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| Publication Type:
| Report |
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| Content Type: | Abstract or Summary only |
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| Author(s): | Burgos, N. R.;
Talbert, R. E. |
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| Author Affiliation: | Department of Crop, Soil, and Environmental Sciences, University of Arkansas, Fayetteville, Arkansas |
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| Title: | How do we test for herbicide resistance? |
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| Section: | Education and regulatory aspects of weed management
Other records with the "Education and regulatory aspects of weed management" Section
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| Meeting Info.: | 55th Annual Meeting, Atlanta, GA: January 28-30, 2002 |
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| Source: | Southern Weed Science Society Proceedings. Vol. 55, 2002, p. 130-131. |
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| Publishing Information: | Champaign, IL: Southern Weed Science Society. |
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| # of Pages: | 2 |
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| Abstract/Contents: | "Confirmation of resistance is still a nebulous process to many, primarily because published articles on herbicide-resistant weeds describe different protocols for testing resistance. There are also varying degrees of uncertainty about discriminating between tolerant and resistant weed populations. The Weed Science Society of America (WSSA) adopts the following definition of these terminologies. Tolerance is the natural ability of a species to survive herbicide application that severely inhibits another species, without prior exposure to the herbicide. Resistance is the heritable ability of a species to survive herbicide application that normally controls the same species in the past. We also need to recognize that because of the genetic diversity of weeds, there is a difference in natural level of tolerance to a herbicide within a species. This should not be construed as resistance. This paper discusses protocols used at the University of Arkansas for confirmation of herbicide resistance of barnyardgrass (Echinochloa crus-galli), common cocklebur (Xanthium strumarium), Palmer amaranth (Amaranthus palmeri), and ryegrass (Lolium spp.). The methods are discussed in relation to protocols used for other species. Protocols are developed to confirm resistance, levels of resistance, and cross-resistance of samples from farmers' fields that are suspected to be resistant. Protocols vary according to species and herbicides involved; however, there are general principles that apply to any situation. First, is proper seed collection. If possible, collect seed from at least 20 individual plants from one suspected resistant population. Part of the seed can be bulked for confirmation of resistance and the rest stored individually for information on homogeneity of the population. Second, is the use of appropriate susceptible standard. For weeds like ryegrass, which consist of several species, it is critical to use a susceptible standard that is of the same species as the suspected resistant sample. If possible, it is best to use a known susceptible sample from the same county or locality. Different ecotypes of the same species may have different levels of tolerance to the herbicide used. Third, is the use of historical data on herbicide use. This usually resolves the question of whether the population is just tolerant or has become resistant. Fourth, is the establishment of a herbicide response curve in a replicated trial. This allows for proper statistical comparison of various samples, gives information on the level of resistance, and provides baseline information on rates to use for quick confirmation of resistance for future samples. Fifth, is check for cross resistance. This need to be done on more than one resistant samples because cross- and multiple resistance patterns may differ between populations. Petri dish bioassays had been reported to effectively distinguish between resistant and susceptible samples of some species. This method is quick and cheap; however this technique produced misleading results for confirmation of diclofop-resistant ryegrass. Use of methods other than whole-plant assay needs to be carefully evaluated before being adopted as a regular protocol for resistance confirmation." |
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| Language: | English |
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| References: | 0 |
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| Note: | This item is an abstract only! |
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| ASA/CSSA/SSSA Citation (Crop Science-Like - may be incomplete):
Burgos, N. R., and R. E. Talbert. 2002. How do we test for herbicide resistance?. South. Weed Sci. Soc. Proc. 55:p. 130-131. |
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MSU catalog number: SB 611 .S6 v.54 |
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