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
Damon Smith, Extension Field Crops Pathologist, Department of Plant Pathology, University of Wisconsin-Madison
Brian Mueller, Researcher II, Department of Plant Pathology, University of Wisconsin-Madison
Roger Schmidt, Nutrient and Pest Management Program, University of Wisconsin-Madison
It didn’t take long this year to find tar spot in the corn crop in the Midwest. Last week brought on the first county-wide reports of tar spot in Iowa and now we have found tar spot on corn in Columbia Co. Wisconsin as of July 6, 2022 (Fig 1). This is the earliest in the season, and the earliest growth stage of corn, that I have ever seen tar spot in Wisconsin. With that said, the severity is extremely low and does not necessitate spraying fungicide at the moment! So what should you do now?
Figure 1. Map of U.S. counties where tar spot has been confirmed in the 2022 season, as of July 7, 2022. Map source: https://corn.ipmpipe.org/tarspot/.
What should I do?
My advice is to get prepared and make sure you have the tools in place to deal with this problem. As I said last season, tar spot is here to stay and we need to simply be prepared and ready to fight the disease. The first line of defense is to know if you have had tar spot before. This will tell you if there is resident inoculum sources present that can initiate epidemics. If you have seen tar spot on your farm before, then assume the pathogen is present and in close proximity to corn (the host). Remember the disease triangle? The last component of the triangle is the weather. If there has been conducive weather then the triangle has been met and risk is high for finding tar spots. So how do you know if the weather is conducive? Well, there is an app for that!
Tarspotter and Field Prophet are both Smartphone applications that can help you determine if the weather has been conducive to put your corn crop at high risk of tar spot development. Figure 2 shows a map of Wisconsin from the Field Prophet version of the tool that is showing that weather has been highly conducive for the development of tar spots. The app DOES NOT tell you if the pathogen is present. We are working on this part of the triangle to improve our predictions, but you need to determine if the pathogen is present in your field. This tool just tells you if the weather has been conducive.
Figure 2. A Screen shot of a map developed in the Field Prophet app showing risk for tar spot development in Wisconsin as of July 7, 2022.
So what weather is conducive for tar spot development? Well, it is different that the weather needed to grow corn. Yes, precipitation is helpful, but more importantly, we need leaf wetness. Specifically leaf wetness at night. What gives leaf wetness this time of year other than rain? That would be high dew points and humidity. These variables are included in the models that run in Tarspotter and Field Prophet. We also include temperature (not as important as you think it would be) and precipitation. These variables are measured over the last 14 days and included in each daily run of the tool. We use the GPS on the smartphone to pull down cloud-based weather for a precise location. Thus, these results are site-specific. I also like to the use the Field Prophet version of the models as this version provides a 7-day trend line on how weather has been progressing and also allows for a true 7-day forecast. These additional tools can better help with the decision-making process.
My corn is at V8 or V10, should I spray Fungicide?
My short answer is no! The disease is just getting started. It is at low severity (Fig. 3) and is low in the canopy on leaves that are not going to contribute to yield. My advice is to use your prior knowledge of where tar spot occurred and the Tarspotter tool to help guide your scouting efforts. Get out into the fields and know what you are dealing with. Target field planted to known susceptible hybrids. Get yourself prepared and use those lower leaves to monitor severity and tar spot progress. Be ready to protect (put fungicide on) those leaves that contribute to yield (ear leaf and above), later on.
When should I spray fungicide? What should I use?
Figure 3. A single tar spot on a lower leaf of corn in Wisconsin on July 6, 2022.
Our recent work has shown that if you get the product right, you can generally control tar spot to the point to preserve your yield potential, with one well timed spray. So what is that timing of the single application? That would be between the VT (tasseling) and R3 (milk) growth stages. We determined this using a series of trials where we did single applications of fungicide for individual growth stages. Figure 4 shows the results of two trials from 2020 where the window of opportunity to reduce the severity of tar spot with a single application is between VT and R3. Yes, the two-spray program (V8+VT) did also control tar spot, but all the work was done by the VT application, not the V8-timed spray! Thus, if you chose to spray your 2022 crop at this point in the season, you stand a good chance of having to come back with a second application later in the season.
Also notice in figure 4 that Tarspotter was tested in 2020 and did not perform very well. This was an early iteration of the tool and we have since improved its performance. So please don’t judge the tool based on this figure. If you would like to see how Tarspotter performed in advising fungicide applications last season, check out this article based on the 2021 field season.
Figure 4. Tar spot intensity after spraying fungicide once at each corn growth stage during the 2020 field season.
Figures 5 shows the tar spot severity, while figure 6 the corn yield, from those trials where a single application of each of the products was made at the VT growth stage. Clearly you have lots of options when it comes to products that can control tar spot. That is good news! Yes, some products do a bit better in preserving yield over others, but all fungicides tested in 2021 resulted in numerically higher yields than not-treating. Remember that 2021 was a banner year for tar spot. These results might not be as clear in a year where tar spot is not as intense.
Figure 5. Tar spot severity from multi-state trials where corn was treated with foliar fungicides at the VT corn growth stage, or not treated. Source: Telenko et al., 2022 – https://apsjournals.apsnet.org/doi/10.1094/PHP-02-22-0012-BR.
Figure 6. Corn yield from multi-state trials where corn was treated with foliar fungicides at the VT corn growth stage, or not treated. Source: Telenko et al., 2022 – https://apsjournals.apsnet.org/doi/10.1094/PHP-02-22-0012-BR.
The Conclusion
DON’T PANIC! This is just a call to be ready. Download the apps and know what the weather is doing. Use your prior knowledge and scouting in key locations to track tar spot. Get your management plan in place. Have your fungicide of choice available. Communicate with your custom applicator. Be ready to spray between the VT and R3 growth stages if you plan to use just one fungicide application and you are seeing tar spot increase. If you spray between the V8 and VT growth stages, be ready to monitor the smartphone apps and do more scouting as you might have to pull the trigger again later in the season. Get out and SCOUT, SCOUT, SCOUT!
https://badgercropdoc.com/wp-content/uploads/sites/5/2022/07/IMG_7685-scaled.jpg25601920damonsmithhttp://badgercropdoc.com/wp-content/uploads/sites/5/2018/05/bcd-color-300x153.pngdamonsmith2022-07-07 17:46:552022-07-07 17:55:04We Found Tar Spot of Corn in 2022, Now What?
Damon L. Smith, Extension Field Crops Pathologist, Department of Plant Pathology, University of Wisconsin-Madison
In Wisconsin, wheat diseases have been nearly non-existent up to this point. Cool weather has generally kept wheat disease at low levels. However, increase frequency of rain events and moderate temperatures over the next 7-10 days will likely increase disease risk, especially Fusarium head blight (FHB or Scab).
Fusarium head blight risk for susceptible winter wheat varieties for June 1, 2022.
We are entering the window for fungicide applications for FHB here in Wisconsin. Currently the Fusarium Head Blight Risk toolis predicting more areas of moderate to high risk in Wisconsin for FHB than it did a week ago (Fig. 1). If highly susceptible wheat varieties were planted in Wisconsin, the current risk is high across most of the state. Rainy conditions in the next seven days will likely push this risk higher. Now is the time to consider a fungicide application to manage FHB in Winter wheat in the state.
In winter wheat in Wisconsin, research has demonstrated that the best time to apply fungicides is between the start of anthesis (first anthers out) to 7 days after the start of anthesis. This same research has demonstrated that waiting to apply fungicides 5 days after the start of anthesis, optimizes deoxynivalenol (DON or vomitoxin) reductions in finished wheat. This is due to the fact that head emergence in Wisconsin can be very uneven. Waiting 5 days after the start of anthesis may help with optimizing application timing to maximize heads flowering and receiving fungicide protection. Fungicide choice is also critical, with Prosaro, Caramba, and Miravis Ace providing the most consistent control of Fusarium head blight and reduction of DON in trials in Wisconsin. Fungicides containing strobilurin fungicides should be avoided after the boot stage of wheat as these products can increase DON levels in finished grain. Fungicide efficacy information from Wisconsin can be found at https://badgercropdoc.com/research-summaries/. National ratings for fungicide efficacy of small grains can be found HERE. Additional thoughts on using fungicide on wheat can be found in this Bumper Crops Video.
We also know that in Wisconsin, that a fungicide application targeted to manage FHB will pay for itself almost every time. You can find published research information on the probability of a return on fungicide investment by clicking HERE. Be sure to focus on comparing the “current” level of treatment to the “mid-level” of treatment in the publication. The only difference between these two treatment plans was the application of fungicide at Feekes 10.5.1 to manage FHB. The “mid-level” plan returned on average more than $120 per acre above the “current” management plan in our trials.
Damon L. Smith, Extension Field Crops Pathologist, Department of Plant Pathology, University of Wisconsin-Madison
Figure 1. Fusarium Head Blight Risk Map – May 24, 2022.
Winter Wheat is Wisconsin is in the “boot “or heading in the southern part of the state. Currently the Fusarium Risk Assessment Map is showing low risk for Fusarium head blight development (Fig 1). Rain is forecast for the next several days, thus, the risk is likely to climb as we approach wheat heading and flowering. Wheat farmers and consultants should pay attention to weather closely over the next several weeks as the decision to apply fungicide will need to be made during this time.
In winter wheat in Wisconsin, research has demonstrated that the best time to apply fungicides is between the start of anthesis (first anthers out) to 7 days after the start of anthesis. This same research has demonstrated that waiting to apply fungicides 5 days after the start of anthesis, optimizes deoxynivalenol (DON or vomitoxin) reductions in finished wheat. This is likely since head emergence in Wisconsin can be very uneven. Waiting 5 days after the start of anthesis may help with optimizing application timing to maximize heads flowering and receiving fungicide protection. Fungicide choice is also critical, with Prosaro, Caramba, and Miravis Ace providing the most consistent control of Fusarium head blight and reduction of DON in trials in Wisconsin. Fungicides containing strobilurin fungicides should be avoided after the boot stage of wheat as these products can increase DON levels in finished grain. Fungicide efficacy information from Wisconsin can be found at https://badgercropdoc.com/research-summaries/. National ratings for fungicide efficacy of small grains can be found HERE. Additional thoughts on using fungicide on wheat can be found in this Bumper Crops Video.
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
Richard W. Webster, University of Wisconsin-Madison; Maxwell O. Chibuogwu, University of Wisconsin-Madison; Hannah Reed,University of Wisconsin-Madison; Brian Mueller,University of Wisconsin-Madison; Carol L. Groves, University of Wisconsin-Madison; Albert U. Tenuta, Ontario Ministry of Agriculture, Food and Rural Affairs; Martin I. Chilvers, Michigan State University; Kiersten A. Wise, University of Kentucky; and Damon Smith, University of Wisconsin-Madison.
A new research update has just been published on the Crop Protection Network summarizing recent work conducted to understand how deoxynivalonol (DON or vomitoxin) accumulates in silage corn plants. We also took a look at managing this issue with fungicides. The summary of the work is below, or you can click here to read the entire research update.
Gibberella ear rot
Summary
Fusarium graminearum is a fungus that causes the two diseases, Gibberella ear rot and Gibberella stalk rot, which can lower yield and feed quality of silage corn.
This fungus produces a secondary metabolite called deoxynivalenol (DON; also known as vomitoxin) during development and colonization of the corn plant, which is toxic to both humans and livestock.
Our research found that infection, colonization, and production of DON by F. graminearum in ears and stalks of corn plants can differ, and suggests that the two diseases can occur independently of each other.
Foliar fungicides reduced foliar diseases in both years, but the effects of fungicide on DON concentrations across entire plants were inconsistent in 2019.
Scouting for Gibberella ear and stalk rot and testing for DON in silage corn is important even if visual ear symptoms are not present as DON may still be accumulating in the stalks.
https://badgercropdoc.com/wp-content/uploads/sites/5/2018/09/IMG_3864-e1537388418650.jpg640480damonsmithhttp://badgercropdoc.com/wp-content/uploads/sites/5/2018/05/bcd-color-300x153.pngdamonsmith2021-11-30 17:45:592021-11-30 17:46:45New Research Update: Disease Development and Deoxynivalenol Accumulation in Silage Corn
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
Roger Schmidt, Nutrient and Pest Management Program, University of Wisconsin-Madison
…let’s start working on how to manage it in Wisconsin (Some thoughts on how to do this in the “Other Resources” below). While we haven’t had major epidemics every year since 2016, tar spot has been found each year and caused problems in some corn fields since its discovery. Figure 1 show counties in the U.S. that tar spot has been found, to date. I’m sure there are others in Wisconsin, feel free to send me pictures or samples for confirmation.
Yes, 2018, and now 2021, have clearly seen significant tar spot epidemics that affect yield. What challenges will we be dealing with as we move into harvest in 2021? Here are my thoughts.
Silage Corn Harvest
I took a crack at this one in the video below.
Many are already chopping or have finished at this point. However, it is important to realize that tar spot can dry corn plants abnormally fast. Thus, packing the bunker and initiating fermentation can be a challenge. This can lead to secondary issues such as fungal growth in the bunker and/or increases in mycotoxins. Monitor things carefully and do the best job you can this year putting the crop in the bunker. This year isn’t the year to cut corners!
Grain Corn Harvest
Now is the time to get out there and see how much tar spot is in your grain corn crop and start making plans for order of harvest. If the crop is shutting down abnormally fast, then stalk integrity is going to start to become an issue. Prioritizing fields with high tar spot pressure for harvest first, will help to limit lodging issues and ease harvest headaches. Also, be sure to check for other issues as you scout, like ear rots, that can lead to mycotoxin issues. Get mycotoxin tests if you think you might have problems, before you put it in the bin. You don’t want to mix grain that is low in mycotoxins with grain that has high levels of mycotoxins. Incidentally, no mycotoxins have been implicated directly with tar spot.
More on the grain harvest situation can viewed in the video below.
Tar Spot Management Nuggets as Harvest Begins
The two big questions I have been getting lately about tar spot management are: 1) How is tar spot hybrid resistance looking? 2) How does fungicide work on tar spot?
First, hybrids…There aren’t any hybrids that we know of that are completely resistant. Yes, some are more partially resistant that others. Now is also a good time to look at hybrids. Those that show less disease and are still green are going to be better candidates to grow next year versus those that are showing lots of tar spot and have already dried down. Look at local hybrid trials, especially. Write down the numbers of hybrids that look good. Leave the others that look bad.
Now the fungicide question. Yes, there are some fungicides that work. Yes, even on susceptible hybrids they can help. However, like white mold in soybeans, fungicide efficacy is largely dependent on fungicide application timing. Miss the onset of the epidemics, or periods where the epidemic is rapidly increasing, and even a great fungicide will look terrible.
To help with the timing decision we have developed the Tarspotter smartphone app. We have been testing this app over the last couple of seasons. It is useful in that it can help you anticipate epidemics of tar spot to get fungicide applications on preventatively, when they will work the best. Figure 2 below shows the performance of a fungicide application applied using Tarspotter versus a single application at the VT growth stage versus the non-treated check. While the standard VT application did well, two-applications (one at the start of the epidemic at V10 and another at R2) were needed to hold tar spot off in 2021. As you can clearly see, Tarspotter can be used to make these complicated spray decisions and optimize fungicide performance.
Figure 2. Non-treated check on the left, fungicide applied at VT only in the center, and fungicide applied at V10 and R2 according to Tarspotter on the right.
As for fungicide products, we continue to see mixed-mode-of-action products work more consistently that single-mode-of-action products. This fall we should have some updated fungicide performance information that might shed more light on this subject. Stay tuned!
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.pngdamonsmith2021-09-10 15:40:162021-09-11 13:28:07Tar Spot Is Here To Stay…
