During the past week, tassels began appearing in corn fields that were planted in late April and early May. However the pollination period is going to vary widely across the state this year.
According to the National Agricultural Statistics Service ( http://www.nass.usda.gov/oh/ ), about a third of our corn acreage was planted on or before May 4, then due to persistent rainy conditions, another third of our corn was planted over the next three weeks, and the remaining third of our acreage was planted (or replanted) in late May and early June. The late planted corn will not be tasselling until early to mid August. The pollination period, the flowering stage in corn, is the most critical period in the development of a corn plant from the standpoint of grain yield determination. Stress conditions such as drought or hail damage have the greatest impact on yield potential during the reproductive stage. The following are some key steps in the corn pollination process. For more on corn pollination click ...http://corn.osu.edu/#C
Another good source of information is the following: http://www.agry.purdue.edu/ext/corn/news/timeless/Tassels.html