The Illinois Agricultural Statistics Service says one-third of the crop had been planted as of Sunday, compared to just nine-percent at the same time last year and the five-year average of 23-percent.
Last week, only six percent of the crop was in the ground.
Corn planting in Illinois is 95 percent finished. That's also well ahead of last year's pace, when 72-percent of the crop had been planted through the first week in May.
Two-thirds of the corn crop has emerged.