Read answers to your top agronomic questions. Download the 2023 Product Agronomy Research (PAR) Report HERE.

Back to Articles

Identifying and Treating Tar Spot

BY Dairyland Seed Agronomy Team
2023 Corn In Season Disease Management

 

The Dairyland Seed footprint has seen varying levels of tar spot infection ranging from none to areas that have seen infection for the past three or four weeks. The map below shows confirmed cases of tar spot. If you would like a more in-depth look, refer to our August 2 article found here:  https://www.dairylandseed.com/articles/tar-spot-update/

 

Confirmed Cases: Map as of 8/14/2023 Updated map can be found at https://corn.ipmpipe.org/tarspot/

 

 

Identification
  • Small, black, circular, raised lesions (stromata) appear on leaves, husks, and tassels.
  • Stromata cannot be removed from leaf tissue with water or rubbing.
    • Commonly misdiagnosed with frass (insect poop), rotten or aged pollen, and rust pustules. These can be removed by rubbing the leaf or scraping it with your fingernail.

 

 

 

Disease Triangle

 

Treatment
  • Research shows the most advantageous timing of fungicide application to be VT to R2 (tassel to brown silk blister).
  • Fungicides containing both a Group 3 (DMI Triazole) and Group 11 (Strobilurin) modes of action are the most effective with tar spot. You can find specific product efficacy can be found at the Crop Protection Network website.
  • Fungicide treatments after the R2 to R3 timing have not shown to increase yields when applying for tar spot control. Therefore, R3 (milk stage) is the cut-off for applications of fungicide made for tar spot control in corn grown for grain.
  • Fungicide applications in corn grown for silage should take into consideration the preharvest interval of the fungicide being applied. The preharvest interval (PHI) is the amount of time that must pass between application and harvest of the crop. Most fungicides have a 14-to-21-day PHI.

 

Brian Weller
Brian Weller
Western Region
507.456.3034
Rod Moran
Rod Moran
Western Region
507.456.3034
Dan Ritter
Dan Ritter
Central Region
219.863.0583
Branden Furseth
Branden Furseth
Northern Region
608.513.4265
Mark Gibson
Mark Gibson
Eastern Region
260.330.8968
Amanda Goffnett
Amanda Goffnett
Eastern Region
989.400.3793
Ryan Mueller
Ryan Mueller
Eastern Region
989.400.3793
Enjoying our Agronomy Updates? Suggestions for topics you'd like us to weigh in on? Drop us an email at dairylandseed@dairylandseed.com. We'd love to hear from you!
Previous Post Back to All Posts Next Post
Subscribe for more insights delivered straight to your inbox.
You may also like...
  • Deciding or Choosing a Nitrogen Rate
    As we are in or just getting done with many hunting seasons, asking an Agronomist to pick a Nitrogen (N) rate for your corn crop is akin to a asking a hunter what his or her favorite weapon to hunt with is. The answer in both instances is probably “well it depends.” As an Agronomist, before recommending a nitrogen rate, I typically ask several questions. It’s often said that the number of questions I might ask is comparable to the number of inquiries new parents make when consulting a physician about their child. Before suggesting an N rate, I have considered the following background information and questions:
    Read more
  • 2024 Silage Performance Summary Now Available
    As the seed industry continues to evolve, there seems to be less emphasis on researching and providing corn hybrids that perform well for silage. For Dairyland Seed, however, silage continues to be very important for our customers, thus it is a major part of our corn portfolio.
    Read more
  • Staying Safe with Life-Critical Rules
    Farmers from North Dakota to Indiana are anxious to start the season’s harvest as the days shorten and the crops dry down. But before you head to the fields, take a moment to review important safety procedures.
    Read more
Find Your Rep