Gray Leaf Spot Attacking Kansas Corn

Gray leaf spot is exploding in eastern Kansas, causing concerns about a possible epidemic.

Gray leaf spot, a potential yield-robbing disease, has surfaced in east Kansas corn fields, heightening the need for producers to scout their acreage, a Kansas State University plant pathologist says.

Levels of the disease have exploded recently in the eastern half of the state. “Much of the corn in the west is just starting to reach the maturity stage when gray leaf spot needs to be monitored,” says Doug Jardine, plant pathology state leader with K-State Research and Extension.

Jardine scouted numerous corn fields in the western half of the Kansas River Valley the first week in July. Growth stages there ranged from tassels just emerging to pollen shed. “In nearly every field, gray leaf spot lesions could be found within one to three leaves of the ear leaf. In a couple of fields, lesions were already present above the ear leaf,” Jardine says. “It is my understanding that fungicide applications have begun. Still, every field should be checked for gray leaf spot progress and development.”

Jardine surveyed southeast Kansas July 17-18 and found the corn there looks healthy, with little evidence of gray leaf spot. “Most of the corn in southeast Kansas is mature enough that gray leaf spot is likely not to be a problem for the remainder of the season,” he says.

For fields where the disease is already above the ear leaf, Jardine says grower-customers should consider using a triazole or triazole-containing fungicide, such as Quilt, Stratego, Tilt, Bumper, or Propimax. In fields where the disease has made less progress, strobiluron fungicides such as Headline or Quadris can work well.

“The most severe disease outbreaks will occur where susceptible hybrids are being grown in a corn-after-corn or no-till situation,” the plant pathologist says.

Growers can estimate returns that may come from applying a fungicide to a field with heavy gray leaf spot, Jardine says. With the following formula, for example, a grower might use these assumptions: Yield potential of 110 bushels per acre; fungicide application at a cost of $22 per acre; gray leaf spot at or above the ear leaf; and a selling price of $7 per bushel:

  • 5 percent loss to disease = ~ $16 net return
  • 10 percent loss to disease = ~ $53 net return
  • 15 percent loss to disease = ~ $90 net return
  • 20 percent loss to disease = ~ $129 net return

Higher yields would result in higher net returns, Jardine adds

Leave a Reply

Latest News
Eric SfiligojMonsanto ‘Picks Its Battles’ by Nixing Deere Deal
May 23, 2017
Having been in the trade journalism game since the mid-1980s, I remember several watershed moments during my career. One of Read More
FungicidesSyngenta Launches New Seed Treatment Fungicide
May 22, 2017
Syngenta has announced the launch of PLENARIS seed treatment fungicide for the control of downy mildew in sunflower. PLENARIS contains Read More
Corn close up
Crop InputsMonsanto’s First HPPD Herbicide Garners EPA Appro…
May 19, 2017
Monsanto announced today that EPA has federally approved Harness MAX Herbicide, the first herbicide in the Monsanto portfolio to provide Read More
ManagementPrecision Planting Deal, China Developments, and Enviro…
May 18, 2017
Editors Eric Sfiligoj and Dan Jacobs discuss the latest news on John Deere’s now dead deal for Precision Planting, China’s Read More
Soybean aphid leaf
InsecticidesMulti-state Research Reveals IPM Best Option for Treatm…
May 17, 2017
About 89.5 million acres of soybeans will be planted across the U.S. in 2017 — a record high, according to Read More
GROWMARK-2017-Interns
CropLife 100GROWMARK Names 2017 Summer Interns
May 16, 2017
Forty-two college students are exploring agricultural career opportunities this summer as GROWMARK interns. They are working at FS member cooperatives Read More
Migrant farm workers
LegislationTrump: Immigration Crackdown Won’t Impact U.S. Ag…
May 16, 2017
President Donald Trump said he would seek to keep his tough immigration enforcement policies from harming the U.S. farm industry Read More
Flooded corn in Indiana
FertilizerBoth Wet and Dry Conditions Threaten Nitrogen Loss
May 15, 2017
The weather is notoriously unpredictable, leading to challenges for planting, harvesting and applying the nitrogen (N) your corn crop needs. Read More
farmer Kip Tom
Precision AgAg Tech: On the Cusp of Something Big?
May 15, 2017
The investment and ag-tech sectors’ continuing courtship of agriculture, smoldering for three or four years now, was well in evidence at Read More
AGCO Ratliff featured
Eric SfiligojRemembering Robert Ratliff
May 15, 2017
With all the fast-paced happenings in agriculture this spring, with multiple mergers in the works and planting season in full Read More
Greg Musson, Gar Tootelian
ManagementOpinion: Shaking Your Perspective in Ag Retail
May 12, 2017
Some of you I’m sure have encountered our recently retired salesman extraordinaire, Dan Bellanger. He worked in the industry for Read More
Exterior view of CPS Big Lake facility which includes enclosed receiving and load out area
CropLife 100New Alternative Weed Resistance Traits Could Experience…
May 12, 2017
It wasn’t too many years ago that ag retailers and their grower-customers could hardly wait for new options to fight Read More
Diane Allemang and Dan Jacobs
Crop InputsFMC Agricultural Solutions, Casa Pacifica Partner to He…
May 11, 2017
FMC Agricultural Solutions is teaming up with Casa Pacifica Centers for Children and Families, an organization that supports vulnerable children Read More
UncategorizedWhat’s Up With ARA
May 11, 2017
CropLife Editor Eric Sfiligoj talks with Brian Reuwee regarding what issues are on the docket for the Agricultural Retailers Association. Read More
BASF Maglis tablet retailer grower
Precision AgQ&A: What BASF’s Latest Foray into Precision …
May 11, 2017
In late April, BASF agreed to acquire U.S. precision ag player ZedX, a leader in the development of agronomic weather, Read More
Pam Marrone
Crop InputsMarrone Bio Innovations Enters into Distribution Agreem…
May 11, 2017
Marrone Bio Innovations, Inc., a leading global provider of bio-based pest management and plant health products for the agriculture markets, Read More
Bayer
Crop InputsBayer to Sell Liberty Business to Seal Monsanto Deal
May 8, 2017
Bayer has agreed to sell its Liberty herbicide and LibertyLink-branded seeds businesses to win antitrust approval for its acquisition of Read More
Trump, Senate, Cabinet
LegislationTrump’s EPA Appointee Dismisses Half of Major Sci…
May 8, 2017
(Via NYTimes.com) EPA has dismissed at least five members of a major scientific review board, the latest signal of what Read More