Glyphosate-resistant weeds also may be disease resistant

07/18/2012 07:06:00 AM
Vicky Boyd

So-called "superweeds" resistant to the herbicide glyphosate also may be more resistant to disease pressures.

Those are the findings of research conducted by weed science professor Bill Johnson, associate weed science professor Steve Hallett and graduate student Jessica Schafer, all of Purdue University in West Lafayette, Ind., according to a news release.

The group subjected giant ragweed, horseweed and common lambsquarter to glyphosate treatments.

Part were conducted in a laboratory, using sterile soil.

The other half was conducted in the field under field conditions.

In each soil type, they tested both strains known to be susceptible to the herbicide and strains known to be resistant.

What they found were both types of giant ragweed were more heavily damaged by glyphosate in the field.

The susceptible strain of lambsquarter also was more heavily damaged in the field, and horseweed fared the same in the field, regardless of the strain.

What the group theorizes is microbes may plan a role in glyphosate activity, probably by invading herbicide-weakened plants.

The results also suggest that glyphosate-resistant plants also may be more resistant to diseases.

"We may be selecting not only for glyphosate resistance, but inadvertently selecting for weeds that have disease resistance as well," Hallett said in the release.

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John R. French    
Marietta, Georgia  |  November, 22, 2013 at 09:29 PM

Next logical research topic: Are glyphosate resistant crops more disease resistant than non-GMO varieties? If so, then the genomics of glyphosate resistance should be investigated as to how it conditions disease resistance. Is phytoalexin inducement involved? If so, what are the potential utilities of the resistance mechanism for maximizing efficiency not only of herbicide deployment but of measures taken to prevent agricultural & horticultural diseases? These are fertile fields for potentially valuable research.

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