|Mcgrath, J mitchell - Mitch|
Submitted to: Journal of Sugarbeet Research
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/20/2005
Publication Date: 3/2/2006
Citation: Dale, T.M., McGrath, J.M., Renner, K.A. 2006. Response of sugarbeet (Beta vulgaris) varieties and populations to postemergence herbicides. Journal of Sugarbeet Research. p.119-126. Interpretive Summary: Sugar beet yield and sugar content are seriously affected by weed competition, and herbicides are used extensively to control weed populations in the field until the sugar beet canopy is large enough to shade any newly emerging weeds. Sugar beet varieties differ in their tolerance to herbicides but it is not known how prevalent this tolerance is, and if it is genetically controlled. Experiments were conducted with commercial varieties and experimental hybrids to evaluate the variety component of herbicide tolerance. Results showed all varieties suffered growth setbacks due to herbicide application, and some were affected more than others. A genetic component of herbicide tolerance was suggested by looking at the response of different male sterile seed parents pollinated with the same pollen donor. These results demonstrate a genetic component of herbicide tolerance in beets, and this information will be useful for breeding and selecting improved sugar beet varieties that recover from herbicide injury faster than existing varieties.
Technical Abstract: Injury from herbicides may result in reduced sugarbeet yield or sugar content. Previous research has shown a differential response of sugarbeet varieties to herbicides. We evaluated the growth response of fourteen sugarbeet varieties and four USDA sugarbeet populations to postemergence applications of the micro-rate of desmedipham plus phenmedipham (1:1 ratio) at 0.09 kg ai/ha plus triflusulfuron at 0.004 kg ai/ha plus clopyralid at 0.023 kg ae/ha plus methylated seed oil at 1.5% v/v. Sugarbeets were sprayed three times at weekly intervals beginning at the cotyledon growth stage. Sugarbeet varieties varied in their response to micro-rate herbicide applications. The leaf area, fresh weight and dry weight of Hilleshog E-17 and ACH 555, two diploid varieties, were not reduced by micro-rate applications, while the leaf area of Beta 5400 and Beta 5736, two triploid varieties, was reduced by 24 and 35%, respectively, compared to their respective untreated controls. In the second experiment, the leaf area and fresh and dry weight of Spartan and E-17 were not reduced by postemergence micro-rate applications in the growth chamber or field, compared to their respective controls. Hilleshog E-38, ACH 185, and Beta 5736 had significant reductions in leaf area and dry weight in the growth chamber and field, while RH-5 had significant reductions in the growth chamber only, with tolerance not segregating by ploidy level. The USDA population WC 93404 was the most tolerant to micro-rate applications, with a 20% reduction in leaf area and 16% reduction in field dry weight, compared to reductions of 28% and 48% in leaf area and dry weight, respectively, of WC 93407 and WC 93409, suggesting a possible genetic component to herbicide tolerance.