Comments fiutzi has made

  • Availability of Science papers

    PDFs of the two Science papers by Searchinger et al. and Fargione et al. are among the links at the bottom of this page: http://www.gmfus.org/press/article.cfm?id=132On ILSR, spinning like a top posted 1 year, 9 months ago 7 Responses

  • Glyphosate rates and weed resistance

    Herbicide resistance has so far generally been considered monogenic, as wiscidea suggested.  When only one gene controls resistance, it makes sense that herbicide rate should not affect the likelihood of resistance eventually developing.  (Although it can influence the amount of time it takes for resistance to evolve).

    Evidence is growing, though, for polygenic glyphosate resistance in at least two weed species -- tall waterhemp in the US (1) and rigid ryegrass in Australia (2).  Assumptions about single-gene control and additivity are steadily being overturned in plant genetics, so it wouldn't be surprising if we discover more such situations.

    But separate from literal physiological resistance, it's pretty clear that weed communities are "evolving" greater "resistance" to glyphosate when a low rate of that herbicide is the primary weed control tactic (3).  The weed species that are naturally less vulnerable are the ones that survive, reproduce, and increase in relative abundance.  

    What I hear from farmers and from my agronomy colleagues supports reports that glyphosate rates are increasing in the US.  The management-induced ecological shift toward tougher weeds is definitely the biggest reason for that.

    (1) http://dx.doi.org/10.1002/ps.1074
    (2) http://dx.doi.org/10.1007/s00122-005-1947-2
    (3) http://dx.doi.org/10.1002/ps.1539On While global GMO acreage surges, herbicide-resistent weeds thrive posted 1 year, 9 months ago 29 Responses