Identification of glyphosate resistance in Salsola tragus in north‐eastern Oregon

BACKGROUND Farmers in the low‐rainfall region of eastern Oregon rely on repeated applications of non‐selective herbicides, predominately glyphosate, to control Salsola tragus in no‐till fallow systems. Reports of poor glyphosate effectiveness have increased in recent years. Reduced efficacy is often...

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Bibliographic Details
Published in:Pest management science 2018-05, Vol.74 (5), p.1089-1093
Main Authors: Barroso, Judit, Gourlie, Jennifer A, Lutcher, Larry K, Liu, Mingyang, Mallory‐Smith, Carol A
Format: Article
Language:English
Subjects:
Aridity
Cropping systems
Dust control
Fallow land
Glycine - analogs & derivatives
Glycine - pharmacology
Glyphosate
glyphosate‐resistant
Herbicide Resistance
Herbicides
Herbicides - pharmacology
Oregon
Plant resistance
Plants (botany)
Populations
Rainfall
Russian thistle
Salsola - drug effects
Salsola - physiology
Salsola kali
Salsola tragus
Sustainability
System effectiveness
tumbleweed
Water stress
Weed control
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Summary:BACKGROUND Farmers in the low‐rainfall region of eastern Oregon rely on repeated applications of non‐selective herbicides, predominately glyphosate, to control Salsola tragus in no‐till fallow systems. Reports of poor glyphosate effectiveness have increased in recent years. Reduced efficacy is often attributed to dust, water stress, or generally poor growing conditions during application. Inadequate control also may be the result of the evolution of glyphosate resistance. Therefore, studies were undertaken to determine if glyphosate‐resistant S. tragus populations occur in Oregon. RESULTS Results from dose–response studies confirmed glyphosate resistance in three of 10 Oregon Salsola tragus populations. The ratio I50R/I50S from dose–response curves was, on average, 3.1 for the relative dry biomass per plant and 3.2 for the % of surviving plants per pot in these three populations. Plant mortality at recommended glyphosate doses for the resistant populations was less than 30% 3 weeks after treatment. CONCLUSIONS Glyphosate resistance in S. tragus highlights the imperative need to diversify weed control strategies to preserve the longevity and sustainability of herbicides in semi‐arid cropping systems of the Pacific Northwest. © 2017 Society of Chemical Industry Results from dose–response studies confirmed glyphosate resistance in three of ten Oregon S. tragus populations. The ratio I50R/I50S was, on average, 3.1 for the relative dry biomass per plant.
ISSN:1526-498X
1526-4998
DOI:10.1002/ps.4525