Agronomy Journal (2013) 105, 854-862

Erik A. Lehnhoff, Barbara K. Keith, William E. Dyer, Robert K. Peterson and Fabian Menalled (2013)
Multiple herbicide resistance in wild oat and impacts on physiology, germinability, and seed production
Agronomy Journal 105 (3), 854-862
Abstract: The evolution of weed biotypes resistant to multiple herbicide modes of action, here termed multiple herbicide resistance, is a growing problem around the world. We investigated two multiple herbicide resistant (MHR) wild oat (Avena fatua L.) populations from Montana and hypothesized that they would exhibit fitness costs compared with two herbicide-susceptible (HS) populations. Dose-response tests showed that the MHR populations were resistant to difenzoquat (a membrane disruptor), imazamethabenz (an acetolactate synthase [ALS] inhibitor), flucarbazone (an ALS inhibitor), and tralkoxydim (an acetyl-CoA carboxylase inhibitor). In greenhouse studies, we assessed differences between MHR and HS populations in seed germination, photosynthetic parameters, plant growth, and reproduction. Seeds of one HS population germinated more at cold temperature (4.9°C) and less at high temperature (29.6°C) compared with the other populations. Plants of this HS population also had lower stomatal conductance (23%), intercellular CO₂ concentration (7.5%), and transpiration (15.3%) than the other populations, but there were no differences in photosynthetic rates between any populations. Also, there were no differences in relative growth rate among all HS and MHR populations. The MHR populations initiated seed production several days sooner than the HS populations; however, HS populations produced 67% more tillers, and one HS population ultimately produced 43% more seeds than the MHR populations, indicating a potential fitness cost of resistance. With the exception of seed production differences, our results do not indicate a consistent fitness cost. More research is needed in field settings and with resource competition to further evaluate fitness costs in MHR populations.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Erik A. Lehnhoff, Robert K.D. Peterson, William E. Dyer, Fabián D. Menalled

Research topic(s) for pests/diseases/weeds:
pesticide resistance of pest

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Avena fatua (weed)		U.S.A. (NW)