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Tar spot confirmed in 4 northeastern Kansas countiesTar spot confirmed in 4 northeastern Kansas counties

K-State confirms tar spot has been found in corn in Doniphan, Atchison, Jefferson and Brown counties.

Jennifer M. Latzke

July 11, 2023

2 Min Read
Corn tar spot fungus on cornstalk leaf
TAR SPOT DISCOVERED: Kansas State University has confirmed reports of tar spot found in corn in Doniphan, Atchison, Jefferson and Brown counties in northeast Kansas. Experts offer advice for scouting and treatment. JJ Gouin/Getty Images

Kansas State University row crop plant pathologist Rodrigo Onofre reported in the July 6 Agronomy eUpdate that tar spot has been confirmed in four northeast Kansas counties: Doniphan, Atchison, Jefferson and Brown.

Tar spot is a disease in corn caused by the fungus Phyllachora maydis. The tar spot spores can overwinter on infested corn residue on the soil surface until the next growing season. Then, wind and rain splash can spread the spores to nearby fields.

Onofre writes that recent rains likely promoted tar spot development in these confirmed fields. Irrigated corn can be at higher risk for yield or silage loss from tar spot. Rainfall and high humidity conditions are ideal for tar spot to take hold and spread.

Tar spot develops as small, black, raised spots that can appear on one or both sides of the corn leaves, leaf sheaths and husks. They can be found on healthy green tissue as well as on dying brown tissue. Scouts might confuse tar spot with insect poop, which can also appear as black spots on the surface of the leaf.

Fungicides can be effective to control tar spot, and the best timing is to apply on corn when fungal diseases are active in the corn canopy. Onofre recommends also applying when the corn is at least nearing VT/R1 (tassel/silk) or R2 (blister) stages. The National Corn Disease Working Group has a list of effective fungicides labeled for tar spot at bit.ly/cornfungicide.

Onofre warns that higher disease pressure may call for a second application. And remember, there are no benefits from fungicides after the R5 stage of development.

It’s important to call a local county Extension office or the K-State Plant Disease Diagnostic Lab at 785-532-6176 to help you confirm tar spot. Onofre also encourages farmers who suspect they have tar spot to call him at 785-477-0171 to help track the disease.

Read more online at bit.ly/eupdatetarspot.

Kansas State Agronomy eUpdate contributed to this article.

About the Author(s)

Jennifer M. Latzke

Editor, Kansas Farmer

Through all her travels, Jennifer M. Latzke knows that there is no place like Kansas.

Jennifer grew up on her family’s multigenerational registered Angus seedstock ranch and diversified farm just north of Woodbine, Kan., about 30 minutes south of Junction City on the edge of the Kansas Flint Hills. Rock Springs Ranch State 4-H Center was in her family’s backyard.

While at Kansas State University, Jennifer was a member of the Sigma Kappa Sorority and a national officer for the Agricultural Communicators of Tomorrow. She graduated in May 2000 with a bachelor’s degree in agricultural communications and a minor in animal science. In August 2000 Jennifer started her 20-year agricultural writing career in Dodge City, Kan., on the far southwest corner of the state.

She’s traveled across the U.S. writing on wheat, sorghum, corn, cotton, dairy and beef stories as well as breaking news and policy at the local, state and national levels. Latzke has traveled across Mexico and South America with the U.S. Wheat Associates and toured Vietnam as a member of KARL Class X. She’s traveled to Argentina as one of 10 IFAJ-Alltech Young Leaders in Agricultural Journalism. And she was part of a delegation of AAEA: The Ag Communicators Network members invited to Cuba.

Jennifer’s an award-winning writer, columnist, and podcaster, recognized by the Kansas Professional Communicators, Kansas Press Association, the National Federation of Presswomen, Livestock Publications Council, and AAEA. In 2019, Jennifer reached the pinnacle of achievements, earning the title of “Writer of Merit” from AAEA.

Trips and accolades are lovely, but Jennifer says she is happiest on the road talking to farmers and ranchers and gathering stories and photos to share with readers.

“It’s an honor and a great responsibility to be able to tell someone’s story and bring them recognition for their work on the land,” Jennifer says. “But my role is also evolving to help our more urban neighbors understand the issues our Kansas farmers face in bringing the food and fiber to their store shelves.”

She spends her time gardening, crafting, watching K-State football, and cheering on her nephews and niece in their 4-H projects. She can be found on Twitter at @Latzke.

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