Herbicide Safeners: an overview

Abstract

A significant number of herbicides used in cereals, corn and rice owe their strong efficacy aligned with crop selectivity to safeners. The first commercial safener was 1,8-naphthalic anhydride used as a seed treatment in corn. Since then approximately 20 Safeners have been commercialized in monocot crops, although several were superseded. According to independent market research, in 2011 approximately 30% of herbicide use value from all companies in corn and cereals came from products containing safeners. In rice the percentage was 6%. Almost all safeners work by inducing the expression of genes which code for enzymes involved in herbicide detoxification. Thereby, herbicides are degraded rapidly enough to ensure a damaging concentration is not reached. This gene induction may occur in just one crop or several. For commercial success no significant induction of herbicide degradation should occur in the weeds. The actual molecular target(s) of safeners is/are not known and therefore the reasons for species specificity are unclear. Bayer CropScience has a strong track record of safener discovery and has developed product portfolios based on its safeners mefenpyr-diethyl, isoxadifen-ethyl and cyprosulfamide. Atlantis® WG and Laudis® OD are important Bayer CropScience-products in Germany. These contain mefenpyr-diethyl to safen wheat and isoxadifen-ethyl to safen corn, respectively. The safeners provide an enabling technology which together with strong herbicide molecules has helped farmers to optimize their crop productivity through improved weed management.

Keywords

• crop safety
• herbicide detoxification
• metabolism
• phytotoxicity
• safener
• selectivity