Tassels shedding pollen while still wrapped in the flag leaf is an uncommon occurrence in Iowa and across the Corn Belt. I think I've only seen it once before in my 20+ year career as an agronomist. However, based on conversations with colleagues, it appears to be widespread throughout the region. It does not seem to be brand-specific, but it does appear to be hybrid-specific. We believe this may be a form of rapid growth syndrome occurring at the end of the vegetative stages, likely triggered by a combination of high temperatures, ample moisture, and non-limiting nutrient availability.
Typically, rapid growth is observed during the early to mid-vegetative stages. Over the past decade, hybrids have been bred to synchronize silk emergence with tassel development. While this is usually beneficial, when tassels begin shedding pollen while still wrapped in the flag leaf, it can limit silk receptivity and reduce pollination success.
Here are some of my field observations:
- Affected hybrids tend to have smaller and fewer tassel branches.
- There is a greater presence of secondary ears.
- The issue appears in approximately 20% to 80% of plants (mostly under 50%).
- Ears show anywhere from minimal to 30% non-pollinated ovules.
- Affected fields were generally planted in April.
These observations are based on what I’ve seen in the field, as well as reports and photos submitted by others. They may or may not be directly related to the tightly wrapped tassels.
Take time in the coming weeks to assess pollination success. While there’s nothing that can be done at this stage, understanding pollination outcomes now is far more helpful than trying to diagnose issues at harvest.
We’d like to hear from you!
If you’ve observed wrapped tassels shedding pollen, please let us know your county, the hybrid, and the planting date by filling out our Wrapped Tassel Questionnaire. Your input will help us better understand how widespread this issue is and factors that may be affecting this condition.
Resources:
The Birds and Bees of Corn Pollination
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- Associate Professor
- Extension Cropping Systems Specialist