What’s the Skinny on Foliar Fungicides for Alfalfa in Wisconsin?

Damon L. Smith, Extension Field Crops Pathologist, Department of Plant Pathology, University of Wisconsin-Madison

Figure 1. An alfalfa foliar fungicide trial in Arlington, WI.

With high commodity prices this spring and some freeze events affecting alfalfa in Wisconsin several weeks ago, I have been getting many questions about using fungicide on alfalfa. Should you do it? Is it economically viable? Does fungicide help to heal the freeze injury? The answers as you might expect are not always straight forward. Ain’t that just the way…..

What do we know about fungicides?

 Before I start into this topic, I’ll mention that you can find more extensive information about fungicides and how they work on the “Field Crops Fungicide Information” page. For all of the products labeled for alfalfa in Wisconsin, they should be applied when the stem have reached a length of 6-8 inches of growth. Applying at this time allows for preventative application (see below) and limits the amount of damage from wheel traffic. In addition, most of these products have at least a 14-day pre-harvest interval. To find information on the fungicides labeled for use in alfalfa in Wisconsin, download A3646-Pest Management in Wisconsin Field Crops.

 

Figure 2. Results of a large-plot foliar fungicide trial on 55V50 alfalfa at the Arlington Agricultural Research Station Located in Arlington, WI in 2016.

Remember that mode of action and mobility in the plant play a big role in how a certain fungicide should be used. As a rule of thumb remember that fungicides should mostly be used as protectants, applied prior to disease development to protect healthy plant tissue. Applying fungicide after extensive disease is observed almost never benefits the plant and is not economically viable. This means that you need to anticipate when disease might show up. In alfalfa, there are numerous foliar diseases that can affect the crop during the season, including common leaf spot, Letosphaerulina leaf spot, and Stemphylium leaf spot to name just a few. Most of these leaf spots are promoted by wet weather. Keeping good history of the diseases you have seen in the past on your farm, and tracking weather events (especially those where the weather is wetter than average) can help you anticipate the onset of these diseases. In alfalfa, we also must consider what our target cutting-duration is to be. We know from our more recent research (Figure 2) that cutting duration plays a significant role in the success of fungicide applications on alfalfa. If cutting duration is to be longer than 28-30 days, then the likelihood of an economic return is higher when fungicide is used. If the intent is to continue to cut using a shorter duration of 25-30 days, then the likelihood goes down in achieving an economic return when applying fungicide. Regardless of cutting duration, weather can also influence success. Abnormally wet weather can push pathogens faster. Dryer weather may mean that no fungicide is needed as the pathogen can’t increase as readily. So, pay attention to the rainfall as you make the decision to apply.

Why does cutting duration impact economic return when using fungicide on alfalfa?

Well, it simply comes down to the biology and epidemiology of the pathogens that affect the foliage of alfalfa. These pathogens don’t show up until about 14-21 days after cutting (or greenup). It takes them time to appear and start to get to a level that they cause the plant to defoliate. In the 1990s Duthie and Campbell reported that longer durations of cut between alfalfa crops allowed the pathogens to grow to levels that were more likely to be damaging. If we cut on shorter durations, we are physically removing the pathogen with the plant material during harvest, prior to when significant defoliation would happen. The application of fungicide in this scenario has little effect, because the pathogen was not causing any damage. Compare this to longer durations of cut, where the pathogens can rise to levels where they might cause defoliation. The application of fungicide in this scenario has a higher likelihood of success as it can slow the pathogen down and limit defoliation. Figure 2 shows data from 2016 in large alfalfa plots, where we gradually increased the duration of cut. Notice as the duration increased there was a corresponding increase in the return on investment (ROI) either as dry hay or in milk production.

Does fungicide help to heal freeze injury?

The short answer is no. Fungicides work to prevent and deter fungi. They work as primarily protectants on the plant and do not facilitate any healing of the plant. Can they protect an open injury from a pathogen? Perhaps, but data are weak at best, with this being a viable tactic. Thus, if you plan to use fungicide as a foliar application on alfalfa, make sure your target is indeed a foliar fungus.

Does alfalfa variety affect success when using a fungicide?

Directly, variety can play a small role in success with fungicides. Some varieties can be more susceptible to certain pathogens. However, the modern varieties I have looked at in recent years tend to respond similarly to these various foliar pathogens, with decent levels of partial resistance. We don’t see much separation in fungicide product on the various varieties.

The one caveat to consider though is if you are using reduced- or low-lignin varieties. If this is the case and your intent is to widen the cutting duration (longer than 30 days) then the likelihood of economic success when using a fungicide goes up. Note however, that this phenomenon is the same even if you are using a longer cutting duration on a conventional variety. Remember, cutting duration is really the important driver here.

Does fungicide product impact ROI on alfalfa?

Not really. You can find results from fungicide efficacy trials in Wisconsin on the “Wisconsin Fungicide Tests Summaries” page. Most of the fungicides labeled for alfalfa in Wisconsin have decent efficacy toward the major pathogen we run into. So, it simply comes down to that cutting duration again and what your best deal is on price for the fungicide of interest. Obviously, the lower that the fungicide cost is, the higher the ROI could be. But remember to get the timing of application correct and try to anticipate those potentially longer durations of cut.

Is the first crop the crop with the most potential for success when using foliar fungicide?

Perhaps. It makes the most sense. This crop has the highest yield potential and likely will sit out there the longest, exposed to pathogens and experiencing rain events. However, when we looked at this scientifically in some of our older work, the odds of success with a foliar fungicide are equal on all crops. What this means is that using foliar fungicide on any of the cuttings during the season could result in success. It simply comes down to that cutting duration and if the weather is wet enough to allow the pathogen to reach levels that cause defoliation on the plants, prior to harvest.

The Take-Home

In alfalfa, application of fungicide should be reserved when the risk of foliar disease is high. Wet weather leading to increased durations between cuttings can lead to higher risk of disease and warrant application of fungicides. Dry weather or short durations between cutting intervals lead to low risk of foliar disease development. Fungicides are not warranted under these conditions and quality is not readily affected by fungicide applications under short cutting durations.  

2020 Wisconsin Field Crops Pathology Fungicide Tests Summary Now Available

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

Each year the Wisconsin Field Crops Pathology Program conducts a wide array of fungicide 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. This year we were a bit delayed in publishing the report, due to the challenges of COVID-19. However, we do appreciate your patience and hope you find the report useful in making decisions for the 2021 field season.

The 2020 Wisconsin Field Crops Fungicide Test Summary is available by clicking here. These tests are by no means an exhaustive evaluation of all products available, but can be used to understand the general performance of a particular fungicide in a particular environment. Keep in mind that the best data to make an informed decision, come from multiple years and environments. To find fungicide performance data from Wisconsin in other years, visit the Wisconsin Fungicide Test Summaries page. You can also consult publication A3646 – Pest Management in Wisconsin Field Crops to find information on products labeled for specific crops and efficacy ratings for particular products. Additional efficacy ratings for some fungicide products for corn foliar fungicidessoybean foliar and seed-applied fungicides, and wheat foliar fungicides can be found on the Crop Protection Network website.

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!

2019 Wisconsin Field Crops Pathology Fungicide Tests Summary Now Available

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

Each year the Wisconsin Field Crops Pathology Program conducts a wide array of fungicide 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. The 2019 Wisconsin Field Crops Fungicide Test Summary is now available. These tests are by no means an exhaustive evaluation of all products available, but can be used to understand the general performance of a particular fungicide in a particular environment. Keep in mind that the best data to make an informed decision, come from multiple years and environments. To find fungicide performance data from Wisconsin in other years, visit the Wisconsin Fungicide Test Summaries page. You can also consult publication A3646 – Pest Management in Wisconsin Field Crops to find information on products labeled for specific crops and efficacy ratings for particular products. Additional efficacy ratings for some fungicide products for corn foliar fungicidessoybean foliar and seed-applied fungicides, and wheat foliar fungicides can be found on the Crop Protection Network website.

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!

2018 Wisconsin Field Crops Pathology Fungicide Tests Summary Now Available

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

Each year the Wisconsin Field Crops Pathology Program conducts a wide array of fungicide 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. The 2018 Wisconsin Field Crops Fungicide Test Summary is now available. These tests are by no means an exhaustive evaluation of all products available, but can be used to understand the general performance of a particular fungicide in a particular environment. Keep in mind that the best data to make an informed decision, come from multiple years and environments. To find fungicide performance data from Wisconsin in other years, visit the Wisconsin Fungicide Test Summaries page. You can also consult publication A3646 – Pest Management in Wisconsin Field Crops to find information on products labeled for specific crops and efficacy ratings for particular products. Additional efficacy ratings for some fungicide products for corn foliar fungicides, soybean foliar and seed-applied fungicides, and wheat foliar fungicides can be found on the Crop Protection Network website.

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!

2018 Pest Management Update Meeting Series Announced

The schedule for the Wisconsin Pest Management Update meeting series has been set. Presentations will include agronomic pest management information for Wisconsin field and forage crops. Speakers include Mark Renz and Rodrigo Werle, weed scientists, Damon Smith, plant pathologist, and Bryan Jensen, entomologist.

The format will be the same as in 2017. Meetings will either be in the morning or afternoon On November 12-16, 2018. Simply choose a day/location to attend with each meeting running 3 hours. Note that several locations and contacts have changed since 2017 (marked with * in the meeting flier). Please read the informational flier carefully and make sure you contact the appropriate person at your desired location.

2018 Pest Management Update Highlights:

  • Integrated Pest Management Updates in corn, soybeans, alfalfa, and small grains: Update on new products and/or use of existing products as well as brief highlights of the 2018 pest situations in each crop.
  • Waterhemp management
  • Dicamba off-target research
  • Pollinator Training
  • Soybean cyst nematode training and management

Please make your reservation with the host contact at least one week prior to the scheduled meeting date.

Three hours of Certified Crop Advisor CEU credits in pest management are requested for each session.

To download a PDF of the flier, CLICK HERE.

Welcome to badgercropdoc.com: A New Web Resource for Wisconsin Field Crops Pathology Research and Outreach

Damon Smith, Extension Field Crops Pathologist, Department of Plant Pathology, University of Wisconsin-Madison

Welcome to badgercropdoc.com! Badger Crop Doc is a one-stop-shop for all things Wisconsin Field Crops Pathology related. We have merged the website and blog found at / with our University of Wisconsin academic website, so that all information can now be found in one place. If you subscribed to the blog posts at /, don’t worry, we have already moved your e-mail over to badgercropdoc.com. Be sure that browsers are now pointed to the new URL and check your e-mail folders to be sure blog postings aren’t going to junk or trash. No new postings will be added to /.

BadgerCropDoc was made possible with support from the Wisconsin Soybean Marketing board and is meant to be complementary to badegrbean.com and coolbean.info, while offering research-based information for the major field crops of Wisconsin. We hope you enjoy this new resource. As always, please let us know what you think. We would love to hear feedback.

2017 UW Extension Pest Management Update Meeting Series

Be sure to get the latest field crop pest management updates, by attending the 2017 PMU Meetings!

Damon L. Smith, Extension Field Crops Pathologist, University of Wisconsin-Madison

Mark your calendars as the UW Extension’s Pest Management Update meetings are just around the corner (November 6-10). This year’s program will follow the same format as in 2016. Meetings will either be in the morning or afternoon and will run for 3 hours. Morning meetings will begin promptly at 9am and run to 12pm. Afternoon meetings will begin at 1pm and conclude at 4pm.

The full schedule with dates, meeting locations, and registration contact information are in the link below. Please register with the host agent at least 1 week prior to the meeting at the location you wish to attend.

Please attend the meeting location at which you registered. Each meeting in the series is a separate county-based event and host agents cannot interchange registrant fees or meal counts.

Three hours of Certified Crop Advisor CEU credits in pest management are requested for each session.

The speakers will be extension specialists Mark Renz, weed scientist, perennial cropping systems; Dan Heider, IPM outreach specialist, Bryan Jensen, entomologist, and Damon Smith, field crop pathologist.

2017 Pest Management Update Topics:

  • Integrated Pest Management Updates in corn, soybeans, alfalfa, and small grains: Update on new products and/or use of existing products as well as brief highlights of the 2017 pest situations in each crop.
  • Wisconsin herbicide resistance update by Mark Renz
  • In-depth weed diagnostic and management training by Mark Renz and Dan Heider

CHECK OUT THE FULL MEETING SCHEDULE BY CLICKING HERE!

2016 Wisconsin Field Crops Pathology Fungicide Tests Summary Now Available

Damon L. Smith, Extension Field Crops Pathologist, University of Wisconsin-Madison

The 2016 Wisconsin Field Crops Pathology Fungicide Tests Summary is now available online as a downloadable PDF. This report is a concise summary of pesticide related research trials conducted in 2016 under the direction of the Wisconsin Field Crops Pathology program in the Department of Plant Pathology at the University of Wisconsin-Madison.  We thank many summer hourlies and research interns for assisting in conducting these trials.  We would also like to thank Carol Groves, Jaime Willbur, Megan McCaghey, Bryan Jensen, John Gaska, Adam Roth and Shawn Conley for technical support.

Mention of specific products in this publication are for your convenience and do represent an endorsement or criticism.  This by no means is a complete test of all products available.  You are responsible for using pesticides according to the manufacturers current label.  Follow all label instructions when using any pesticide.  Remember the label is the law!

To download the current report, or past reports visit the SUMMARIES page by clicking here.

What about Fungicide on Alfalfa for Dairy Production in Wisconsin?

Fungicide on Alfalfa

Damon L. Smith, Extension Field Crops Pathologist, University of Wisconsin-Madison

Thinking about fungicide for your alfalfa crop in Wisconsin? Typically in a 30-day cutting interval on alfalfa, like that used in dairy production in Wisconsin, foliar diseases cause minimal damage. Coupled with the heightened risk of fungicide resistance development toward these modern fungicides, application of fungicide on alfalfa for dairy production is not recommended unless heavy disease pressure is observed. CHECK OUT THIS VIDEO TO LEARN MORE! You can also CLICK HERE to download an informational fact sheet on the return on investment potential when using fungicide on alfalfa in Wisconsin.

2015 UW Extension Pest Management Update Meeting Series

General Agronomy

Be sure to get the latest field crop pest management updates, by attending the 2015 PMU Meetings!

Damon Smith, Extension Plant Pathology Specialist

Mark your calendars as the UW Extension’s Pest Management Update meetings are just around the corner (November 9-19). This year’s program will follow the new format established in the 2014 series, with more interaction between presenters and the audience, and participation by Bryan Jensen and Dan Heider with the University of Wisconsin Integrated Pest and Crop Management Program.

We will focus the entire morning (10-noon) on integrated pest management updates by crop (corn, soybean, alfalfa, and small grains). This session will be streamlined to focus on new pesticide registrations, pest updates, and highlight important issues from 2015. After lunch, topics will be more focused on specific updates and diagnostic training. These topics will include:

  • Herbicide resistance update and identification
  • Managing corn rootworms
  • Soybean stem disease identification

These diagnostic and focused trainings were a big hit in 2014 so don’t miss out in 2015!

The full schedule with dates, meeting locations, topics and registration contact information are in the link below. Please register with the host agent at least 1 week prior to the meeting at the location you wish to attend.

Note that due to low turnout in past years, the Arlington location has been dropped from the rotation in 2015. There will only be 7 locations to attend the update meetings, rather than 8 locations as in previous years. Be sure to look at the 2015 schedule included with this article when selecting your preferred date and location.

Please attend the meeting location at which you registered. Each meeting in the series is a separate county-based event and host agents cannot interchange registrant fees or meal counts.

Four hours of CCA CEU pest management credits are requested and available at each location.

The speakers will be extension specialists Mark Renz, weed scientist, perennial cropping systems; Dan Heider, IPM outreach specialist, Bryan Jensen, entomologist, and Damon Smith, field crop plant pathologist.

2015 Pest Management Update Topics:

  • Integrated Pest Management Updates in corn, soybeans, alfalfa, and small grains: Update on new products and/or use of existing products as well as brief highlights of the 2015 pest situations in each crop.
  • Herbicide resistance update and identification: Dan Heider and Mark Renz discuss the herbicide resistant weed situation in Wisconsin and how to identify problematic situations.
  • Managing corn rootworms: Bryan Jensen will take you through identifying corn rootworm problems and how to manage them in field corn.
  • Soybean stem disease identification: Damon Smith will discuss the 2015 soybean stem disease situation in Wisconsin. He will offer tips on how to identify and manage the various stem diseases that cause problems in Wisconsin.

Check out the full meeting schedule at this link.