Tar Spot, a new disease infecting corn, is spreading across Ontario, raising concerns that it could eventually be as damaging as in the areas of the United States where it first showed up, blown in from Mexico on storm winds.
It has shown up in Southern counties the last two years and this year it’s in Wellington, Grey and Bruce.
It looks like black insect poop, but can be distinguished with a spit test – wetting and rubbing because only poop comes off.
Tar spot is taking a toll on corn crops in parts of Illinois this week, said Ken Ferrie, Farm Journal Field Agronomist and owner of Crop-Tech Consulting at Heyworth, Ill.
“In a number of fields, not only have the wheels come off the bus, but it's sliding down the highway on its frame and the sparks are flying,” he said.
What Ferrie is seeing with tar spot in some fields is unprecedented. Heavily infected fields, particularly those with D hybrids, have been dying.
“Fields that had a decent amount of green went dead-brown in seven to 10 days,” he said. “The corn all died early, most of it before reaching black layer.