Tar spot a top concern for farmers, survey shows

WESTFIELD, Ind. — Over half of nearly 400 farmers surveyed this fall cited tar spot when asked about diseases that may impact corn in their area, according to a study commissioned by AgReliant Genetics and conducted by Kynetec.

Farmers’ tar spot concern eclipses worry about other diseases like northern corn leaf blight, southern rust and Goss’s wilt — especially in states where tar spot is prevalent, including Indiana.

Fifty-six percent of farmers in high-risk states are very or extremely concerned about the disease, followed by northern corn leaf blight at 28%.

While concern about tar spot is high, survey results indicate farmers lack clear direction on how to manage the disease.

“Our first finding is that tar spot is the No. 1 corn disease on farmers’ minds and their concern over it is growing year over year,” said Christy Toedebusch, vice president of digital product and marketing, at the AgReliant Tar Spot Summit.

“The second finding is that tar spot is impacting farmers’ yields and overall profitability. Farmers are unclear, however, on how to manage it.

“Finally, when it comes specifically to making choices about corn hybrids on their farm, three out of four farmers plan to use a tar spot tolerant hybrid in 2023 and more than half agree that diversifying genetics on your operation more holistically helps to mitigate disease risk.”

Despite a relatively dry growing season in 2022 that limited tar spot impact, 71% of farmers surveyed expressed heightened concern about the disease, primarily due to its rapid spread.

When asked for additional comments, one respondent said: “Tar spot has been found within 20 miles of our farm, and we know the disease can be catastrophic.”

Another commented that tar spot “has recently appeared in our area and had tremendous negative yield effect.”

The survey found half of the respondents had detected tar spot on their land at least once, with 90% of those hit by tar spot experiencing yield loss.

Uncertainty

While farmer awareness and concern about tar spot is high, the survey also revealed uncertainty about the disease mechanism and how to manage it.

A third of the respondents had a good understanding of tar spot’s yield impact. However, data shows that only:

• 16% said they understand how it overwinters.

• 17% understand how it spreads or under what conditions.

• 13% understand hybrid tolerance or tolerance ratings.

• 17% understand fungicide efficacy.

Most farmers plan to use a combination of strategies to fight tar spot, including rotating crops, scouting and planting hybrids with high tar spot tolerance.

“Genetic diversity provides critical protection against the weather and disease threats, tar spot included,” said Mike Kavanaugh, director of product development at AgReliant.

“When you plant a diverse array of hybrids that may respond differently to different weather or disease challenges, you spread your risk.

“Tar spot is an opportunistic disease that attacks weaker plants, which is why it’s so important to make diverse genetics a part of any tar spot management strategy.”

In A Nutshell

• Tar spot is the No.1 corn disease on farmers’ minds — and their concern is growing.

• Tar spot is impacting farmers’ yield and profitability.

• Farmers are unclear about the best management practices to manage tar spot.

• Three in four farmers plan to use a tar spot tolerant hybrid in 2023. More than half agree that diversifying genetics mitigates disease risk.