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

dicamba, Roundup Ready 2 Xtend
Crop InputsASA: No Dicamba On Roundup Ready 2 Xtend In 2016
May 16, 2016
While Roundup Ready 2 Xtend (RR2X) are tolerant to dicamba and glyphosate herbicides, no dicamba herbicides will be approved for Read More
Crop InputsGMO Pipeline Features Consumer Targeted Modifications
April 15, 2016
The newly approved GMO Simplot Innate potato, developed to produce lower amounts of the harmful-yet-natural chemical acrylamide, resist bruising, and Read More
Crop InputsReuters: Chinese GMO Seed Espionage Making Iowa Farmers Uneasy
April 12, 2016
Tim Burrack, a northern Iowa farmer in his 44th growing season, has taken to keeping a wary eye out for Read More
Peanut field
FungicidesArysta LifeScience Receives EPA Approval Of Fungicide Seed Treatment
April 5, 2016
Arysta LifeScience North America recently announced it received approval from the EPA of RANCONA V PD, a broad-spectrum fungicide dust Read More
Trending Articles
Monsanto Luling Plant
Crop InputsReport: Bayer Eyeing Monsanto For Possible Mega-Merger
May 16, 2016
Bayer AG is exploring a potential bid for U.S. competitor Monsanto Co. in a deal that would create the world’s Read More
Aerial Drone
Precision AgA Deeper Dive Into The Future Of Precision Ag
May 9, 2016
For about two decades now, through the good and the bad times, the ups and the downs inherent in agriculture, Read More
Palmer amaranth in soybean stubble
HerbicidesWSSA: Billions In Potential Economic Losses From Uncontrolled Weeds
May 4, 2016
What losses would corn and soybean growers experience if they were forced to eliminate herbicides and other control techniques from Read More
Eric SfiligojReasons For Hope In Commodity Prices
May 2, 2016
For many months now, the doomsayers have ruled the day in agriculture. Too much supply with too little demand would Read More
Eric SfiligojMissing The Family Ties In Agriculture
April 25, 2016
By its nature, the agriculture market is cyclical. Up and down cycles come and go with a regular pattern. For Read More
HerbicidesHerbicide Resistance In Waterhemp Continues To Grow
April 22, 2016
Twenty-five years ago, waterhemp was virtually unknown to Illinois farmers. Today, the broadleaf weed blankets corn and soybean fields across Read More
Latest News
Southern States Cooperative
Corn Field
Industry NewsTiger-Sul Names Veteran Account Manager To Lead Central…
May 23, 2016
With the continuing growth of the sulphur bentonite and precision crop nutrient industry, global agriculture firm H.J. Baker has announced that Read More
Bayer sign
Industry NewsReuters: Bayer Defies Critics With $62 Billion Monsanto…
May 23, 2016
German drugs and crop chemicals group Bayer has offered to buy U.S. seeds company Monsanto for $62 billion in cash, Read More
Eric SfiligojPity The Monsanto Haters
May 23, 2016
An old saying goes thus: “Be careful what you wish for. You just might get it.” Given current events, there Read More
Industry NewsCompass Minerals Hires Industry Veteran To Lead Plant N…
May 19, 2016
Compass Minerals has hired plant nutrition industry veteran Vatren Jurin to steer the company’s portfolio expansion into specialty liquid micronutrient Read More
ASMARK Retailers LIVE! Tour 2016 Group shot The Andersons
CropLife 100The Andersons Rejects Unsolicited Proposal From HC2
May 19, 2016
The Andersons, Inc. has announced that its Board of Directors has rejected two non-binding, highly conditional, unsolicited proposals from HC2 Read More
glyphosate
Crop InputsWHO: Glyphosate ‘Unlikely’ To Cause Cancer
May 16, 2016
Via Reuters.com reporter Kate Kelland: The weed-killing pesticide glyphosate, made by Monsanto and widely used in agriculture and by gardeners, Read More
dicamba, Roundup Ready 2 Xtend
Crop InputsASA: No Dicamba On Roundup Ready 2 Xtend In 2016
May 16, 2016
While Roundup Ready 2 Xtend (RR2X) are tolerant to dicamba and glyphosate herbicides, no dicamba herbicides will be approved for Read More
CPP, glyphosate, dicamba, atrazine,
Crop InputsReport: Congress Pressing EPA On Glyphosate Review Hand…
May 16, 2016
Via Reuters.com reporter P.J. Huffstutter: U.S. lawmakers have asked EPA to explain why it published – and then withdrew – Read More
Monsanto Luling Plant
Crop InputsReport: Bayer Eyeing Monsanto For Possible Mega-Merger
May 16, 2016
Bayer AG is exploring a potential bid for U.S. competitor Monsanto Co. in a deal that would create the world’s Read More
ManagementAsmark Institute Tour Observations
May 12, 2016
Special Guest CropLife Field Editor Matthew Grassi discusses his week-long visit with 45 ag retailers as part of the Asmark Read More
MicronutrientsCompass Minerals Expands Trial Work For Wolf Trax Innov…
May 12, 2016
Fertilizer manufacturer Compass Minerals continues to expand the evaluation program for its Wolf Trax micronutrient fertilizer products, according to a Read More
Young Corn Closeup
Industry NewsArysta Adds To Marketing Team
May 12, 2016
Arysta LifeScience North America recently announced the addition of David Davies to its marketing team. As marketing manager, Davies will Read More
Photo credit: The United Soybean Board/The Soybean Checkoff.
Crop InputsSyngenta Launches New Biological Seed Treatment
May 12, 2016
Syngenta has announced the launch of the EPIVIO brand family, a range of new biostimulants which address abiotic stresses through seed Read More
Crop Inputs2013 West Texas Tragedy Ruled A ‘Criminal ActR…
May 11, 2016
A 2013 fertilizer plant blast in West, TX, that killed 15 people and injured 160 others was caused by a Read More
Crop InputsLariat Partners Invests In Willowood USA
May 11, 2016
Lariat Partners, a Denver-based private equity firm, has made a significant investment in Willowood USA, a leading manufacturer of generic Read More
Anhydrous Ammonia tanks
LegislationARA: OSHA Announces PSM Formal Rulemaking Intentions
May 11, 2016
In separate communications earlier this week, the Occupational Safety and Health Administration (OSHA) announced plans to conduct formal rulemaking to Read More
The Andersons Fostoria
StewardshipThe Andersons Facilities In Fostoria And Gibsonburg, OH…
May 11, 2016
The 4R Nutrient Stewardship Certification Program has announced that The Andersons, Inc.’s facilities in Fostoria and Gibsonburg, OH, have been added to its Read More