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Mar 18, 2025
To your watch list for white mold, waterhemp, and nutrient deficiencies, add tar spot. Over the past few years tar spot, which resides in crop residue, has affected crops in Federated’s service areas.
“We go season by season to know how big a deal [tar spot] is,” said Sam Johnson, Federated ag sales rep from the Albertville location, but its potential to affect yields is real.
In a cool wet summer, the tar spot fungus will take off. A hot and dry start to the season won’t encourage the fungus as much. “We never know how big an issue it will be” until (or if) the right environmental conditions develop in any given season.
We know that tar spot survives in the residue, and it makes it through even the hardest Minnesota winters. Once it’s in a field, it stays. (It’s been in the Midwest for nearly 10 years.)
Tar spot first appears on the lower leaves of the corn plant and works its way up. It looks like actual specks of black tar on the leaves. However, these round/oblong spots won’t rub off. When corn stays wet for more than seven hours – from dew or precipitation – “that’s when tar spot really takes off,” said Johnson.
Federated recommends treating tar spot preventively with a fungicide such as Miravis® Neo. It is best applied at VT.
However, “fungicides are not only for tar spot,” said Johnson. “There’s a good chance you will get a yield bump off [a fungicide application], improving your yield,” in addition to combating other fungal diseases. Fungicides promote better plant health, and Miravis Neo provides broad spectrum control with residual lasting up to 45 days.
“VT applications of a preventive fungicide are definitely a solid agronomic choice,” added Kevin Carlson, Federated’s ag sales manager. As with many crop management choices, “sound agronomic recommendations drive economics – and better ROI,” he said.
Carlson highlighted this Winfield Answer Plot data that demonstrates significant yield response to fungicides.
While finalizing crop plans for 2025, contact your Federated Agronomist to discuss fungicides and potential treatment options for your fields.
“We go season by season to know how big a deal [tar spot] is,” said Sam Johnson, Federated ag sales rep from the Albertville location, but its potential to affect yields is real.
In a cool wet summer, the tar spot fungus will take off. A hot and dry start to the season won’t encourage the fungus as much. “We never know how big an issue it will be” until (or if) the right environmental conditions develop in any given season.
We know that tar spot survives in the residue, and it makes it through even the hardest Minnesota winters. Once it’s in a field, it stays. (It’s been in the Midwest for nearly 10 years.)
Tar spot first appears on the lower leaves of the corn plant and works its way up. It looks like actual specks of black tar on the leaves. However, these round/oblong spots won’t rub off. When corn stays wet for more than seven hours – from dew or precipitation – “that’s when tar spot really takes off,” said Johnson.
Federated recommends treating tar spot preventively with a fungicide such as Miravis® Neo. It is best applied at VT.
However, “fungicides are not only for tar spot,” said Johnson. “There’s a good chance you will get a yield bump off [a fungicide application], improving your yield,” in addition to combating other fungal diseases. Fungicides promote better plant health, and Miravis Neo provides broad spectrum control with residual lasting up to 45 days.
“VT applications of a preventive fungicide are definitely a solid agronomic choice,” added Kevin Carlson, Federated’s ag sales manager. As with many crop management choices, “sound agronomic recommendations drive economics – and better ROI,” he said.
Carlson highlighted this Winfield Answer Plot data that demonstrates significant yield response to fungicides.
While finalizing crop plans for 2025, contact your Federated Agronomist to discuss fungicides and potential treatment options for your fields.