Assuming that the average daily planting progress of 4.8 percent in Illinois is representative of the rest of the country and that 14.5 days will be suitable for fieldwork through May 20, an additional 70 percent of the corn crop would be planted by May 20, bringing the total to 74 percent planted. As a result, 26 percent of the crop would be planted late by our definition, about equal to that in 2009. Of course there is no way to know the actual daily planting progress over the next four weeks or how many days will be suitable for field work. In order to reach the average late planting of 15 percent at the average planting progress of 4.8 percent per suitable day, 17 days would be needed. Conversely, if average daily planting progress was at the recent peak rate (2010) of 6 percent and 14.5 days are suitable for fieldwork, only 9 percent of the crop would be planted late.
To avoid having more than the long-term average of 15 percent of the corn crop planted late in 2013 will require some combination of more than the average number of days suitable for fieldwork between now and May 20 and an above average planting rate per day. While the near term weather forecast is for more favorable planting conditions to develop, additional precipitation is expected in the Corn Belt next week. In combination with a lack of sustained seasonal temperatures, the additional precipitation may keep planting progress well behind average a while longer.
To date, the corn market has not reflected substantial concern about the impact of late planting on 2013 average yield potential. December 2013 corn futures have declined by $0.40 over the past month and are at the lowest level since June 2012. Perhaps the corn market has not shown much concern because prices are already at relatively high levels following the short crop of 2012 or because farmers reported intentions to plant more corn acres than needed if yields are at trend level. Alternatively, the lack of response may reflect some overweighting of the 2009 experience. Twenty-nine percent of the corn crop was planted late in 2009, yet the U.S. average yield was above trend value at a record 164.7 bushels. The late planting of 2009, however, was followed by a relatively rare cool, wet summer and an extended growing season that was very favorable for corn yields.