Group 15 (VLCFA inhibitors) Resistance

HRAC has created a Group 15 Working Group to discuss and agree on common advices regarding the combination or sequence of actives ingredients belonging to that group. In September 2021, the Working Group published a recommendation letter that can be consulted here.

In January 2020, HRAC updated the mode of action classification scheme, adding new mode of action classes and reviewing the correct positioning of each active ingredient. For legacy HRAC group N it turned out that most of its active ingredients needed to be moved into HRAC group 15 (legacy group K3) and class N was deleted.

Combinations or sequences of products containing active ingredients from different HRAC groups are part of resistance management recommendations. In line with this advice, it is common practice for farmers to tank-mix or sequence products of the former HRAC groups N and K3 to control grasses like Alopecurus spp. or Lolium spp.

Based on this experience and the fact that HRAC group 15 (K3) covers a multi-enzyme mode of action with a complex pattern of substrate specificity, combinations or sequences of products containing active ingredients from the former HRAC Groups N and K3 (new Group 15) are still supported by HRAC.