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Tar spot’s rapid spread west continues

A crop specialist with BASF says weather can dictate where tar spot develops.

Gary Schmitz tells Brownfield the disease is becoming more prevalent in areas of the Western Corn Belt. “Where we have wetter weather, where the leaves will stay wet for more than 7 hours, is typically where we see the hot spots that show up.”

He says timely fungicide applications are critical for management. “Plan for that application in the VT to R1 timing. You’ll get out there normally ahead of the disease but you’re going to have to make sure you’re monitoring for the disease.”

Schmitz says tar spot progresses quickly and can completely cover plants in as little as two weeks. “Depends on the year, but we’ve seen places where there has been 50 bushel loss if you don’t treat for the tar spot.”

Tar spot overwinters on corn residue and the spores can blow in from neighboring fields.

Schmitz (pictured above) spoke to Brownfield at a recent field day at BASF’s Showcase Plot near Story City, Iowa.