Hexazinone: A Broad-Spectrum Triazine Herbicide

Technical Introduction

Hexazinone (IUPAC: 3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1H,3H)-dione) is a broad-spectrum, systemic herbicide belonging to the triazine chemical family.

It works by inhibiting photosystem II (PSII) in the photosynthetic pathway, preventing electron transport and energy production. As a result, treated weeds undergo chlorosis (yellowing), necrosis, and ultimately die.

• Mode of Action: Photosystem II inhibitor (HRAC Group C1 / WSSA Group 5).

• Systemicity: Absorbed by roots and foliage, translocated through xylem.

• Application Timing: Pre- and post-emergence.

Applications

• Forestry & Non-Crop Use:

  • Used extensively in pine plantations for selective grass and broadleaf control.

  • Controls competing vegetation around young conifers.

• Agriculture:

  • Alfalfa (for weed control without harming the crop).

  • Sugarcane, pineapple, blueberry, and coffee.

• Non-Agricultural Areas:

  • Industrial sites, railways, rights-of-way, and rangelands.

• Weeds Controlled:

  • Annual and perennial grasses (Poa annua, Digitaria spp.).

  • Broadleaf weeds (Amaranthus spp., Chenopodium spp.).

  • Woody brush and vines (Rubus spp., Acer spp., Populus spp.).

Advantages

• Broad-Spectrum Control: Effective against grasses, broadleaf weeds, and woody brush.

• Flexible Application: Works as both pre- and post-emergence herbicide.

• Residual Activity: Provides extended weed suppression through soil activity.

• Forestry Selectivity: Especially effective in conifer plantations without harming young trees.

• Versatility: Useful in both agricultural crops and non-crop areas.

Specifications (Typical Parameters)

FAQ

Q1: What is Hexazinone mainly used for?
A: It is widely used in forestry (pine plantations), alfalfa, sugarcane, pineapple, and non-crop areas for long-term weed control.

Q2: Is Hexazinone selective?
A: Yes, it is selective in certain crops (e.g., alfalfa, pine, blueberry), but non-selective in many others.

Q3: How long does Hexazinone last in soil?
A: It has a moderate persistence, lasting weeks to months, depending on soil type, rainfall, and temperature.

Q4: How does Hexazinone compare with Atrazine?
A: Both are triazine herbicides, but Hexazinone is more soluble and more effective on woody plants and perennial weeds, while Atrazine is more commonly used in row crops (maize, sorghum).

Q5: What is the application method?
A: Typically applied via ground or aerial spray, either pre- or post-emergence. In forestry, often applied around young trees to reduce weed competition.

Q6: Is resistance an issue with Hexazinone?
A: Resistance is less common than with atrazine, but cases of PSII-resistant Amaranthus and Chenopodium species have been reported.