Location: Dairy Forage ResearchTitle: Field testing Northern U.S. adapted 2,4-D resistant red clover (Trifolium pratense L.)
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/14/2016
Publication Date: 7/14/2016
Citation: Riday, H. 2016. Field testing Northern U.S. adapted 2,4-D resistant red clover (Trifolium pratense L.). Crop Science. 56:2314-2321.
Interpretive Summary: Red clover varieties that are resistant to 2,4-D herbicide would offer producers more weed control options, particularly in mixed grass/red clover pastures. A red clover variety that is adapted to the northern United States, and is tolerant of the 2,4-D herbicide, has been developed. This study examined the performance of this material under field conditions after applying recommended rates of 2,4-D to the red clover plants. Control plants (not resistant to 2, 4-d) were essentially 100% killed under these conditions, while no significant death was observed among the 2,4-D resistant red clover plants. There was, however, a noticeable decline in plant biomass yields at 71% of potential. This study confirms the feasibility of developing herbicide resistant forage crops using conventional breeding. However, further breeding work should be done to eliminate the 71% decline in biomass yield caused by 2,4-D application.
Technical Abstract: 2,4-Dichlorophenoxyacetic acid (2,4-D) resistant red clover (Trifolium pratense L.) varieties would offer producers more weed control options, particularly in mixed grass/red clover pastures. In the 1980s, work was initiated in Florida to select for 2,4-D tolerant red clover (Taylor, 1989). This Florida germplasm, however, was not adapted to cool humid regions in the Northern United States. A greenhouse selection program was initiated to develop 2,4-D resistant germplasm more adapted to the Northern United States. A field study was conducted to determine field resistance of this germplasm (WI-2,4D12) to a standard 2,4-D application rate. While the standard non-2,4-D resistant red clover had essentially 100% kill following 2,4-D application, the WI-2,4D12 had no significant decline in persistence following herbicide application. However, some plant vigor (i.e., proxy for biomass) loss was noted with the WI-2,4D12 germplasm. This study confirms the feasibility of developing herbicide resistant forage crops using conventional breeding. Future breeding work should focus on further improving red clover 2,4-D resistance to eliminate biomass yield loss due to herbicide plant injury. Ascertaining the major genetic bases of this resistance would facilitate more rapid movement of the resistance into other elite cultivated red clover germplasm.