Although Pennsylvania has a more diversified cropping mix than Southern states, it nonetheless is beginning to see glysphosate-resistant Palmer amaranth creep into fields.
In the South where growers have relied heavily on Roundup Ready crops, they now spend up to $100 per acre to fight the resistant weed, according to a news release.
Reports of glyphosate-resistant Palmer pigweed are trickling in from Pennsylvania's producers as well as those in Delaware and Maryland.
A second resistant species, waterhemp, also is beginning to creep into Pennsylvania.
Despite the reports, Penn State Extension weed scientist Dwight Lingenfelter says glyphosate is still an important burn-down herbicide.
To minimize the chance of resistance developing,Lingenfelter recommends using tankmixes or pre-mixes that contain multiple modes of action.
"The majority of the resistance problem in these other regions is they were relying on a single mode of action—that being glyphosate," Lingenfelter said in the release.