Publication Type: | Journal Article |
Year of Publication: | 2009 |
Authors: | Puri, A, Haller, WT, Netherland, MD |
Journal: | Weed Science |
Volume: | 57 |
Issue: | 5 |
Date Published: | 2009 |
ISBN Number: | 00431745 |
Keywords: | Hydrilla |
Abstract: | The development of fluridone resistance by hydrilla has significantly impacted hydrilla management, and research is ongoing to develop alternate herbicides for effective hydrilla control. We determined the potential cross-resistance in fluridone-resistant hydrilla to other bleaching herbicides norflurazon, mesotrione, and topramezone-methyl. Phytoene, βcarotene, and chlorophyll contents as a function of hydrilla biotype and herbicide treatment were evaluated. Hydrilla shoot tips were collected from fluridone-susceptible (S) and -resistant (R) biotypes and exposed to 5, 25, 50, 75, and 100 μg L⁻¹ of herbicide. The susceptible biotype showed an increase in phytoene and a decrease in β-carotene and chlorophyll contents when treated with 5 µg L⁻¹ fluridone, whereas higher doses of fluridone were required to affect these pigments in the resistant biotype. There was no difference in response by S and R biotypes to mesotrione and topramezone-methyl, with both biotypes showing significant affects on pigment contents at 5 µg L⁻¹ Higher doses of norflurazon were required to affect these pigments in the R compared to the S biotype. The S biotype had EC₅₀ values of 11.7, 12.2, and 4.7 µg L⁻¹ whereas the R biotype had EC₅₀ values of 56.6, 41.1, and 41.7 µg L⁻ fluridone for phytoene, β-carotene, and chlorophyll contents, respectively. There was no difference in EC₄₀ for phytoene, β-carotene, and chlorophyll values between the hydrilla bio types for mesotrione and topramezone-methyl herbicides. In fluridone-susceptible and -resistant hydrilla biotypes, EC₅₀ values for phytoene, β-carotene, and chlorophyll were 12.4 to 11.8, 10.2 to 13.2, and 3.1, to 4.6 µg L⁻¹ mesotrione and 12.6 to 13.5, 13.3 to 11.9, and 4.6 to 5.7 µg L⁻¹ topramezone-methyl, respectively. For norflurazon, S and R biotypes had EC₅₀ values of 33.1, 45.4, and 40.6 µg L⁻¹ and 84.6, 81.0, and 92.7 µg L⁻¹ for phytoene, β-carotene, and chlorophyll, respectively. These studies confirmed negative cross-resistance of fluridone-resistant hydrilla to mesotrione and topramezone-methyl and a positive cross-resistance to norflurazon. |
URL: | http://www.jstor.org/stable/40586860 |
Short Title: | Weed Science |
Cross-Resistance in Fluridone-Resistant Hydrilla to Other Bleaching Herbicides
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