Dr. Joe Lauer, UW-Madison Agronomy and UWEX state corn specialist, has added a new article to his blog. Below, find an excerpt and link to his website.
Figure 1. Wisconsin corn planting progress from 1987 to 2017. The bold blue line is the 30-year normal. Other lines are years that were earlier- or later-than normal using + one standard deviation. Click figure to enlarge.