Last week’s warmer weather helped speed planting in parts of the Corn Belt, while excessive rain limited opportunities for fieldwork in the central Plains and much of the Midwest, the National Corn Growers Association (NCGA) says.

Figures from the U.S. Department of Agriculture National Agricultural Statistics Service show corn planting advanced 30 percentage points to 53 percent complete, behind last year’s 67 percent and the historical 63 percent average. Good progress was made during the week throughout many areas. By week’s end 72 percent of Illinois’ corn crop had been planted, and Minnesota and Wisconsin showed near-normal planting figures. By contrast, long periods of rain delayed planting in Indiana, Iowa, Kansas, Missouri, Nebraska and Ohio. By May 6, 14 percent of the crop had emerged, compared with 23 percent last year and the 20 percent average.

Corn planting is entering a critical stage, NCGA notes. University research in a number of states cautions that when planting is delayed past an optimal time in spring, yields may decline.