| Description: |
There are currently nine reported herbicide-resistant weed species in Nebraska, six of which are resistant to glyphosate. Overall distribution and frequency of these resistant species is unknown. The objectives of this research were to understand the frequency and distribution of glyphosate-resistant weeds in Nebraska. Common and problematic weeds of Nebraska were arbitrarily collected from fields in 77 counties during the fall of 2013-2015. From our statewide collection, five species including: horseweed (Conyza canadensis (L.) Cronq.), kochia (Kochia scoparia (L.) Schrad.), Russian-thistle (Salsola tragus L.), giant ragweed (Ambrosia trifida L.), and common lambsquarters (Chenopodium album L.) were selected and subjected to a dose response study at the Pesticide Application Technology Laboratory in North Platte, NE. With these collected populations, a dose response screening was conducted for their resistance to glyphosate, if present, and determine the statewide distribution of glyphosate-resistance. Resistance was again confirmed in horseweed, giant ragweed, and kochia, with resistant populations being found throughout the eastern, north eastern, and south western portions of the state. No glyphosate resistance was observed among collected populations of common lambsquarters and Russian thistle. Adviser: Greg R. Kruger |