Topramezone Active Herbicide: Post-Emergent Herbicide for Maize Crops

Topramezone active herbicide is a highly flexible, post-emergent herbicide for all types of maize growers. It helps protect yield potential by providing excellent control of tough broadleaf weeds and grasses. Topramezone is a pyrazolone, a unique subclass of the hydroxyphenylpyruvate dioxygenase (HPPD) inhibiting herbicides. It offers highly effective, selective and consistent control of key broadleaf weeds and grasses, including those that have developed resistance to glyphosate, triazines, PPO- and ALS-inhibitors. It is available as Clio® herbicide and Armezon® herbicide.

Key Features and Benefits of Topramezone


  • Unique site of action provides broad-spectrum control of annual grasses and broadleaf weeds
  • Safe for use on all field and specialty maize (corn) regardless of trait, including pop, sweet and seed varieties that are sensitive to other herbicides
  • Excellent compatibility with other types of herbicides used in agriculture, either as a tank mixture or as part of a weed management program
  • Combination with PSII inhibitors, like triazines, can achieve significant weed control synergy


  • Offers an additional tool for weed resistance management and crop protection
  • Wide postemergence application window to give growers application flexibility
  • Low active ingredient use rates provide convenient handling and low environmental exposure

Mode of Action

When Topramezone is used as a post-emergent herbicide, susceptible weeds take up the herbicide through the treated foliage and it moves systemically throughout the plant. Once in the weed, topramezone is a potent inhibitor of the HPPD enzyme, which results in oxidative degradation of chlorophyl. This leads to pronounced whitening or “bleaching” of sensitive weeds. These bleaching effects will be visible on new growth within five days of treatment. Ultimately, growth is inhibited, tissue becomes necrotic and weeds usually die within 7-14 days after herbicide application. Because maize rapidly metabolizes topramezone to non-active substances, it has excellent selectivity in maize, including field (grain, silage and seed), sweet and pop varieties regardless of trait.

Topramezone at-a-glance

Key Growth Areas

  • Canadian canola
  • New premixes to be registered in Mexico
  • India