Rootworms Show Resistance To Bt Corn

Isolated findings of resistant rootworms in Iowa emphasize that planting a refuge is more critical than ever for maintaining the durability of Bt corn, a Purdue Extension entomologist says.

Bt corn does not kill all larva that feed upon it, and very slight feeding damage from corn rootworm is typical, said Christian Krupke. But after researchers at Iowa State University were alerted to high levels of feeding damage in some fields, they began to test Bt corn hybrids that expressed the Cry3B1 toxin. They found that rootworms from those fields were able to survive exposure in the lab.

“This is not a cause for alarm for Indiana producers, and it was something that we suspected would occur eventually,” Krupke said. “Producers should keep doing what they are doing for now as the vast majority of Bt continues to perform well for producers. This is more of a warning to be vigilant.”

Currently, other Bt toxins appear to be effective against the pest.

He said growers in areas with histories of high rootworm pressure should scout fields in early to mid-July to look for lodged corn and adults, which are gold and black beetles. Farmers seeing anything unusual should dig up the plants and look for root damage. By August or later, roots can regrow and disguise damage.

If farmers see widespread damage, they should contact their seed representatives to determine if their corn was supposed to be protected by the Bt technology.

“Producers should only be more concerned if there is considerably more damage than usual,” Krupke said. “Also, it’s worth a second look to ensure they aren’t looking at refuge plants instead of the hybrid.”

Growers who think they have a potential problem should report it to their Purdue Extension county educators. All farmers should follow best management practices when using any hybrid varieties targeting pests.

The most important thing corn growers can do this season and in the future is follow refuge guidelines, Krupke said. Refuges develop a population of susceptible adults and allow mating between those and any potentially resistant beetles that emerge from Bt plants. Compliance with refuge recommendations has declined in recent years.

“The refuge is crucial as the Bt hybrids do not kill all larva; some will inevitably become adults. We don’t want those survivors to mate with one another and pass on the traits that helped them survive,” Krupke said. “By limiting the number of mating adults we have, we can hopefully dilute the genetics of these resistant individuals and prevent the population from becoming resistant.”

Rotating with soybeans, and diversity in cropping systems in general can also delay resistance. Fields with continuous Bt corn and high rootworm pressure should be closely monitored, as they provide the greatest pressure for resistance development.

For more information and a link to the Iowa State article, read the Aug. 5 issue of Purdue Pest and Crop Newsletter at http://extension.entm.purdue.edu/pestcrop/.

(Source: Ag Answers)

Leave a Reply

Seed/Biotech Stories

Monsanto sign
Crop InputsCould a Monsanto-Bayer Union Be 2 Weeks from Fruition?
August 24, 2016
Via STLToday.com (The St. Louis Post-Dispatch): Merger talks between Monsanto Co. and Bayer AG are advancing after a series of Read More
Seed/BiotechMycogen Seeds Research Station Celebrates 30th Anniversary
August 9, 2016
The Mycogen Seeds research station in Mount Vernon, IN, is celebrating 30 years of corn hybrid innovation. To mark the Read More
Peanut field
Crop InputsVerdesian Introduces New Inoculant For Peanuts
July 28, 2016
As planning begins for the next growing season, Verdesian Life Sciences adds Primo Power CL, a new liquid inoculant, to Read More
Soil Young Corn
Crop InputsSmithsonian: 5 Things to Know About New GMO Labeling Bill
July 27, 2016
On July 14, the House of Representatives passed a bill requiring large food companies to label products containing genetically modified Read More
Trending Articles
ASMARK 2016 Retailers Live! Tour - CPS
CropLife 100CPS Acquires Texas Retail Operation
August 23, 2016
Crop Production Services (CPS) has acquired the assets of Larry’s Chemical and Spray, Inc., for an undisclosed amount in an Read More
Key Cooperative Marcus Construction Steel Building
Retail FacilitiesMarcus Construction Builds High-Speed Agronomy Center For Key Cooperative
July 7, 2016
Key Cooperative in Grinnell, IA, wanted a state-of-the-art Agronomy Center to better serve its customers. Marcus Construction delivered exactly that. Read More
Heritage Cooperative
Retail FacilitiesKahler Automation Designs State-Of-The-Art Facility For Heritage Cooperative
July 4, 2016
Heritage Cooperative in Marysville, OH, needed an efficient liquid, dry and grain facility to serve the many needs of their Read More
The Andersons Waterloo
ManagementFirst Indiana Facility Certified Under 4R Nutrient Stewardship Certification Program
June 27, 2016
The 4R Nutrient Stewardship Certification Program has announced that The Andersons, Inc.’s Waterloo, IN, facility has been added to its Read More
Food IT
Industry NewsCalifornia Event Will Mix Ag And Tech Professionals To Explore IT Solutions
June 20, 2016
Silicon Valley is hot on agriculture, and an upcoming event in California will bring together the food and tech industries Read More
Monsanto Luling Plant
Eric SfiligojWhat’s Next For Monsanto?
May 31, 2016
For the folks at Monsanto’s headquarters in St. Louis, MO, it has been an eventful few weeks. Back on May Read More
Latest News
2016 ShowStopper | Case IH Patriot 4440 Sprayer
Equipment5 Show-stopping Products On Display At 2016 MAGIE
August 26, 2016
For 10 years now, visitors to the yearly Midwest AG Industries Exposition (MAGIE) show have been tasked with voting for Read More
Crop InputsDuPont Pioneer: Corn Belt P and K Levels Lagging
August 24, 2016
A new DuPont Pioneer study conducted across 12 Corn Belt states demonstrates that growers may be leaving profit potential in Read More
Monsanto sign
Crop InputsCould a Monsanto-Bayer Union Be 2 Weeks from Fruition?
August 24, 2016
Via STLToday.com (The St. Louis Post-Dispatch): Merger talks between Monsanto Co. and Bayer AG are advancing after a series of Read More
EquipmentCase IH Debuts Nutri-Tiller 955 Strip-Till Applicator
August 24, 2016
With strip-till continuing to expand across new acres, Case IH designed the new Nutri-Tiller 955 strip-till applicator to help producers Read More
EquipmentCase Launches Aim Command FLEX, 25th Anniversary Patrio…
August 24, 2016
Case IH announces new AIM Command FLEX advanced spray technology for greater application accuracy, as well as special 25th Anniversary Read More
ASMARK 2016 Retailers Live! Tour - CPS
CropLife 100CPS Acquires Texas Retail Operation
August 23, 2016
Crop Production Services (CPS) has acquired the assets of Larry’s Chemical and Spray, Inc., for an undisclosed amount in an Read More
PrecisionAg Video Conference
Precision AgVideo: PrecisionAg Vision Conference
August 22, 2016
A Strategic Conference Focused on the Future of Farm Digitization and Precision Agriculture Visit precisionagvision.com and register today! Read More
Young Corn Plants
Industry NewsOABA Welcomes Nicole Wallace As Communication & Adm…
August 22, 2016
The Ohio AgriBusiness Association has hired Nicole Wallace as its communication and administrative coordinator. Wallace will help provide comprehensive communication Read More
Syngenta Sign
Crop InputsChemChina, Syngenta Receive Clearance From CFIUS
August 22, 2016
China National Chemical Corp. (ChemChina) and Syngenta have announced that the companies have received clearance on their proposed transaction from the Read More
ManagementAg Industry Shows and Rumors
August 18, 2016
Editors Paul Schrimpf and Eric Sfiligoj talk about the upcoming trade show schedule, crop protection merger updates, and content for Read More
MAGIE 2015
EquipmentMAGIE Takes The Pulse Of The Ag Retail Industry
August 18, 2016
Every year, one of the major highlights of my career as an ag journalist is attending the Midwest AG Industries Read More
MAGIE 2015 Overview
EquipmentPride In Professionalism On Display At MAGIE
August 18, 2016
The Illinois Fertilizer & Chemical Association (IFCA) is proud to partner with CropLife IRON and continue the tradition of bringing Read More
SprayersJenner Ag To Debut 25th Anniversary Edition Case IH Pat…
August 18, 2016
Visitors at the 2016 Midwest Ag Industries Exhibition (MAGIE) in Bloomington, IL, will have a unique photo opportunity, as Jenner Read More
Crop InputsEU Glyphosate Controversy Heating Up Yet Again
August 17, 2016
The battle over glyphosate rages on in Europe, creating a lot of question marks over whether the herbicide will continue Read More
Industry NewsNew Partnership Provides Improved Representation At Ohi…
August 16, 2016
The Ohio AgriBusiness Association (OABA) has retained Belinda Jones of Capitol Consulting Group, Inc. (CCG) for government relations work in Read More
Tissue testing
FertilizerMosaic: 6 Tips For Better Crop Nutrition In Corn
August 16, 2016
Late in the crop season is a good time to assess visual nutrient deficiencies and ensure early- and mid-season deficiencies Read More
WebinarsWebinar Schedule
August 14, 2016
Register for one of our upcoming Webinars or access our archive of past Webinars to view recordings of presentations that may be of interest to you. Read More
Dow DuPont
Crop InputsDowDuPont Update: EU Takes Closer Look at Merger
August 12, 2016
Dow Chemical Co. and DuPont Co. face months of haggling with European Union antitrust regulators who opened an in-depth probe Read More