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ARS Home » Southeast Area » Tifton, Georgia » Crop Protection and Management Research » Research » Publications at this Location » Publication #250045
Title: Cross and Multiple Herbicide Resistance in Palmer amaranth (Amaranthus palmeri)

Author
item GREY, T.L. - University Of Georgia
item SOSNOSKIE, L.M. - University Of Georgia
item CULPEPPER, A.S. - University Of Georgia
item PROSTKO, E.P. - University Of Georgia
item VENCILL, W.K. - University Of Georgia
item Webster, Theodore

Submitted to: Panamerican Conference
Publication Type: Abstract Only
Publication Acceptance Date: 2/1/2011
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Resistance of Palmer amaranth (PA) to ALS inhibitor herbicides was discovered in Georgia in 2000 and resistance to glyphosate was in 2005. A study was conducted to evaluate two different families of ALS herbicides, imazapic (imidazolinone) and diclosulam (sulfonanilides) for absorption and mobility in the plant using 14C techniques. In order to evaluate multiple resistance, a PA accession was evaluated with pyrithiobac (ALS herbicide) and glyphosate. No differences were observed for the susceptible and resistant biotypes for the uptake of 14C-imazapic or 14C-diclosulam. However, imazapic exhibited greater translocation out of the treated leaf. There was no difference between translocation of 14C-diclosulam or 14C-imazapic for the ALS-resistant biotype, indicating similar herbicide absorption. For the multiple resistance evaluation, visual control rating I50 values for glyphosate-resistant and glyphosate/ALS resistant biotypes were at least 12-times greater than the I50 value for susceptible biotype. ALS-resistant and glyphosate/ALS resistant biotypes were at least 150-times greater than the I50 values for the glyphosate and ALS susceptible biotype when treated with pyrithiobac. Similar results occurred with the fresh biomass assessment. These data indicate that PA multiple herbicide resistance, and cross resistance to glyphosate and pyrithiobac does occur in Georgia.