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Does your corn need sulfur? Test and see

Corn Commentary: Tissue testing can help monitor conditions inside plants. Here’s how to do it.

Tom J. Bechman, Midwest Crops Editor

July 9, 2024

5 Min Read
Striping on corn leaves
SULFUR STRIPING? Note some very light striping, especially on larger leaves. Sulfur can cause striping, but so can other things, including genetic variability. Tissue tests indicated sulfur was low, but likely temporarily. Photos by Tom J. Bechman

Recently, a young woman underwent a medical procedure where specialists went down her throat with a camera to learn why she was experiencing stomach pains. Don’t worry — she was asleep during the procedure. You have a somewhat less invasive way to find out what’s happening inside your corn plants. Twenty plants sacrifice one leaf each for a tissue sample that a lab can analyze.

Like the medical procedure, the tissue sample is a snapshot in time. “Tissue tests provide information that we don’t have by just looking at the plant,” says Dan Quinn, Purdue Extension corn specialist. Quinn provides guidance for the 2024 Corn Commentary project, which follows the progress of a field in central Indiana.

“If you suspect a problem, like a severe nutrient deficiency, pull soil samples too,” he continues. “When possible, pull a tissue sample and soil sample for where you see symptoms, and then from good areas that appear normal.”

Tissue testing also can be used routinely to monitor crop progress on healthy corn. Many agronomists suggest testing at three times: V5, V12 and tasseling. Others who want more information test as often as every week.

Tissue sample example

Two areas within the Corn Commentary field were sampled in late June, with corn approaching V10. It was hot and dry the previous week. “You need to know weather and soil conditions so you can interpret results correctly,” explains Betsy Bower, an agronomist with Keystone Cooperative who works with farmers in west-central Indiana. Keystone Cooperative covered shipping and lab costs for these samples, tested at SureTech Labs in Indianapolis.

Related:Not too late to assess planter performance

Because corn appeared healthy, only tissue samples were pulled. Slight striping was evident. Could sulfur be limiting, even though the grower indicated sulfur was applied three different times?

Folded corn leaves on a bed of a pick up truck

As it turned out, sulfur was low, but the nitrogen-to-sulfur ratio was still adequate, Bower notes. Nitrogen, potassium and phosphorus all were barely in the deficient range, even though plants were not showing visible symptoms. All other nutrients and micronutrients were in healthy ranges.

“Here’s where you must interpret circumstances,” Bower says. “It was very dry, and these plants were into a grand growth phase. Under those conditions, it’s not unusual for plants to test low in major nutrients, because demand is high, and roots aren’t operating at peak efficiency. Nutrients like sulfur are likely in the soil, but plants can’t get them. It’s likely a temporary situation.”

Rain followed and temperatures moderated. Corn still appeared healthy two weeks after sampling. “This is why we monitor and test through the season,” Bower explains. “Right now, it appears the field is in good shape. It will be interesting to see how major nutrient levels appear later, especially if weather conditions are more favorable.”

Related:Why isn’t my corn green?

Across the rows:
Not one world for U.S. corn crop in ’24

Grain traders didn’t take kindly to finding out more corn acres were planted than they thought. Prices dipped on June 28, even though thousands of acres were destroyed by flooding in parts of the Corn Belt, and other areas remained dry. The fate of hundreds of thousands of acres remains uncertain, and crop conditions for corn across the Midwest are “variable” at best. Here is a snapshot:

In Minnesota. “Water, water, everywhere. Crops that haven’t been decimated by extensive rains are in various stages and phases, from prevent plant, replant, shoulder- or head-high to poor stands.

“Talking with the state ag commissioner, he observed that it may be tough to get a 30% countywide crop disaster declaration [in individual counties] because not all land has been flooded by waterways or lakes. However, they will be applying for whatever aid is available to help farmers. Stay tuned.” — Kevin Schultz, editor of The Farmer

In Illinois. “It was another dry, hot week in LaSalle County. There were some showers on Tuesday [June 25], but not enough to make a huge difference. Despite this, crops are only showing minimal signs of stress.

“I spotted our first western corn rootworm beetle this week, but overall the field isn’t experiencing much pest pressure. Some much-needed rain and cooler temperatures are in the forecast for later this week and next, which will hopefully alleviate some of the issues we’re seeing and speed up crop growth.” — Emily Hansen, LaSalle County Commercial Extension educator, last week of June, as reported in The Bulletin Illinois Extension Update, FarmDoc

In Iowa. “Four-inch hail wiped out lots of acres in a mid-June storm in western Iowa, causing some fields to be replanted, including some seed corn fields.” — Beck’s sources (Editor’s note: Significant hail damage was also reported in Henry County, Ill., through FarmDoc sources.)

In Ohio. “While western bean cutworm scouting numbers are currently low, it is still important to be ready for these pests in Ohio, and scouting is the best way to stay ahead of any infestations before they happen.

“This is our third week of monitoring for corn earworm pests in Ohio. The statewide average for CEW increased from 0.12 during the week ending on June 16 to 1.6 for the week ending June 23. Counties with the highest averages included Williams, Clinton and Morgan. These moths are attracted to fields that are in the early green silk stage of development, when fields will be most susceptible to damage.” — Lep Monitoring Network reports in the Ohio Agricultural Research and Development Center’s C.O.R.N Newsletter, June 24 edition

Read more about:

Tissue Testing

About the Author(s)

Tom J. Bechman

Midwest Crops Editor, Farm Progress

Tom J. Bechman became the Midwest Crops editor at Farm Progress in 2024 after serving as editor of Indiana Prairie Farmer for 23 years. He joined Farm Progress in 1981 as a field editor, first writing stories to help farmers adjust to a difficult harvest after a tough weather year. His goal today is the same — writing stories that help farmers adjust to a changing environment in a profitable manner.

Bechman knows about Indiana agriculture because he grew up on a small dairy farm and worked with young farmers as a vocational agriculture teacher and FFA advisor before joining Farm Progress. He works closely with Purdue University specialists, Indiana Farm Bureau and commodity groups to cover cutting-edge issues affecting farmers. He specializes in writing crop stories with a focus on obtaining the highest and most economical yields possible.

Tom and his wife, Carla, have four children: Allison, Ashley, Daniel and Kayla, plus eight grandchildren. They raise produce for the food pantry and house 4-H animals for the grandkids on their small acreage near Franklin, Ind.

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