Acetolactate syntahse (ALS) resistant Amaranthus palmeri
Wise, Aaron Micahel
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Studies were conducted from 2005 to 2007 to establish the geographical, distribution extent, dose response, and heritability for acetolactate synthase (ALS)-resistance in Georgia Palmer amaranth. Sites were randomly selected from across the state’s agronomic production region from suspected ALS resistant populations. From these populations, entire female thyrses were clipped from the plant, collected from as many plants as possible from 61 locations. Samples were stored at 4 C for 45 days until seed processing. Tests were conducted in a greenhouse. Plants were screened for resistance at the 4 to 5 leaf growth stage. Seedlings were screened for susceptibility after treatments of imazapic at 70 and 700 g ai/ha for each location. Plants were visually rated for injury using a scale of 0 (plant death) to 100% (no injury) at 14 and 21 d after treatment. ALS-resistance in Palmer amaranth populations ranged from 45-97%. Populations tested were not resistant to glyphosate.