In the last two weeks, there have been localized reports of tight tassel wrap in corn, where the tassel remains bound by the flag leaf (Figure 1). This condition can interfere with pollen shed and lead to poor kernel set in some cases.
Tight tassel wrap has been observed mostly in fields planted during the week of April 28. Fields planted during this window experienced the first heat wave (three consecutive days with high temperatures of 90°F or warmer) starting June 21or approximately 55-61 days after planting (Figure 2). This surge in temperature was then followed by high rainfall in most areas of the state. We speculate that the combination of high temperatures and moisture led to rapid vegetative growth and pollen shed prior to complete tassel emergence.
Tight tassel wrap has also been observed in other states, including Iowa and Indiana. Thus far, it is specific to planting date and more common in certain hybrids, but not brand specific. The good news is that recent rainfall over the weekend will alleviate symptoms, and assuming not all tassels in a field are affected, the remaining good tassels should be able to spread enough pollen to mitigate potential pollination issues. A normal tassel can produce about 3-5 million pollen grains and normally a corn plant can have about 1,000 ovules or potential kernels. If there is not enough pollen in the field, be on the lookout for possible incomplete kernel set or other abnormal ear symptoms (i.e. double ears) later this season in affected fields.