The 'Group' letters/numbers that you see throughout this web site refer to the classification of herbicides by their site of action. To see a full list of herbicides and HRAC herbicide classifications click here.
QUIK STATS (last updated May 07, 2017 )
NOTES ABOUT THIS BIOTYPE
April 2017 Update
This is the first report on resistance in L. perenne in Denmark. Three cases were identified in the herbicide resistance survey on untreated plots in agricultural fields all over Denmark. Overall L. perenne was resistant in 19% of the fields (3 out of 16 samples, to be presented in Denver in May). The samples were tested in pot experiments including a susceptible reference population. Two samples were resistant to iodosulfuron and one to clodinafop. The resistance factors were <5 indicating enhanced metabolism as the most likely mechanism of resistance.
CONTRIBUTING WEED SCIENTISTS
Perennial ryegrass (Lolium perenne) has developed resistance to glyphosate within New Zealand vineyards following many years of herbicide application. The objectives of this work were to confirm resistance within two populations obtained from affected vineyards, and to determine the mechanism of resistance to glyphosate.
Population O was confirmed to have a 25‐fold resistance to glyphosate, whereas population J had a sevenfold resistance. Results of genotyping assays demonstrated a single nucleotide substitution at codon 106 of 5‐enolpyruvylshikimate‐3‐phosphate synthase in population O but not population J. Glyphosate‐resistant and glyphosate‐susceptible populations did not differ in glyphosate absorption. However, in both resistant populations, much more of the absorbed 14C‐glyphosate remained in the treated leaf than occurred in the susceptible population. Significantly more glyphosate was found in the pseudostem region of susceptible plants compared with resistant plants.
Both target‐site and non‐target‐site mechanisms of glyphosate resistance were found in the perennial ryegrass population with 25‐fold resistance, whereas only the non‐target‐site mechanism of resistance was found in the population with sevenfold resistance. This is the first study of the mechanism of glyphosate resistance in perennial ryegrass.