Michigan corn tar spot remains a concern even as recent rainfall delivered a timely boost to fields across Michigan and northern Indiana, according to an agronomist who reported localized totals of up to four inches.
Charles Scovill of Golden Harvest said the precipitation arrived at a critical point as corn finished pollination and began kernel set. He described the event as what some might call a “one million dollar rain.”
Scovill noted that overall crop condition looks favorable. Planting was slightly delayed, he said, but the crop has been catching up and disease pressure is currently relatively low.
Growers are weighing fungicide applications as they keep a close watch on tar spot this season. Scovill said the disease has been confirmed in eight Michigan counties and that recent weather has been conducive to its development.
He said cooler conditions paired with moisture support infection, adding that the disease typically takes about 21 days from initial infection to visible symptoms. Based on recent weather, he said it would not be surprising to see additional tar spot symptoms emerge in the next couple of weeks.
Michigan corn tar spot and crop ratings
In its latest crop progress report, the U.S. Department of Agriculture rated Michigan’s corn at 67 percent good to excellent, with 37 percent of the crop in the dough stage. The state’s soybean crop was rated 51 percent good to excellent, with more than half of fields setting pods.
Growers considering fungicide strategies for tar spot may also be watching developments like peptide-based biofungicide approvals as new tools emerge in the market.