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
InsecticidesHow To Scout For Corn Earworms In Corn
July 28, 2014
In her weekly report, University of Missouri Agronomy Specialist Jill Scheidt discusses what to look for when scouting for corn earworm. Read More
InsecticidesEPA Grants Besiege Insecticide Additional Approvals
June 18, 2014
EPA has granted additional registration approvals for the use of Syngenta's Besiege insecticide on sorghum, cereal grains and peanuts. Read More
InsecticidesPrevathon Insect Control Approved For Cereal Crops
January 13, 2014
DuPont's Prevathon insect control powered by Rynaxypyr has received U.S. EPA registration for use on cereal crops, including wheat, most other small grains and sorghum. Read More
InsecticidesInsecticides 2014: Insect Pressure, Solutions On The Rise
January 2, 2014
Bt resistance, weather concerns and myriad other issues have led to an increase in both traditional pest pressures as well as new pests. Read More
Top 100 Articles
Growmark Group
CropLife 100GROWMARK In 2015: Back, To The Future
March 2, 2015
The nation’s third largest ag retail organization is simultaneously moving forward while remembering its past. Read More
CropLife 100Pinnacle Expands Sanders Brand In The South
February 27, 2015
Pinnacle has acquired Hopkins Seed and Chemical in Qulin, MO, which expands the company's Sanders brand to nine Southern states. Read More
CropLife 100Pinnacle Launches New Providence Agriculture Location In Indiana
February 27, 2015
Pinnacle Agriculture Holdings — ranked No. 6 on the CropLife 100 — has established a new retail location in New Castle, IN, which will operate as part of Pinnacle's Providence Agriculture brand. Read More
CropLife 100Cooperative CHS Returns $518 Million To Owners
February 23, 2015
The 2015 cash return to owners is based on CHS net income of $1.1 billion, the company's second highest on record. Read More
corn field
CropLife 100The Andersons’ Humic DG Now Available In Canada
February 13, 2015
The Andersons, Inc. Turf & Specialty Group has announced its Humic DG product is now available to customers in the Canadian turf, agriculture and horticulture markets. Read More
Farmer on tablet
CropLife 100Southern States Co-op: An Inside Look At Our Aerial Imagery Program
February 8, 2015
Now is as good a time as any to explore the basics of what a retail aerial imagery program looks like today. Read More
Latest News
Eric SfiligojCommodity Classic 2015: Playing The Waiting Game
March 2, 2015
There was plenty of future-talk at this year’s event as companies (and growers) are largely in a holding pattern of sorts. Read More
Industry NewsHighway Equipment Appoints New Director Of Business Dev…
March 2, 2015
Cory Venable, who joined Highway Equipment Company (HECO) in 2013 as OEM Account Manager, has been promoted to Director of Business Development. Read More
Prairieland FS employees
Eric SfiligojWorkforce Worries
March 2, 2015
Finding good employees almost always ranks as the No. 1 or No. 2 problem for ag retailers in our annual CropLife 100 survey. Read More
Growmark Group
CropLife 100GROWMARK In 2015: Back, To The Future
March 2, 2015
The nation’s third largest ag retail organization is simultaneously moving forward while remembering its past. Read More
CropLife 100Pinnacle Expands Sanders Brand In The South
February 27, 2015
Pinnacle has acquired Hopkins Seed and Chemical in Qulin, MO, which expands the company's Sanders brand to nine Southern states. Read More
CropLife 100Pinnacle Launches New Providence Agriculture Location I…
February 27, 2015
Pinnacle Agriculture Holdings — ranked No. 6 on the CropLife 100 — has established a new retail location in New Castle, IN, which will operate as part of Pinnacle's Providence Agriculture brand. Read More
2,4-D Celebrates 70 Years; GROWMARK Uses Super Bowl Ad To Share Positive Message
Management2,4-D Celebrates 70 Years; GROWMARK Uses Super Bowl Ad …
February 27, 2015
Jim Gray, executive director of the 2,4-D Research Task Force, lays out planned activities to mark the chemistry’s 70th anniversary. Read More
HerbicidesUniversity Of Arkansas Flag The Technology Program Adds…
February 27, 2015
Started in 2010, the Flag the Technology program provides a visual reference for applicators to distinguish between fields planted with different herbicide-tolerant trait technologies. Read More
Luckey Farmers, Inc.’s Berkey Farm Center
Industry NewsLuckey Farmers’ Berkey Branch Certified In 4R Nut…
February 26, 2015
The 4R Nutrient Stewardship Certification Program has announced Luckey Farmers Inc.’s Berkey Farm Center in northwest Ohio has been added to its growing list of nutrient service providers to achieve certified status. Read More
Crop InputsWinField Unveiling NutriVision Technology, Ascend Dry F…
February 24, 2015
New for 2015 are NutriVision Technology, a unique tool for monitoring in-season plant nutrient availability, and Ascend WSG plant growth regulator, a new dry formulation of Ascend plant growth regulator. Read More
FertilizerNew Formulation Of NutriSphere-N Protects High Volume U…
February 24, 2015
Verdesian Life Sciences is launching NutriSphere-N HVTM, a new polymer formulation of the proven NutriSphere-N Nitrogen Fertilizer Manager that protects high-volume applications of UAN. Read More
EquipmentIowa Ag Secretary Northey Names Hagie Water Quality Lea…
February 24, 2015
Iowa Secretary of Agriculture Bill Northey has named Hagie Mfg. as a recipient of the Secretary’s Water Quality Initiative (WQI) Leader Award. Read More
FungicidesEvito Fungicide Gives Canadian Wheat Growers New Diseas…
February 24, 2015
EVITO fungicide from Arysta LifeScience North America gives Canadian wheat and barley growers a new option for disease control. Read More
Eric SfiligojThe Commodity Classic Turns 20
February 23, 2015
Two decades in, this annual gathering of all things agriculture has become a must-see event. Read More
CropLife 100Cooperative CHS Returns $518 Million To Owners
February 23, 2015
The 2015 cash return to owners is based on CHS net income of $1.1 billion, the company's second highest on record. Read More
CropLife Retail Week: On The Road Edition
ManagementCropLife Retail Week: On The Road Edition
February 20, 2015
Editors Paul Schrimpf and Eric Sfiligoj discuss their recent trips to the National Farm Machinery Show in Louisville and the Read More
Crop InputsLand O’Lakes Acquires FLM+ Assets
February 19, 2015
FLM+ will become a wholly owned subsidiary of Land O'Lakes, Inc., and the company will retain its employee base after closing of the deal, which is scheduled for the second quarter of the year. Read More
Seed/BiotechUnited Suppliers, Stine Seed Form Marketing Alliance
February 19, 2015
The new alliance will greatly expand sales opportunities for Stine Seed with the United Supplier Seed Link Owners. Read More