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ARS Home » Southeast Area » Fort Lauderdale, Florida » Invasive Plant Research Laboratory » Research » Publications at this Location » Publication #319464
Title: Palmer Amaranth Identification and Documentation of Herbicide Resistance in Argentina

Author
item BERGER, SARAH - University Of Florida
item Madeira, Paul
item FERRELL, JASON - University Of Florida
item GETTYS, LYNN - University Of Florida
item MORICHETTI, S - Universidad Nacional De Cordoba
item CANTERO, J. - Universidad Nacional De Cordoba
item NUNEZ, C. - Universidad Nacional De Cordoba

Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 11/5/2015
Publication Date: 6/1/2016
Citation: Berger, S., Madeira, P.T., Ferrell, J., Gettys, L., Morichetti, S., Cantero, J.J., Nunez, C. 2016. Palmer Amaranth Identification and Documentation of Herbicide Resistance in Argentina. Weed Science Society of America Meeting Abstracts. 64(2):312-320. https://doi.org/10.1614/WS-D-15-00125.1.
DOI: https://doi.org/10.1614/WS-D-15-00125.1

Interpretive Summary: Palmer amaranth (Amaranthuspalmeri)is a weed which has created problems for many crops in the United States, especially as it has acquired resistance to many herbicides. This weed species is now suspected in Argentina. This study used DNA technology to confirm that several populations studied are palmer amaranth, others are the native mucronateamaranth (Amaranthusquitensis) and that the suspected hybridization has not occured in these samples. Additionally, these same plant populations were screened for herbicide resistance to several ALS-inhibiting herbicides (imazapic, nicosulfuron, and diclosulam). All Palmer amaranth populations from Argentina tested are resistant to at least one ALS-inhibiting herbicide. The populations were subjected to further testing to identify the mutation responsible for the observed ALS resistance. All mucronate amaranth populations exhibited a mutation previously documented to confer ALS resistance. No known resistance-conferring mutations were found in Palmer amaranth despite high levels of resistance which may be conferred by other mechanisms.

Technical Abstract: Palmer amaranth (Amaranthuspalmeri S. Wats.) has greatly disrupted agricultural practices in the US with its rapid growth and rapid evolution of herbicide resistance. This weed species is now suspected in Argentina. To document whether the suspected plant populations are indeed Palmer amaranth, molecular comparisons to known standards were conducted. Additionally, these same plant populations were screened for possible herbicide resistance to several ALS-inhibiting herbicides. Sequencing data confirmed that suspected populations (A2, A3, A4) were indeed Palmer amaranth. Another population (A1) was tested to determine whether hybridization had occurred between Palmer amaranth and mucronate amaranth (Amaranthus quitensis), the native amaranth species of the region. Tests confirmed that no hybridization had occurred and that A1 was simply a unique phenotype of mucronate amaranth. Each population was screened for resistance to imazapic, nicosulfuron, and diclosulam. All Palmer amaranth populations from Argentina were shown to be resistant to at least one ALS-inhibiting herbicide. The populations were then subjected to further testing to identify the mutation responsible for the observed ALS resistance. All mucronate amaranth populations exhibited a mutation previously documented to confer ALS resistance. No known resistance-conferring mutations were found in Palmer amaranth.