone application called Sporebuster.
What is Sporebuster?
When a fungicide application is needed to control white mold in soybeans, Sporebuster can help determine a profitable program. You enter your expected soybean price, expected yield, and treatment cost. Sporebuster instantly compares ten different treatment plans at once to determine average net gain and breakeven probability of each. You can mark, save and share by email, the best plans for your farming operation.
The purpose of Sporebuster is to assist soybean farmers in making a fungicide program decision that is profitable for their operation. Sporebuster is meant to complement Sporecaster. Once Sporecaster recommends a fungicide application, Sporebuster can be used to determine a profitable program.
Information that drives Sporebuster is based on research from 2009-2016 from across the upper Midwestern US. Statistical models were developed based on these data that included white mold pressure and yield response from fungicide for 10 common fungicide programs. Due to recent changes in the markets, be sure to manually adjust the cost of the product you are interested in, so that the tool returns an accurate estimate of return on investment. My advice is to call local suppliers and see what products you can get and what the per acre cost will be to get the application done. Details about the research behind Sporebuster can be found by CLICKING HERE.
To watch an in-depth video on white mold management, CLICK HERE.
To find more information on white mold, view a web book from the Crop Protection Network, CLICK HERE.
Scientific References
Willbur, J.F., Fall, M.L., Blackwell, T., Bloomingdale, C.A., Byrne, A.M., Chapman, S.A., Holtz, D., Isard, S.A., Magarey, R.D., McCaghey, M., Mueller, B.D., Russo, J.M., Schlegel, J., Young, M., Chilvers, M.I., Mueller, D.S., and Smith, D.L. Weather-based models for assessing the risk of Sclerotinia sclerotiorum apothecial presence in soybean (Glycine max) fields. Plant Disease. https://doi.org/10.1094/PDIS-04-17-0504-RE
Willbur, J.F.,Fall, M.L., Byrne, A.M., Chapman, S.A., McCaghey, M.M., Mueller, B.D., Schmidt, R., Chilvers, M.I., Mueller, D.S., Kabbage, M., Giesler, L.J., Conley, S.P., and Smith, D.L. Validating Sclerotinia sclerotiorumapothecial models to predict Sclerotinia stem rot in soybean (Glycine max) fields. Plant Disease. https://doi.org/10.1094/PDIS-02-18-0245-RE.
Fall, M., Willbur, J., Smith, D.L., Byrne, A., and Chilvers, M. 2018. Spatiotemporal distribution pattern of Sclerotinia sclerotiorum apothecia is modulated by canopy closure and soil temperature in an irrigated soybean field. Phytopathology. https://doi.org/10.1094/PDIS-11-17-1821-RE.
Willbur, J.F., Mitchell, P.D., Fall, M.L., Byrne, A.M., Chapman, S.A., Floyd, C.M., Bradley, C.A., Ames, K.A., Chilvers, M.I., Kleczewski, N.M., Malvick, D.K., Mueller, B.D., Mueller, D.S., Kabbage, M., Conley, S.P., and Smith, D.L. 2019. Meta-analytic and economic approaches for evaluation of pesticide impact on Sclerotinia stem rot control and soybean yield in the North Central U.S. Phytopathology. https://doi.org/10.1094/PHYTO-08-18-0289-R.
https://badgercropdoc.com/wp-content/uploads/sites/5/2022/07/IMG_3492-1-scaled.jpeg19202560damonsmithhttp://badgercropdoc.com/wp-content/uploads/sites/5/2018/05/bcd-color-300x153.pngdamonsmith2022-07-08 16:02:022022-07-08 16:03:05Hello White Mold, My Old Friend
Each year the Wisconsin Field Crops Pathology Program conducts a wide array of fungicide and disease management tests on alfalfa, corn, soybeans, and wheat. These tests help inform researchers, practitioners, and farmers about the efficacy of certain fungicide products on specific diseases and how to pair them with other disease management strategies. We hope you find this report useful in making decisions for the 2022 field season.
Mention of specific products in these publications are for your convenience and do not represent an endorsement or criticism. Remember that this is by no means a complete test of all products available. You are responsible for using pesticides according to the manufacturers current label. Some products listed in the reports referenced above may not actually have an approved Wisconsin pesticide label. Be sure to check with your local extension office or agricultural chemical supplier to be sure the product you would like to use has an approved label. Follow all label instructions when using any pesticide. Remember the label is the law!
https://badgercropdoc.com/wp-content/uploads/sites/5/2021/12/2021-Fungicide-Summary-Cover.png1206932damonsmithhttp://badgercropdoc.com/wp-content/uploads/sites/5/2018/05/bcd-color-300x153.pngdamonsmith2021-12-30 00:22:322021-12-30 00:22:462021 Wisconsin Fungicide Test and Disease Management Summary Now Available
After much deliberation, we made the difficult decision to pivot the 2021 Wisconsin Pest Management Update Meetings from a hybrid model to all virtual because of continued COVID-19 concerns and low registration numbers. Thus, the in-person events at Darlington (November 16, 2021), Chippewa Falls (November 17, 2021) and Kimberly (November 18, 2021) are now cancelled.
We will maintain the virtual offering on Friday November 19th(9:00 AM to Noon) and are adding a second virtual offering of the same program on Tuesday November 16th (1:00 PM to 4:00 PM) so participants can pick the option that best fits their schedule.
Mark Renz, Perennial Cropping Systems Extension Weed Specialist
Rodrigo Werle, Annual Cropping Systems Extension Weed Specialist
Nick Arneson, Extension Outreach Specialist, weeds
PJ Leisch Extension Entomology Diagnostician
Damon Smith, Extension Field Crops Pathologist
Topics will include updates in the area of weed, pest, and disease management along with a panel discussion and Q&A regarding the pest management challenges related to planting soybeans early.
Three (3) Pest Management CCA CEUs have been requested for this event.
Registration includes PDF of A3646 Pest Management In Wisconsin Fields.
We apologize for any inconvenience this decision may cause.
For 2021, the UW-Madison, Division of Extension and UW-Madison, Nutrient and Pest Management Program (NPM) will host the Pest Management Update Meetings as a hybrid event with (3) in-person meetings and (1) virtual option. All in-person meetings will be held from 1- 4pm local time at the venue listed for each location below. Check in will begin at 12:30pm with light refreshments available during the event.
This year’s speakers include: Mark Renz, Perennial Cropping Systems Extension Weed Specialist; Rodrigo Werle, Annual Cropping Systems Extension Weed Specialist; Nick Arneson, Weed Science Outreach Specialist; PJ Liesch Extension Entomology Diagnostician; and Damon Smith, Extension Field Crops Pathologist. Topics will include updates in the area of weed, insect and disease management. A panel discussion and Q&A regarding the pest management challenges related to planting soybeans early will follow.
The cost for the in-person events will be $50 per person and include a packet with materials including a hardcopy of A3646 Pest Management in Wisconsin Field Crops. This year ONLY, all in-person attendants will also receive a free copy of A Farmer’s Guide to Wheat Diseases, which is a $30 value. UW COVID safety protocols will be followed during the event.
The cost for the virtual event will be $20 per person with pre-registration required. The virtual registration will include links to PDFs of materials and a PDF version of the A3646 publication.
Below and in the attached flier are the dates, locations, and times for each event. Be sure to contact and register ONLY at the location you plan to attend. For the virtual option, links will be sent closer to the event.
SOUTHERN WI
Tuesday November 16
1pm-4pm
Ames Road Multi-Purpose Building 11974 Ames Rd, Darlington, WI 53530
https://badgercropdoc.com/wp-content/uploads/sites/5/2021/10/Screen-Shot-2021-10-11-at-12.50.15-PM.png15221176damonsmithhttp://badgercropdoc.com/wp-content/uploads/sites/5/2018/05/bcd-color-300x153.pngdamonsmith2021-10-11 19:39:392021-10-11 19:39:39Save the Dates and Attend the 2021 Pest Management Update Meetings
Damon Smith, Extension Field Crops Pathologist, Department of Plant Pathology, University of Wisconsin-Madison
Brian Mueller, Assistant Field Researcher, Department of Plant Pathology, University of Wisconsin-Madison
Camila Primieri Nicolli, Post-Doctoral Research Associate, Department of Plant Pathology, University of Wisconsin-Madison
It has been a while since I posted a corn and soybean disease update for Wisconsin in 2021, and that is because it has been reasonably quiet in the disease world up to this point. However, recent scouting and incoming reports indicate that this could change a bit as we move into August. Let’s take a look at what has happened so far this season and what to keep an eye out for over the next month or so.
The Soybean Situation
Figure 1. Phytophthora Root and stem rot of soybean
The Phytophthora Issue in Soybeans. During July we saw, and received reports, of some fields with Phytophthora root and stem rotof soybean (Fig. 1). I have received a lot of questions on why this happened. Are we seeing changes in the races of the Phytophthora organism in Wisconsin? My short answer is probably not. However, we have found a new species of Phytophthora in some fields that can affect soybean. The new species, Phytophthora sansomeana, can be found in mixed infections with P. sojae. Thus, even if we deployed the proper Rps resistances genes in our varieties, this “new” organisms might be causing some of the damage we observed this year.
What’s Up with White Mold? For most of the state of Wisconsin, we are through the critical bloom time for infection by the white moldfungus. It is now really too late to make a fungicide application that is economically viable. However, scouting fields through August can help you determine what worked, what didn’t, and to figure out your harvest order. Remember, a great way to move the white mold fungus around is by contaminated combines at harvest. Start harvesting fields with no or low white mold incidence and work your way to those fields that look worse. Also consider cleaning combines between fields to limit movement of the fungal survival structures (a.k.a apothecia – the things that look like rat turds!) from one field to the next.
Look out for SDS. Now is also a good time to be scouting for sudden death syndrome (SDS) in soybeans. I’m not sure we will have a bunch of SDS this year in Wisconsin, but we will see pockets for sure. Knowing where you see it and what you did in 2021 can help with making variety and seed treatment decisions for 2022 and beyond. Remember that we do have decent partial resistance to SDS in many commercial varieties. Start here and choose the most resistant variety that fits your environment. Then consider layering a seed treatment (either Saltro or ILeVO) for improved management of SDS. You can learn more about seed treatment performance by studying the Fungicide Efficacy for Control of Soybean Seedling Diseases chart. You can also learn more about the performance of ILeVO in multi-state research trials by reading this report.
The Corn Situation
Corn in Wisconsin has been reasonably free of disease up to this point this season. However, we have noted a few foliar diseases beginning to pop up. We have observed gray leaf spot (GLS)becoming easy to find in most fields, while northern corn leaf blight (NCLB) is starting to show up in a handful of fields we have visited. We are also paying close attention to the tar spot and southern rust situations, I’ll expand on these below.
How bad is tar spot? The Tarspotter app has been running at moderate to high risk of tar spot increase over the last couple of weeks in Wisconsin. Our scouting has confirmed that tar spot is present in at least 5 counties so far in Wisconsin (Fig. 2). All but Grant County show tar spot to be easy to find, but it is present in the lower canopy at low severity. In Grant County, we had to hunt a long time to find 2 spots in a research field on a known susceptible. These observations align with Tarspotter as it indicated just moderate risk in the southwest quadrant of Wisconsin, with high risk from south central to the north. If you plan on spraying a fungicide to manage tar spot, we recommend that this be done soon, prior to the R3/R4 growth stage. The goal here is to protect the leaves from the ear leaf up from continued increase by the fungus. If you would like to learn more about tar spot check out the new web book published by the Crop Protection Network.
Figure 2. County-level confirmations of tar spot in the U.S. as of August 2, 2021.
Continue to scout for tar spot and let us know what you are finding. We are now accepting good pictures of tar spot to confirm its presence in counties where we have observed it in years past, in Wisconsin. In counites that tar spot has never been confirmed, we would like to get a physical sample to verify (Fig 2). Feel free to reach out to me if you do find tar spot or any other disease of corn or soybean for that matter.
Figure 3. County-level confirmations of southern rust on corn in the U.S. as of August 2, 2021.
Has southern rust hit Wisconsin yet? The short answer is NO, not that we can find. We have scouted and asked several folks in our network, and nobody has observed and lab-confirmed southern rust in Wisconsin. However, figure 3 show county-level confirmations of southern rust of corn in the U.S. Based on this map, I would not be surprised if southern rust is confirmed in the next week or so in Wisconsin. Like tar spot, fungicides can be applied up to the R3/R4 growth stage with some benefits. Spraying after R4 will not yield economic returns. To learn more about managing southern rust of corn, check out the electronic fact sheet from the Crop Protection Network.
Keep an eye on the soybean and corn disease situation and scout, scout, scout. Let us know what you are finding!
https://badgercropdoc.com/wp-content/uploads/sites/5/2021/08/Soybean-Phytophthora-7.jpeg19202560damonsmithhttp://badgercropdoc.com/wp-content/uploads/sites/5/2018/05/bcd-color-300x153.pngdamonsmith2021-08-02 19:11:032021-08-02 19:11:03Wisconsin Soybean and Corn Disease Update – August 2, 2021
Damon Smith, Extension Field Crops Pathologist, Department of Plant Pathology, University of Wisconsin-Madison
Brian Mueller, Assistant Field Researcher, Department of Plant Pathology, University of Wisconsin-Madison
Roger Schmidt, Nutrient and Pest Management Program, University of Wisconsin-Madison
Soybean White Mold Update
Figure 1. White mold risk for Wisconsin on July 7, 2021 from the Sporecaster smartphone app.
Figure 1 illustrates the calculated risk of white mold for select Wisconsin locations for non-irrigated soybeans, as determined by Sporecaster for July 7, 2021. This means that if soybeans are flowering and the area between rows is filled in more than 50%, risk is just moderate in most locations of the state, with the exception of the far northeast portions of the state. This moderate risk indicates that there may not be apothecia present in fields in these locations at this time, however, the situation needs to be monitored closely as we move from R1 to the R2 growth stage. With a cooler, wetter weather pattern over the next 5-7 days, I believe that the risk for white mold will increase. I’m expecting a later onset (closer to the R3 growth stage) of white mold for much of the state in 2021. Warmer weather up to this point has pushed the risk of white mold potentially later in the bloom period.
Current White Mold Management Recommendation
I wrote extensively about white mold management in my previous post.Take some time to read the management recommendations there. I think folks should be patient yet monitor the situation carefully over the next several weeks. Again, if calculated risk continues to rise, then a fungicide application may be warranted as we progress through the bloom period. Be sure to download the Sporecaster app to get tailored recommendations for your fields. You can also adjust the action thresholds in the app (my map above is set at the default 40% threshold) and run specific models for irrigated environments.
Corn Tar Spot Update
Figure 2. Tar spot risk for Wisconsin on July 7, 2021 based on the Tarspotter smartphone app.
Figure 2 shows the calculated risk from Tarspotter (our smartphone prediction tool for tar spot) for July 7, 2021, for various locations in Wisconsin. The action threshold for high risk is 40% using the updated Tarspotter model for 2021. As you can see, the present risk is high for much of the state. Cooler, wet conditions over the next week will keep risk moderate to high. We have scouted several locations in Wisconsin and have been unable to find tar spot at this time in the state. However, figure 3 shows that tar spot has been found in some surrounding states, at low levels.
Current Tar Spot Management Recommendation
Monitoring Tarspotter (be sure to download it to your smartphone) and scouting should be done at this time to determine the diseases present. Tracking this situation, not only for tar spot but other corn diseases, will also help you make an in-season fungicide spray decision as we approach the very important VT/R1 growth stage. For more on making the decision to spray fungicide on corn, see my previous post. Get out and scout, scout, scout!
Figure 3. Confirmed tar spot cases in the U.S. as of July 7, 2021.
https://badgercropdoc.com/wp-content/uploads/sites/5/2019/08/IMG_4717.jpg9181632damonsmithhttp://badgercropdoc.com/wp-content/uploads/sites/5/2018/05/bcd-color-300x153.pngdamonsmith2021-07-07 16:00:282021-07-07 16:00:28Wisconsin Soybean and Corn Disease Update – July 7, 2021
Damon Smith, Extension Field Crops Pathologist, Department of Plant Pathology, University of Wisconsin-Madison
Shawn Conley, Extension Soybean and Small Grains Agronomist, Department of Agronomy, University of Wisconsin-Madison
Roger Schmidt, Nutrient and Pest Management Program, University of Wisconsin-Madison
Paul Mitchell, Extension Economist, Agricultural and Applied Economics, University of Wisconsin-Madison
Figure 1. Apothecia, a small mushroom-like structure of the white mold fungus that give rise to spores, which infect soybean flowers.
In Wisconsin, the first week of July brings us a heightened awareness of white mold in soybeans, and its management. The 2020 season in Wisconsin resulted in just pockets of white mold in the state. However, now is not the time to be complacent. If the weather becomes conducive in 2021, the situation could be much different than last year.
Remember that the white mold fungus infects soybeans through open and senescing flowers, by spores that are born from small mushroom-like structures called apothecia (Fig. 1). Remember that if the bloom period gets extended due to cool weather, this can lead to an extended window for infection by the fungus. Often cool weather is a double whammy as it is good for the white mold fungus and slows down soybean crop development, thereby extending bloom.
While conditions have been hot and dry in parts of the state, we are seeing cooler and wetter conditions over the last week. The white mold situation can change rapidly based on weather, thus anticipating favorable conditions for white mold, can help you protect your soybean crop.
Predicting White Mold
The flowering growth stages are a critical time to manage white mold in-season. You can view a fact sheet and new video on the subject. As you probably know, timing in-season fungicide sprays at the correct time during the soybean bloom period can be extremely difficult. To help solve this decision-making issue, models were developed at the University of Wisconsin-Madison in conjunction with Michigan State University and Iowa State University to identify at-risk regions which have been experiencing weather favorable for the development of white mold apothecia. These models predict when apothecia will be present in the field using combinations of 30-day averages of maximum temperature, relative humidity, and wind speed. Using virtually available weather data, predictions can be made in most soybean growing regions. To facilitate precise predictions and make the model user-friendly, we use Sporecaster smartphone application for Android and iPhone.
Figure 2. Sporecaster predictions for selected non-irrigated locations in Wisconsin for June 29, 2021
The purpose of the smartphone app is to assist farmers in making early season management decisions for white mold in soybean. The best time to spray fungicides for white mold is during flowering (R1 and R3 growth stages) when apothecia are present on the soil surface.
Sporecaster uses university research to turn a few simple taps on a smartphone screen into an instant forecast of the risk of apothecia being present in a soybean field, which helps growers predict the best timing for white mold treatment during the flowering period.
University research has indicated that the appearance of apothecia can be predicted using weather data and a threshold of percent soybean canopy row closure in a field. Based on these predictions and crop phenology, site-specific risk values are generated for three scenarios (non-irrigated soybeans, soybeans planted on 15″ row-spacing and irrigated, or soybeans planted on 30″ row-spacing and irrigated). Though not specifically tested we would expect row-spacings of 22 inches or less to have a similar probability response to fungicide as the 15 inch row-spacing.
The Sclerotinia apothecial models that underlie the Sporecaster prediction tool have undergone significant validation in both small test plots and in commercial production fields. In 2017, efficacy trials were conducted at agricultural research stations in Iowa, Michigan, and Wisconsin to identify fungicide application programs and thresholds for model implementation. Additionally, apothecial scouting and disease monitoring were conducted in a total of 60 commercial farmer fields in Michigan, Nebraska, and Wisconsin between 2016 and 2017 to evaluate model accuracy across the growing region. Across all irrigated and non-irrigated locations predictions during the soybean flowering period (R1 to early R4 growth stages) were found to explain end-of-season disease observations with an accuracy of 81.8% using the established probability thresholds now programmed in the app. We have made additional improvements for 2021, to further refine accuracy. So if you have used Sporecaster before, you might want to check the version in the “Help and Info” button to be sure you have version 1.4 of the Sporecaster. If you want to learn more about the science of Sporecaster, check out the embedded video below.
Not only can users run predictions of risk during the soybean bloom period for any field, you can also set up visual maps to look at multiple sites simultaneously. An example for the state of Wisconsin can be found in figure 2, which represents risk for June 29, 2021 for non-irrigated soybeans. Currently, if soybeans are flowering, risk is moderate to low in much of Wisconsin for non-irrigated soybeans, due to the recent hot and dry weather. In the north-eastern portions of the state, risk for flowering soybeans is higher due to more frequent rain events that have occurred there. Check back to this blog regularly as I will post maps like these with interpretation of risk for Wisconsin as we move through the season.
What to Spray for White Mold?
If you have decided to spray soybeans for white mold, what are the best products to use? Over the last several years we have run numerous fungicide efficacy trials in Wisconsin and in conjunction with researchers in other states. In Wisconsin, we have observed that Endura applied as a single application at 8 oz between the R1 and R2 growth stage performs well. We have also observed that the fungicide Aproach applied at 9 fl oz at R1 and again at R3 also performs comparably to the Endura treatment. Other fungicide options also include Omega and Proline. You can view results of past fungicide evaluations for Wisconsin by CLICKING HERE.If you would like to run tailored estimations of return on investment for various fungicide programs, you can use another smartphone application called Sporebuster.
What is Sporebuster?
When a fungicide application is needed to control white mold in soybeans, Sporebuster can help determine a profitable program. You enter your expected soybean price, expected yield, and treatment cost. Sporebuster instantly compares ten different treatment plans at once to determine average net gain and breakeven probability of each. You can mark, save and share by email, the best plans for your farming operation.
The purpose of Sporebuster is to assist soybean farmers in making a fungicide program decision that is profitable for their operation. Sporebuster is meant to complement Sporecaster. Once Sporecaster recommends a fungicide application, Sporebuster can be used to determine a profitable program.
Information that drives Sporebuster is based on research from 2009-2016 from across the upper Midwestern US. Statistical models were developed based on these data that included white mold pressure and yield response from fungicide for 10 common fungicide programs. Details about the research behind Sporebuster can be found by CLICKING HERE.
To watch an in-depth video on white mold management, CLICK HERE.
To find more information and download a fact sheet on white mold from the Crop Protection Network, CLICK HERE.
Scientific References
Willbur, J.F., Fall, M.L., Blackwell, T., Bloomingdale, C.A., Byrne, A.M., Chapman, S.A., Holtz, D., Isard, S.A., Magarey, R.D., McCaghey, M., Mueller, B.D., Russo, J.M., Schlegel, J., Young, M., Chilvers, M.I., Mueller, D.S., and Smith, D.L. Weather-based models for assessing the risk of Sclerotinia sclerotiorum apothecial presence in soybean (Glycine max) fields. Plant Disease. https://doi.org/10.1094/PDIS-04-17-0504-RE
Willbur, J.F.,Fall, M.L., Byrne, A.M., Chapman, S.A., McCaghey, M.M., Mueller, B.D., Schmidt, R., Chilvers, M.I., Mueller, D.S., Kabbage, M., Giesler, L.J., Conley, S.P., and Smith, D.L. Validating Sclerotinia sclerotiorumapothecial models to predict Sclerotinia stem rot in soybean (Glycine max) fields. Plant Disease. https://doi.org/10.1094/PDIS-02-18-0245-RE.
Fall, M., Willbur, J., Smith, D.L., Byrne, A., and Chilvers, M. 2018. Spatiotemporal distribution pattern of Sclerotinia sclerotiorum apothecia is modulated by canopy closure and soil temperature in an irrigated soybean field. Phytopathology. https://doi.org/10.1094/PDIS-11-17-1821-RE.
Willbur, J.F., Mitchell, P.D., Fall, M.L., Byrne, A.M., Chapman, S.A., Floyd, C.M., Bradley, C.A., Ames, K.A., Chilvers, M.I., Kleczewski, N.M., Malvick, D.K., Mueller, B.D., Mueller, D.S., Kabbage, M., Conley, S.P., and Smith, D.L. 2019. Meta-analytic and economic approaches for evaluation of pesticide impact on Sclerotinia stem rot control and soybean yield in the North Central U.S. Phytopathology. https://doi.org/10.1094/PHYTO-08-18-0289-R.
https://badgercropdoc.com/wp-content/uploads/sites/5/2018/08/IMG_37321-e1534709668147.jpg640480damonsmithhttp://badgercropdoc.com/wp-content/uploads/sites/5/2018/05/bcd-color-300x153.pngdamonsmith2021-06-29 19:10:312021-06-29 19:16:52Fireworks Fly! Time to Think about White Mold Management in Soybeans in Wisconsin
