Weed scientists generally have done an excellent job of documenting herbicideresistant weeds. Over 400 unique cases of herbicide resistance, involving over 200 weed species in 65 countries, have been reported (Heap 2014). Oftentimes, evolved resistance in weeds is due to a mutation in a gene encoding the herbicide target site, and weed scientists also have done a good job of identifying these m...

Gene flow exposed by genetically engineered crops Gene flow is the transfer of genes between populations of the same or related species. The exchange between crop cultivars of genes selected by traditional breeding that confer characteristics such as shorter stems, higher yield, or increased seed quality will attract little attention. In the same way, crop-weed hybrids having acquired traits su...

A year after the introduction of the first commercial transgenic crop (Flavr SavrTM tomato with a longer shelf life) in 1994, transgenic, herbicide-resistant crops (HRCs) were introduced (Table 3.1) with the introduction of bromoxynil(3,5dibromo-4-hydroxybenzonitrile) resistant cotton and glufosinate[2-amino-4(hydroxymethylphosphinyl)butanoic acid] resistant canola. Bromoxynil resistance had li...

Evolutionary physiology merges the disciplines of evolution and physiology, and it is a research approach that has not received much attention for studying the development of herbicide resistance. This paper makes a case for using evolutionary physiology more frequently when studying herbicide resistance, and illustrates this using three areas where more work would be useful: (i) the interactio...

BACKGROUND Herbicide mixtures are commonly proposed to delay the selection of herbicide resistance in susceptible populations (called the SM strategy). However, in practice, herbicide mixtures are often used when resistance to one of the two active ingredients has already been detected in the targeted population (called the RM strategy). It is doubtful whether such a practice can select against...