Tar spot found in southeastern Michigan
Tar spot has now been confirmed in Michigan.
Michigan State University plant pathologist Marty Chilvers says low levels have been reported in the southeastern part of the state in Monroe County.
“I’m completely not surprised, given that we’ve had rainfall events, at least the past three weeks now, if not a little bit longer,” he says.
Chilvers says research has found the timing of fungicides is most effective once corn starts to tassel rather than in earlier vegetative stages.
“Because it’s too early, tar spot is not there yet,” he says. “Those fungicide products are going to wear off and you’re not going to get the control that you need.”
Chilvers says added moisture in the soil has been causing dew formation which can also encourage tar spot development. He expects more outbreaks to be reported in the coming days and weeks since the disease has a history across much of the state.
Chilvers recommends farmers use a spit test to help identify the disease when scouting for it. He says the disease can be confused with bug poop and if black spots cannot be rinsed off plants and are imbedded in the plant, it’s likely tar spot.
Tar spot has also been confirmed in Indiana, Iowa, Kansas, Missouri, and Nebraska in the past few weeks.