Glyphosate-Resistant ‘Superweeds’ May Be Less Susceptible To Disease

Scientists searching for clues to understand how superweeds obtain resistance to the popular herbicide glyphosate may have been missing a critical piece of information, a Purdue University study shows.

Glyphosate, the active ingredient in the weed killer sold under the name RoundUp, is the most widely used herbicide in the United States, but some plants have grown resistant to it. This has caused growers to turn to additional herbicides. While the mechanisms that have led to resistance are not fully known, Bill Johnson, a professor of weed science; Steve Hallett, an associate professor of weed science; and Jessica Schafer, a graduate student in botany and plant pathology, believe that soil microbes may play a role.

Most laboratory tests done to understand glyphosate resistance are done in sterile soil, void of those microbes. Schafer said Purdue’s findings, published online early in the journal Weed Science, show that those microbes may play a significant role in how glyphosate affects plants.

“The soil you’re growing the plants in is important to the results,” Schafer said. “If we’re growing in a sterile media, we could get some false positive results because the plants are more tolerant to glyphosate in those conditions.”

Hallett and Schafer grew giant ragweed, horseweed and common lambsquarter in both sterile soil and field soil and subjected them to glyphosate. In each soil, strains of weeds both susceptible and resistant to glyphosate were tested.

Both versions of giant ragweed were damaged more from the glyphosate in field soil. The susceptible version of common lambsquarter was also more heavily damaged in field soil. Horseweed fared the same no matter which soil or strain – susceptible or resistant.

The results show that microbes can play an important role in the activity of glyphosate, presumably by invading the glyphosate-weakened plants. The results also suggest that glyphosate-resistant weeds may be more resistant to disease pressure as well.

“Soil microbes can be minor to major contributors to how glyphosate is able to affect plants,” Hallett said. “We may be selecting not only for glyphosate resistance, but inadvertently selecting for weeds that have disease resistance as well.”

A weed’s ability to withstand glyphosate was based on dry shoot and root weight after testing. The sterile soil used in the study came from field soil exposed to gamma radiation to kill microbes and bacteria. The irradiated soil was tested to ensure that its nutrients were not diminished.

Hallett, Johnson and Schafer said further studies would look at how fungi in the soil affect root development, both with and without glyphosate.

“Dirt is a living organism,” Johnson said. “It’s important to know how all the pieces interact.”

The research was conducted with internal funding from Purdue’s Department of Botany and Plant Pathology.

Topics:

Leave a Reply

Herbicides Stories

HerbicidesScouting Key To Next Season’s Soybean Herbicide Program
August 12, 2014
When growing soybeans, growers need to think ahead to stay one step ahead of weeds. That means examining weed threats and evaluating which herbicides work best. Read More
HerbicidesArysta Touts Burndown Herbicide For Brome Management In Wheat
June 4, 2014
Arysta LifeScience North America recommends PRE-PARE Burndown Herbicide for effective brome management in winter wheat. Read More
HerbicidesFall Herbicide Applications More Effectively Manage Resistant Italian Ryegrass
May 14, 2014
Field studies show that a fall application of certain herbicides before weed emergence, leads to more successful crop planting and weed control in spring. Read More
Waterhemp in soybean stubble
HerbicidesThe Weed Resistance Problem: A Matter Of Billions
April 1, 2014
Not only is the amount of money being spent to control these yield robbers high, but the toll it has taken on the human population is growing lager by the day. Read More

Top 100 Articles

CropLife 100CHS: Driving Momentum To Help Farmer-Owners Grow
December 11, 2014
CHS Inc., the nation’s leading farmer-owned cooperative and a global energy, grains and foods company, must capture new opportunities to Read More
CropLife 100BRANDT, Verdesian Ink Distribution Agreement
December 9, 2014
The agreement grants BRANDT the exclusive right to sell and market Verdesian’s patented Steric chemistry in the Turf and Ornamental and eastern U.S. ag markets under the BRANDT Reaction product line name. Read More
CropLife 100CropLife 100: The Colors Of Custom Application
December 5, 2014
Although many color spray rigs are in the yards of the nation’s top ag retailers, the majority of them still come in only a few shades. Read More
CropLife 100Pinnacle Invests In Meridian Agriculture Distribution
December 4, 2014
Meridian will provide retailers with supplier-branded products and numerous opportunities to differentiate themselves from their competitors. Read More
CropLife 100CropLife 100: Entering A New Seed Era
December 4, 2014
The seed category has been re-vitalized during the past few years, and more good news (and varieties) are headed the industry’s way in 2015. Read More
CropLife 100CropLife 100: The Depressed State Of Fertilizer
December 3, 2014
Following downright giddy growth earlier this decade, fertilizer sales have fallen back down to earth the past two years. Read More

Latest News

Crop InputsNufarm Fills Regulatory VP Position
December 18, 2014
Nufarm announced today that Rob Schwehr has been promoted to the position of Vice President of Innovation & Regulatory Affairs for Nufarm Americas. Read More
Seed/BiotechReport: China Approves Viptera Corn, U.S. Officials Awa…
December 17, 2014
Chinese authorities have informed some agriculture industry officials the government has approved U.S. imports of a type of genetically modified corn developed by Syngenta. Read More
FertilizerMonty’s Plant Food Brings In New Sales Rep
December 16, 2014
Monty's Plant Food Company has hired Warren Kearns as its newest Sales Representative for the South Carolina area. Read More
EquipmentHagie Wins 2014 CropLife IRON Product Of The Year Award
December 15, 2014
The self-propelled sprayer maker has a hit on its hands with the new STS Series model. Read More
Syngenta
Seed/BiotechSyngenta Sees China Approving Contentious GMO Corn Soon
December 15, 2014
Syngenta will make an announcement when it receives official documentation from China that Agrisure Viptera corn, known as MIR 162, has been cleared for import. Read More
Crop InputsVerdesian Life Sciences Names Vice President Of Communi…
December 15, 2014
Amy Bugg will oversee the execution of all promotional strategies for the corporate brand and the complete product portfolio. Read More
StewardshipFarmers, Retailers Attend 4R Certification 4U Workshop
December 15, 2014
More than 160 farmers and ag retailer attended the “4R Certification 4U” workshop December 12 to learn more about the 4Rs of nutrient stewardship, water quality research in the area and cost-sharing opportunities. Read More
Matt Hopkins10 Best New Agriculture Apps For 2015
December 15, 2014
These new agriculture apps are certain to help ag professionals do their jobs more efficiently in 2015 and beyond. Read More
ManagementARA Learnings, Retail Buying Intentions: Welcome To Cro…
December 12, 2014
This informal video program puts news and events effecting retailers into context, and features Editors Paul Schrimpf and Eric Sfiligoj. Read More
Seed/BiotechMonsanto Herbicide-Tolerant Technology Closer To Commer…
December 12, 2014
The final EIS moves Monsanto one step closer to the introduction of Bollgard II XtendFlex cotton and Roundup Ready 2 Xtend soybeans, paving the way to provide access to dicamba-tolerant soybeans and cotton. Read More
Seed/BiotechUSDA Issues Final Environmental Impact Statement On Her…
December 12, 2014
The USDA Animal and Plant Health Inspection Service (APHIS) is issuing a final environmental impact statement on varieties of cotton and soybeans that have been genetically engineered for resistance to several herbicides, including the one known as dicamba. Read More
CropLife 100CHS: Driving Momentum To Help Farmer-Owners Grow
December 11, 2014
CHS Inc., the nation’s leading farmer-owned cooperative and a global energy, grains and foods company, must capture new opportunities to Read More
LegislationARA Applauds CFATS Passage Prior To Holiday Adjournment
December 11, 2014
The streamlined bill provides a four-year authorization of the CFATS program and guidance to DHS on key issues of chemical facility security Read More
Seed/BiotechBayer CropScience’s ILeVO Approved By EPA
December 11, 2014
EPA has approved ILeVO, the only seed treatment that protects the root system against infections caused by the Sudden Death Syndrome fungus and has activity against dangerous nematodes. Read More
Biologicals in Emerging Markets Map.
Crop InputsBiocontrols Could Quadruple By 2025; Will Regulators Pl…
December 11, 2014
The European experience with GMOs offers caution — and a promise — for biologicals. Read More
Crop InputsBASF Donates $75,000 To Feeding America
December 10, 2014
The donation will support Feeding America’s National Produce Program, an initiative that helps with planning, transportation and logistics to ensure fresh produce deliveries to the 200 member food banks around the country. Read More
InsecticidesHow To Avoid Aphid Infestation In Winter Wheat
December 10, 2014
The best strategy for managing aphid infestations in winter wheat — and the potential yellow dwarf diseases that they transmit — is prevention, according to a South Dakota State University Plant Pathology field specialist. Read More
LegislationDufault Installed As New ARA Chair
December 10, 2014
Dave Dufault, Vice President and General Manager of J.R. Simplot Company's Retail Business, was installed as the 2015 Chairman of the Board for ARA on December 4. Read More