Tar spot and white mold on the minds of corn and soybean farmers

A crop protection specialist identifies two crop diseases as the biggest threats to yield this year.

Jason Gibson with Corteva Agriscience says tar spot is the number one disease on the minds of corn farmers, and for soybeans it’s white mold.

“The first thing a person really needs to pay close attention to is weather forecast, particularly during key stages of crop development. For tar spot, we see a lot of tar spot showing up in that milk to dough stage, R2 (and) R3.”

He tells Brownfield tar spot thrives in cool temperatures with high humidity, cloud cover, and extended periods of dew throughout the night.

Gibson suggests many of those characteristics lead to white mold when soybeans are flowering.

“Temperatures in that 60 to 75 Fahrenheit, along with relative humidity greater than 60 percent, and situations where we’re getting some frequent rain events can make soybeans pretty prone to white mold.”

He says the first signs of white mold are gray to white lesions on the soybean nodes, and an early symptom of tar spot is small, raised black dots on corn leaves that turn into round or oval-shaped lesions.

Gibson made these comments during an upcoming Brownfield Managing for Profit program, a content partnership with Corteva Agriscience.

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