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. 2018 Feb 15;74(10):2265–2276. doi: 10.1002/ps.4823

Figure 6.

PS-4823-FIG-0006-c

Number of weed species with reported resistance by year after introduction of ALS inhibitors (HRAC group B), ACCase inhibitors (HRAC group A), glyphosate (HRAC group G), and synthetic auxin* (HRAC group O) herbicides through 20171 and ranked by the relative rate of weed resistance development. Rate of weed resistance development is estimated by dividing number of weed species reported resistant by the number of years since the mode of action was introduced. For example, 159 weed species have been confirmed to be resistant to ALS inhibitor herbicides over a span of 38 years, which is about 4.2 species per year. *The resistance development time line for the synthetic auxin mode of action only includes broadleaf weeds and not the 5 grass species resistant to quinclorac and 1 grass‐like species resistant to 2,4‐D listed on http://weedscience.org.