Woody Weed Herbicides

Liquid herbicides for woody weeds

Liquid herbicides are typically applied through foliar spraying, basal barking, or cut-stump treatments. These herbicides are available in both selective formulations for application without off-target damage, and non-selective formulations for total weed control.

Common liquid herbicides for woody weeds include: 

• Triclopyr: A selective herbicide that works by disrupting growth processes and killing the target plant. Triclopyr is effective against species like lantana, blackberries, and wattle, and is commonly used in combination with picloram or aminopyralid. 

• Picloram: A powerful selective herbicide often combined with other products to enhance effectiveness. Picloram provides residual control in the soil, preventing regrowth.

• Aminopyralid: Another selective herbicide that’s most effective when used in conjunction with actives like triclopyr and picloram. Like triclopyr, it works by disrupting plant growth processes. 

• Glyphosate: A broad-spectrum herbicide that kills most plant species and is often used in cut-stump applications. 

• Fluroxypyr: A selective herbicide that works by disturbing plant growth hormones, leading to abnormal growth and eventually, death. 
• Hexazinone: A long-lasting soil-active herbicide available in both liquid and granular formulations that controls deep-rooted woody weeds. It works by inhibiting photosynthesis, starving the plant of energy until it dies. 

Depending on the size of the infestation, liquid herbicides can be applied using high-volume sprayers, low-volume backpack sprayers, or aerially. 

Granular herbicides to control woody weeds

Granular herbicides are ideal for areas where liquid application is impractical like steep terrain or locations with sensitive non-target vegetation. These products are applied directly to the soil and rely on moisture to be activated. They’re effective against species with extensive root systems that are hard to control with foliar sprays. 

In addition to hexazinone and glyphosate, popular granular herbicides include:

• Tebuthiuron: A soil-applied residual herbicide used to control species like mesquite and prickly acacia by targeting the root system. Tebuthiuron works by inhibiting photosynthesis.
• Metsulfuron-methyl: A systemic, selective herbicide used to control woody plants and broadleaf weeds in pastures and non-crop areas. It works by inhibiting the acetolactate synthase (ALS) enzyme, leading to plant death. It’s extremely effective when paired with liquid herbicides.

Compared to liquid formulations, granular herbicides offer longer control, but they require careful application to avoid unintended environmental impact.

What are gel herbicides for controlling woody weeds? 

Gel-based herbicides, which typically contain picloram and aminopyralid, are designed for precision application on cut stumps or stems, reducing the risk of drift and off-target effectives and ensuring rapid uptake and an effective kill. They’re ideal for targeted applications in sensitive areas and help reduce herbicide wastage.

Additional products to improve herbicide efficacy against woody weeds

These products can be used to enhance the effectiveness and efficiency of herbicides: 

• Marker dyes: Added to spray solutions to visibly indicate treated areas. They reduce the risk of missed spots or overapplication, making them especially useful in large-scale operations and when spot spraying.

• Wetting agents and penetrants: Designed to improve herbicide uptake by enhancing contact with plant surfaces. These products break down the waxy cuticle of woody weeds for better absorption of your chosen herbicide.