Dig Those Corn Rootworms

It’s a dirty job, but someone has to do it. In fact, entomologists are encouraging more growers and their retailers to dig corn roots this coming summer to look for signs of corn rootworm feeding.

“Digging roots when it’s hot outside and corn is pollinating usually isn’t something a person would choose to do,” says Kevin Steffey, entomologist with the University of Illinois. But with the increasing spread of western and northern corn rootworms to rotated corn, Steffey says it’s important to monitor what’s happening below ground.
“Corn rootworm is not a problem in every corn field in every year,” says Steffey. “But between extended diapause in northern corn rootworms and the variant western corn rootworm, pressure in first-year corn is spreading.”

That’s in addition to continuous corn rotations, where rootworm pressure is common in most areas of the Corn Belt. “Corn after corn is the crop sequence that the corn rootworm has made its living on for many years,” reminds Jon Tollefson, entomologist with Iowa State University.

Whether growing first-year or continuous corn, digging and rating roots isn’t just a good way to monitor root damage, “it’s the only way,” says Iowa State University entomologist Marlin Rice.

Lodging is probably the most obvious indicator of a rootworm problem, but it’s not a reliable one. “Lodging can have nothing to do with rootworm control,” says Rice. “You can have a strong wind take down your corn, especially in a wet field, and it won’t have anything to do with rootworm feeding.”

You can’t go by root ball size or stalk strength either, says Larry Bledsoe, entomologist with Purdue University. “Those are genetic factors that are largely determined by your hybrid,” he explains.

“What you’re looking for is signs of root feeding, and the only way to do that is to dig up roots and look at them — especially during mid to late July after most of the injury has occurred,” says Rice.

“If you suspect rootworm pressure or want to compare control methods, don’t wait until harvest to look at your roots,” advises Von Kaster, entomologist with Syngenta Seeds “It’s a hassle, but an in-season root dig will really give you the clearest picture of what’s happening in your fields.”

To help growers rate rootworm damage, Iowa State University has developed an interactive web site that illustrates degrees of root feeding damage based on a 0 to 3 scale. Visit www.ent.iastate.edu/pest/rootworm/ for information.
“There’s no magic number on the scale that definitively indicates when we reach the point of yield loss,” says Kaster. Soil moisture, root regeneration — even wind — can affect the extent of yield loss from root feeding.

When evaluating rootworm control methods, Kaster advises looking at root ratings from multiple sites. “That will give you a much broader view of insect control over a range of weather, soil and cultural conditions,” he explains. “For example, root ratings from Syngenta and university trials representing 57 site years in 2004- 07 demonstrate (Syngenta Seeds’) Agrisure RW is very consistent across locations, with an average root rating of 0.22.”

Entomologists agree that it’s important to look at a variety of results when evaluating any corn rootworm control method. Likewise, it’s important to monitor what’s happening below ground in your grower’s fields. Take a look at the ISU root ratings Web site this winter and make sure you’re out in those fields this summer with a strong shovel and a cold water bottle.
 

Leave a Reply

Insecticides Stories

Crop InputsCreate a ‘No-Mite Zone’ Around Your Fields
July 13, 2017
Explosive. That’s one way to describe the speed at which mite infestations in crops can develop under the right conditions. Read More
Redbanded-stinkbug-on-soybean-Photo-credit-Thomas-County-Ag
Crop InputsExperts: Mild Winter, Early Planting Will Increase Soybean Insect Threat
June 12, 2017
Higher than average temperatures this past winter affected much of the nation, especially the South and Midwest. The National Centers Read More
Soybean field
FungicidesAMVAC Closes Deal for Three Product Line Acquisitions from Adama
June 6, 2017
AMVAC Chemical Corp. announced the closing of its acquisition of three new products to its portfolio – abamectin insecticide, chlorothalonil Read More
Young corn plants in soil
Crop InputsFortenza Insecticide Seed Treatment Receives EPA Registration
May 25, 2017
Fortenza seed treatment insecticide from Syngenta has received registration approval from the U.S. EPA for use on corn and cotton Read More
Trending Articles
Tim Hassinger Dow AgroSciences President and CEO
Crop InputsDow’s Tim Hassinger Named President, CEO of Lindsay Corp.
July 24, 2017
Lindsay Corp. has  announced the appointment of Timothy Hassinger as president and CEO and a member of its board of Read More
Stewardship‘Gonna Fly Now’ with Environmental Respect
July 20, 2017
One of the most memorable moments in movie history occurred in the Academy Award-winning 1976 film “Rocky.” Haven gotten his Read More
StewardshipEnvironmental Respect 2017 Kicks Off Enjoying an American Pastime
July 18, 2017
Following months of planning and scheduling, the 2017 Environmental Respect Awards (ERA) celebration kicked off in fine fashion as more Read More
Soybean Closeup
Crop InputsMissouri Lifts Dicamba Ban, Issues Stricter Application Parameters
July 14, 2017
The Missouri Department of Agriculture has lifted its barely week-old ban on new dicamba technologies, which have been at the Read More
Crop InputsMonsanto Responds to Arkansas, Missouri Dicamba Bans
July 10, 2017
Monsanto, provider of the dicamba-tolerant Roundup Ready Xtend crop system for soybeans and cotton, issued the following statement on Friday, Read More
Retail FacilitiesPCS-Hammond Meets Fertilizer Storage Needs with New Dome Facility
July 8, 2017
The new barrel dome facility at the PCS-Hammond Regional Distribution Center in Hammond, IN, can hold more than 100,000 tons Read More
Latest News
EquipmentAGCO to Acquire Precision Planting
July 26, 2017
AGCO and The Climate Corp. announced today that a definitive agreement has been signed for AGCO to acquire the Precision Read More
CPS-Norwood-and-Dupont-reps
Eric SfiligojA Message to Ag Retailers: Do Tell Your Good Stories
July 26, 2017
As the daughter of a peanut farmer, Krysta Harden, Chief Sustainability Officer for DuPont Crop Protection, understands the importance ag Read More
Iowa-State-Seed-Science-Center
Seed/BiotechIowa State Celebrates 10 Years of Online Seed Education
July 26, 2017
This year, Iowa State University is celebrating 10 years of service to the seed industry through its online Graduate Program Read More
Corn seed treatment
Seed/Biotech5 Steps for Stewardship of Treated Seed
July 26, 2017
With planting season just around the corner, the American Seed Trade Association (ASTA) reminds farmers to follow five basic steps Read More
Darin Lickfeldt Verdesian In Field
Crop InputsVerdesian: Sustainability Goes Hand in Hand with Profit…
July 25, 2017
Sustainability is a hot topic in agriculture these days. And while measuring sustainability and its on-farm impact can seem difficult Read More
Crop InputsBASF: In Arkansas Drift Cases, Buffer Zones Mostly Not …
July 24, 2017
BASF on Thursday addressed questions about spreading dicamba drift issues on a media briefing call. In Arkansas – which is Read More
Tim Hassinger Dow AgroSciences President and CEO
Crop InputsDow’s Tim Hassinger Named President, CEO of Linds…
July 24, 2017
Lindsay Corp. has  announced the appointment of Timothy Hassinger as president and CEO and a member of its board of Read More
Eric SfiligojThe 2017 Ambassadors of Respect Come from Around the Gl…
July 24, 2017
After a week of fun, enjoying food, sights, and company information, DuPont Crop Protection representatives and their Environmental Respect guests Read More
ManagementCropLife Retail Week: Dicamba Update and InfoAg Preview
July 21, 2017
Editors Eric Sfiligoj and Paul Schrimpf discuss reports from the field and comments from Monsanto about dicamba drift this season, Read More
Stewardship‘Gonna Fly Now’ with Environmental Respect
July 20, 2017
One of the most memorable moments in movie history occurred in the Academy Award-winning 1976 film “Rocky.” Haven gotten his Read More
StewardshipEnvironmental Respect: Grand Grounds, Posters Parade
July 19, 2017
To celebrate their accomplishments in the area of environmental stewardship, award recipients at the 2017 Environmental Respect week spent much Read More
StewardshipHarden’s Message to ERA Winners: Do Tell Your Good Stor…
July 19, 2017
As the daughter of a peanut farmer, Krysta Harden, Chief Sustainability Officer for DuPont Crop Protection, understands the importance the Read More
StewardshipFarming Smarter Hinges on 4R Best Management Practices
July 18, 2017
Preserving water quality while feeding another 2 billion people by 2050 is the challenge facing North America’s farmers and its Read More
StewardshipEnvironmental Respect 2017 Kicks Off Enjoying an Americ…
July 18, 2017
Following months of planning and scheduling, the 2017 Environmental Respect Awards (ERA) celebration kicked off in fine fashion as more Read More
Soybean Field Sunset
OpinionPicking Partners in the Crop Protection Market
July 17, 2017
Agriculture is a market awash in highs, lows, and everything in between. This is certainly true in the world of Read More
TMX-2050-In-Cab-Display-Launch-Run-Screen
EquipmentGPS Auto Steer: Innovating in a Mature Market
July 17, 2017
In the world of Big IRON, GPS auto steer has closely mirrored the evolutionary path of consumer GPS Navigation systems Read More
MFA-Centralia-MO
Eric SfiligojThe Resilience of Ag Retailers
July 17, 2017
After covering the ag retail market for 17 years, I think one of the most impressive character traits I’ve seen Read More
SERA-meeting
Stewardship4R Event Explores How to Minimize Phosphorus Losses
July 17, 2017
This year the Southern Extension and Research Activity (SERA) – 17; will be meeting in Oregon, OH, from August 14-17. Read More