Tight Tassel Wrap Is Showing Up in the Corn Belt — Here’s What Farmers Should Know

As the U.S. corn crop progresses through some of its most critical stages of development, something unusual is unfolding — not beneath the surface, but rather, beneath the leaves.

The nation’s corn crop is in great shape: 74% was rated good/excellent by the USDA for the third straight week. Yet, a phenomenon called tight tassel wrap has been reported in several of the top corn-growing states, and it’s something that has the potential to impact overall yield.

What Is It?

With tight tassel wrap, corn tassels remain tightly wrapped in the upper leaves of the corn plant and fail to shed pollen properly, according to Kansas State University (KSU) agronomists Kraig Roozeboom, Tina Sullivan, and Logan Simon. Ultimately, this has the potential to cause pollination issues that lead to poor kernel set, they said.

“Unpollinated silks continue to grow and may reach several inches in length and still be receptive to pollen for several days,” the agronomists said. “However, these long silks can block pollen from reaching later-emerging silks and will eventually cease to be receptive to pollen, especially when temperatures reach the upper 90s and above.”

Roozeboom, Sullivan, and Simon said that although the impact of delayed pollination is hard to predict, any delay usually does not bode well for yield formation.

Why Is It Happening?

Tassels releasing pollen while still wrapped is uncommon in Iowa and throughout the Corn Belt, said Mark Licht, associate professor and Extension cropping systems specialist with Iowa State University Extension and Outreach. He’s only seen it one other time in his more than 20 years in agronomy. 

“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,” Licht explained.

Hybrids have been bred to synchronize silking with tasseling, which is usually beneficial, Licht said. But if tassels start releasing pollen while still wrapped, silk receptivity may be limited and pollination success can be reduced.

As Eric Wilson, an Iowa agronomist with Wyffels hybrids, explained,“Generally, [tight tassel wrap] is a good thing and can help in successful pollination during stressful conditions. However, this year it is resulting in some pollination issues.”

Where Is It Causing Issues?

Tight tassel wrap has been reported in various states across the Corn Belt. Here’s a look into how crops in Illinois, Iowa, Kansas, Nebraska, and Ohio are being impacted.

Illinois

“I have gotten tons of pictures and phone calls about tassel wrap in the last week,” Ryan Gentle said on Monday. He’s a Wyffels agronomist supporting much of the western half of Illinois. “It, unfortunately, is happening in some very high volume competitive products across central Illinois,” he said. 

Gentle said the corn impacted was planted April 15–25 and May 5–8. The issue’s popping up from eastern Iowa to as far west as the Champaign area, and from Cissna Park to south of Springfield, north to south, he said.

“It seems to be affecting anywhere from 10–40% of the ears in a field,” Gentle said. “I am seeing anywhere from 10–60% of the kernels missing on these ears. It will have a big impact on yield in the worst damaged fields.”

Phil Krieg, a Syngenta agronomist whose territory is further south in Illinois, said he’s heard scattered reports but has not been called into any field to inspect.

Corn Crop Progress and Condition

As of July 20, 79% of Illinois’ corn crop had reached the silking stage, ahead of the 76% five-year average, while 15% had reached the dough stage, ahead of the 13% five-year average. The USDA rated 70% of the crop good/excellent, 22% fair, and 8% poor/very poor.

Iowa

In his coverage area of southern and northeast Iowa, Wilson is seeing pollination issues related to tassel wrap and stressful conditions in corn that was planted April 10–15. “These planting dates pollinated under some very warm conditions, which likely affected pollen viability and caused some silks to emerge early ahead of pollen shed,” Wilson said on Sunday.

The issue is fairly widespread, Wilson shared, but not all hybrids are affected. “It is fairly specific to certain hybrids and specific planting dates,” he said.

Licht outlined some of his 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%–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,” he said.

Corn Crop Progress and Condition

By July 20, 62% of Iowa’s corn crop was silking, behind the 63% five-year average, and 18% had reached the dough stage, seven points ahead of average. The USDA rated 86% of the crop good/excellent, 11% fair, and 3% poor/very poor.

Kansas

According to KSU’s Roozeboom, Sullivan, and Simon, tight tassel wrap in the Kansas crop seems to be linked to the mid-April planting window. “There could be instances where a hybrid with tassel wrap and reduced pollination shows normal tassel emergence and ear development in fields planted outside of that window,” the agronomists said.

Corn Crop Progress and Condition

As of July 20, 61% of Kansas’ corn had reached the silking stage, behind the five-year average of 64%, while nearly a quarter, or 24%, had reached the dough stage, ahead of the 21% average. USDA rated the state’s corn crop 64% good/excellent, 27% fair, and 9% poor/very poor.

Nebraska

“We’ve seen a few reports here and there about wrapped tassels in Nebraska,” said Travis Gustafson, a Syngenta agronomist in Nebraska. “It’s been very sporadic and in pockets.”

Overall, the Cornhusker State’s crop has seen some “absolutely ideal growing conditions,” Gustafson shared. He said corn is pretty much fully tasseled and conditions for pollination are excellent.

Corn Crop Progress and Condition

The USDA said that 56% of Nebraska’s corn had reached the silking stage, a noteworthy eight points behind the five-year average. Ten percent had reached the dough stage, though, which was two points ahead of normal. The agency rated 78% of the state’s crop good/excellent, 18% fair, and 4% poor/very poor.

Ohio

Ohio’s had localized reports of tight tassel wrap, and it’s been seen primarily in corn that was planted during the week ending May 4. Here’s what Ohio State University Extension had to say about how it likely occurred: 

“Fields planted during this window experienced the first heat wave (three consecutive days with high temperatures of 90°F or warmer) starting June 21, or approximately 55–61 days after planting. 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.”

Corn Crop Progress and Condition

In Ohio, 40% of the corn crop had reached the silking stage by July 20, just shy of the five-year average of 41%. Six percent had reached the dough stage, ahead of the 4% five-year average. Just 59% of the state’s corn was rated good/excellent, while 35% was rated fair and 6% was rated poor/very poor. 

What Can Farmers Do?

Although there is nothing that can be done to correct the issue, it’s a good idea to scout fields and evaluate the kernel set to start to understand the potential yield impact, according to the KSU agronomists.

“This is especially important in fields that experienced rapid growth earlier this growing season,” Roozeboom, Sullivan, and Simon said. “Performing yield estimates can help inform decisions about subsequent inputs, like fungicides, if the yield estimate is well below the target.”

As Licht said, “Understanding pollination outcomes now is far more helpful than trying to diagnose issues at harvest.”